An example of a web server written with Node which responds with 'Hello World':
var http = require('http');
http.createServer(function (request, response) {
response.writeHead(200, {'Content-Type': 'text/plain'});
response.end('Hello World\n');
}).listen(8124);
console.log('Server running at http://127.0.0.1:8124/');To run the server, put the code into a file called example.js and execute
it with the node program
> node example.js
Server running at http://127.0.0.1:8124/All of the examples in the documentation can be run similarly.
These object are available in all modules. Some of these objects aren't actually in the global scope but in the module scope - this will be noted.
The global namespace object.
In browsers, the top-level scope is the global scope. That means that in
browsers if you're in the global scope var something will define a global
variable. In Node this is different. The top-level scope is not the global
scope; var something inside a Node module will be local to that module.
The process object. See the process object section.
Used to print to stdout and stderr. See the stdio section.
To require modules. See the Modules section.
require isn't actually a global but rather local to each module.
Use the internal require() machinery to look up the location of a module,
but rather than loading the module, just return the resolved filename.
Modules are cached in this object when they are required. By deleting a key
value from this object, the next require will reload the module.
An array of search paths for require(). This array can be modified to add
custom paths.
Example: add a new path to the beginning of the search list
require.paths.unshift('/usr/local/node');The filename of the script being executed. This is the absolute path, and not necessarily the same filename passed in as a command line argument.
Example: running node example.js from /Users/mjr
console.log(__filename);
// /Users/mjr/example.js__filename isn't actually a global but rather local to each module.
The dirname of the script being executed.
Example: running node example.js from /Users/mjr
console.log(__dirname);
// /Users/mjr__dirname isn't actually a global but rather local to each module.
A reference to the current module. In particular
module.exports is the same as the exports object. See src/node.js
for more information.
module isn't actually a global but rather local to each module.
An object which is shared between all instances of the current module and
made accessible through require().
exports is the same as the module.exports object. See src/node.js
for more information.
exports isn't actually a global but rather local to each module.
The timer functions are global variables. See the timers section.
Browser-like object for printing to stdout and stderr.
Prints to stdout with newline. This function can take multiple arguments in a
printf()-like way. Example:
console.log('count: %d', count);If formating elements are not found in the first string then util.inspect
is used on each argument.
Same as console.log.
Same as console.log but prints to stderr.
Uses util.inspect on obj and prints resulting string to stderr.
Mark a time.
Finish timer, record output. Example
console.time('100-elements');
for (var i = 0; i < 100; i++) {
;
}
console.timeEnd('100-elements');Print a stack trace to stderr of the current position.
Same as assert.ok().
To schedule execution of callback after delay milliseconds. Returns a
timeoutId for possible use with clearTimeout(). Optionally, you can
also pass arguments to the callback.
Prevents a timeout from triggering.
To schedule the repeated execution of callback every delay milliseconds.
Returns a intervalId for possible use with clearInterval(). Optionally,
you can also pass arguments to the callback.
Stops a interval from triggering.
Node has a simple module loading system. In Node, files and modules are in
one-to-one correspondence. As an example, foo.js loads the module
circle.js in the same directory.
The contents of foo.js:
var circle = require('./circle.js');
console.log( 'The area of a circle of radius 4 is '
+ circle.area(4));The contents of circle.js:
var PI = Math.PI;
exports.area = function (r) {
return PI * r * r;
};
exports.circumference = function (r) {
return 2 * PI * r;
};The module circle.js has exported the functions area() and
circumference(). To export an object, add to the special exports
object.
Variables
local to the module will be private. In this example the variable PI is
private to circle.js.
Node has several modules compiled into the binary. These modules are described in greater detail elsewhere in this documentation.
The core modules are defined in node's source in the lib/ folder.
Core modules are always preferentially loaded if their identifier is
passed to require(). For instance, require('http') will always
return the built in HTTP module, even if there is a file by that name.
If the exact filename is not found, then node will attempt to load the
required filename with the added extension of .js, and then .node.
.js files are interpreted as JavaScript text files, and .node files
are interpreted as compiled addon modules loaded with dlopen.
A module prefixed with '/' is an absolute path to the file. For
example, require('/home/marco/foo.js') will load the file at
/home/marco/foo.js.
A module prefixed with './' is relative to the file calling require().
That is, circle.js must be in the same directory as foo.js for
require('./circle') to find it.
Without a leading '/' or './' to indicate a file, the module is either a
"core module" or is loaded from a node_modules folder.
If the module identifier passed to require() is not a native module,
and does not begin with '/', '../', or './', then node starts at the
parent directory of the current module, and adds /node_modules, and
attempts to load the module from that location.
If it is not found there, then it moves to the parent directory, and so on, until the root of the tree is reached.
For example, if the file at '/home/ry/projects/foo.js' called
require('bar.js'), then node would look in the following locations, in
this order:
/home/ry/projects/node_modules/bar.js/home/ry/node_modules/bar.js/home/node_modules/bar.js/node_modules/bar.jsThis allows programs to localize their dependencies, so that they do not clash.
It is convenient to organize programs and libraries into self-contained
directories, and then provide a single entry point to that library.
There are three ways in which a folder may be passed to require() as
an argument.
The first is to create a package.json file in the root of the folder,
which specifies a main module. An example package.json file might
look like this:
{ "name" : "some-library",
"main" : "./lib/some-library.js" }If this was in a folder at ./some-library, then
require('./some-library') would attempt to load
./some-library/lib/some-library.js.
This is the extent of Node's awareness of package.json files.
If there is no package.json file present in the directory, then node
will attempt to load an index.js or index.node file out of that
directory. For example, if there was no package.json file in the above
example, then require('./some-library') would attempt to load:
./some-library/index.js./some-library/index.nodeModules are cached after the first time they are loaded. This means
(among other things) that every call to require('foo') will get
exactly the same object returned, if it would resolve to the same file.
Multiple calls to require('foo') may not cause the module code to be
executed multiple times. This is an important feature. With it,
"partially done" objects can be returned, thus allowing transitive
dependencies to be loaded even when they would cause cycles.
If you want to have a module execute code multiple times, then export a function, and call that function.
Modules are cached based on their resolved filename. Since modules may
resolve to a different filename based on the location of the calling
module (loading from node_modules folders), it is not a guarantee
that require('foo') will always return the exact same object, if it
would resolve to different files.
The exports object is created by the Module system. Sometimes this is not
acceptable, many want their module to be an instance of some class. To do this
assign the desired export object to module.exports. For example suppose we
were making a module called a.js
var EventEmitter = require('events').EventEmitter;
module.exports = new EventEmitter();
// Do some work, and after some time emit
// the 'ready' event from the module itself.
setTimeout(function() {
module.exports.emit('ready');
}, 1000);Then in another file we could do
var a = require('./a');
a.on('ready', function() {
console.log('module a is ready');
});Note that assignment to module.exports must be done immediately. It cannot be
done in any callbacks. This does not work:
x.js:
setTimeout(function() {
module.exports = { a: "hello" };
}, 0);y.js:
var x = require('./x');
console.log(x.a);To get the exact filename that will be loaded when require() is called, use
the require.resolve() function.
Putting together all of the above, here is the high-level algorithm in pseudocode of what require.resolve does:
require(X) from module at path Y
1. If X is a core module,
a. return the core module
b. STOP
2. If X begins with './' or '/' or '../'
a. LOAD_AS_FILE(Y + X)
b. LOAD_AS_DIRECTORY(Y + X)
3. LOAD_NODE_MODULES(X, dirname(Y))
4. THROW "not found"
LOAD_AS_FILE(X)
1. If X is a file, load X as JavaScript text. STOP
2. If X.js is a file, load X.js as JavaScript text. STOP
3. If X.node is a file, load X.node as binary addon. STOP
LOAD_AS_DIRECTORY(X)
1. If X/package.json is a file,
a. Parse X/package.json, and look for "main" field.
b. let M = X + (json main field)
c. LOAD_AS_FILE(M)
2. LOAD_AS_FILE(X/index)
LOAD_NODE_MODULES(X, START)
1. let DIRS=NODE_MODULES_PATHS(START)
2. for each DIR in DIRS:
a. LOAD_AS_FILE(DIR/X)
b. LOAD_AS_DIRECTORY(DIR/X)
NODE_MODULES_PATHS(START)
1. let PARTS = path split(START)
2. let ROOT = index of first instance of "node_modules" in PARTS, or 0
3. let I = count of PARTS - 1
4. let DIRS = []
5. while I > ROOT,
a. if PARTS[I] = "node_modules" CONTINUE
c. DIR = path join(PARTS[0 .. I] + "node_modules")
b. DIRS = DIRS + DIR
c. let I = I - 1
6. return DIRSIn node, require.paths is an array of strings that represent paths to
be searched for modules when they are not prefixed with '/', './', or
'../'. For example, if require.paths were set to:
[ '/home/micheil/.node_modules',
'/usr/local/lib/node_modules' ]Then calling require('bar/baz.js') would search the following
locations:
'/home/micheil/.node_modules/bar/baz.js''/usr/local/lib/node_modules/bar/baz.js'The require.paths array can be mutated at run time to alter this
behavior.
It is set initially from the NODE_PATH environment variable, which is
a colon-delimited list of absolute paths. In the previous example,
the NODE_PATH environment variable might have been set to:
/home/micheil/.node_modules:/usr/local/lib/node_modulesLoading from the require.paths locations is only performed if the
module could not be found using the node_modules algorithm above.
Global modules are lower priority than bundled dependencies.
require.paths may disappear in a future release.
While it seemed like a good idea at the time, and enabled a lot of
useful experimentation, in practice a mutable require.paths list is
often a troublesome source of confusion and headaches.
This does not do what one might expect:
require.paths = [ '/usr/lib/node' ];All that does is lose the reference to the actual node module lookup paths, and create a new reference to some other thing that isn't used for anything.
If you do this:
require.paths.push('./lib');then it does not add the full resolved path to where ./lib
is on the filesystem. Instead, it literally adds './lib',
meaning that if you do require('y.js') in /a/b/x.js, then it'll look
in /a/b/lib/y.js. If you then did require('y.js') in
/l/m/n/o/p.js, then it'd look in /l/m/n/o/lib/y.js.
In practice, people have used this as an ad hoc way to bundle dependencies, but this technique is brittle.
There is (by regrettable design), only one require.paths array used by
all modules.
As a result, if one node program comes to rely on this behavior, it may permanently and subtly alter the behavior of all other node programs in the same process. As the application stack grows, we tend to assemble functionality, and those parts interact in ways that are difficult to predict.
When a file is run directly from Node, require.main is set to its
module. That means that you can determine whether a file has been run
directly by testing
require.main === moduleFor a file foo.js, this will be true if run via node foo.js, but
false if run by require('./foo').
Because module provides a filename property (normally equivalent to
__filename), the entry point of the current application can be obtained
by checking require.main.filename.
The semantics of Node's require() function were designed to be general
enough to support a number of sane directory structures. Package manager
programs such as dpkg, rpm, and npm will hopefully find it possible to
build native packages from Node modules without modification.
Below we give a suggested directory structure that could work:
Let's say that we wanted to have the folder at
/usr/lib/node/<some-package>/<some-version> hold the contents of a
specific version of a package.
Packages can depend on one another. In order to install package foo, you
may have to install a specific version of package bar. The bar package
may itself have dependencies, and in some cases, these dependencies may even
collide or form cycles.
Since Node looks up the realpath of any modules it loads (that is,
resolves symlinks), and then looks for their dependencies in the
node_modules folders as described above, this situation is very simple to
resolve with the following architecture:
/usr/lib/node/foo/1.2.3/ - Contents of the foo package, version 1.2.3./usr/lib/node/bar/4.3.2/ - Contents of the bar package that foo
depends on./usr/lib/node/foo/1.2.3/node_modules/bar - Symbolic link to
/usr/lib/node/bar/4.3.2/./usr/lib/node/bar/4.3.2/node_modules/* - Symbolic links to the packages
that bar depends on.Thus, even if a cycle is encountered, or if there are dependency conflicts, every module will be able to get a version of its dependency that it can use.
When the code in the foo package does require('bar'), it will get the
version that is symlinked into /usr/lib/node/foo/1.2.3/node_modules/bar.
Then, when the code in the bar package calls require('quux'), it'll get
the version that is symlinked into
/usr/lib/node/bar/4.3.2/node_modules/quux.
Furthermore, to make the module lookup process even more optimal, rather
than putting packages directly in /usr/lib/node, we could put them in
/usr/lib/node_modules/<name>/<version>. Then node will not bother
looking for missing dependencies in /usr/node_modules or /node_modules.
In order to make modules available to the node REPL, it might be useful to
also add the /usr/lib/node_modules folder to the $NODE_PATH environment
variable. Since the module lookups using node_modules folders are all
relative, and based on the real path of the files making the calls to
require(), the packages themselves can be anywhere.
Addons are dynamically linked shared objects. They can provide glue to C and C++ libraries. The API (at the moment) is rather complex, involving knowledge of several libraries:
V8 JavaScript, a C++ library. Used for interfacing with JavaScript:
creating objects, calling functions, etc. Documented mostly in the
v8.h header file (deps/v8/include/v8.h in the Node source tree).
libev, C event loop library. Anytime one needs to wait for a file
descriptor to become readable, wait for a timer, or wait for a signal to
received one will need to interface with libev. That is, if you perform
any I/O, libev will need to be used. Node uses the EV_DEFAULT event
loop. Documentation can be found here.
libeio, C thread pool library. Used to execute blocking POSIX system
calls asynchronously. Mostly wrappers already exist for such calls, in
src/file.cc so you will probably not need to use it. If you do need it,
look at the header file deps/libeio/eio.h.
Internal Node libraries. Most importantly is the node::ObjectWrap
class which you will likely want to derive from.
Others. Look in deps/ for what else is available.
Node statically compiles all its dependencies into the executable. When compiling your module, you don't need to worry about linking to any of these libraries.
To get started let's make a small Addon which does the following except in C++:
exports.hello = 'world';To get started we create a file hello.cc:
#include <v8.h>
using namespace v8;
extern "C" void
init (Handle<Object> target)
{
HandleScope scope;
target->Set(String::New("hello"), String::New("world"));
}This source code needs to be built into hello.node, the binary Addon. To
do this we create a file called wscript which is python code and looks
like this:
srcdir = '.'
blddir = 'build'
VERSION = '0.0.1'
def set_options(opt):
opt.tool_options('compiler_cxx')
def configure(conf):
conf.check_tool('compiler_cxx')
conf.check_tool('node_addon')
def build(bld):
obj = bld.new_task_gen('cxx', 'shlib', 'node_addon')
obj.target = 'hello'
obj.source = 'hello.cc'Running node-waf configure build will create a file
build/default/hello.node which is our Addon.
node-waf is just WAF, the python-based build system. node-waf is
provided for the ease of users.
All Node addons must export a function called init with this signature:
extern 'C' void init (Handle<Object> target)For the moment, that is all the documentation on addons. Please see https://github.com/ry/node_postgres for a real example.
The process object is a global object and can be accessed from anywhere.
It is an instance of EventEmitter.
function () {}
Emitted when the process is about to exit. This is a good hook to perform constant time checks of the module's state (like for unit tests). The main event loop will no longer be run after the 'exit' callback finishes, so timers may not be scheduled.
Example of listening for exit:
process.on('exit', function () {
process.nextTick(function () {
console.log('This will not run');
});
console.log('About to exit.');
});function (err) { }
Emitted when an exception bubbles all the way back to the event loop. If a listener is added for this exception, the default action (which is to print a stack trace and exit) will not occur.
Example of listening for uncaughtException:
process.on('uncaughtException', function (err) {
console.log('Caught exception: ' + err);
});
setTimeout(function () {
console.log('This will still run.');
}, 500);
// Intentionally cause an exception, but don't catch it.
nonexistentFunc();
console.log('This will not run.');Note that uncaughtException is a very crude mechanism for exception
handling. Using try / catch in your program will give you more control over
your program's flow. Especially for server programs that are designed to
stay running forever, uncaughtException can be a useful safety mechanism.
function () {}
Emitted when the processes receives a signal. See sigaction(2) for a list of standard POSIX signal names such as SIGINT, SIGUSR1, etc.
Example of listening for SIGINT:
// Start reading from stdin so we don't exit.
process.stdin.resume();
process.on('SIGINT', function () {
console.log('Got SIGINT. Press Control-D to exit.');
});An easy way to send the SIGINT signal is with Control-C in most terminal
programs.
A Writable Stream to stdout.
Example: the definition of console.log
console.log = function (d) {
process.stdout.write(d + '\n');
};A writable stream to stderr. Writes on this stream are blocking.
A Readable Stream for stdin. The stdin stream is paused by default, so one
must call process.stdin.resume() to read from it.
Example of opening standard input and listening for both events:
process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function (chunk) {
process.stdout.write('data: ' + chunk);
});
process.stdin.on('end', function () {
process.stdout.write('end');
});An array containing the command line arguments. The first element will be 'node', the second element will be the name of the JavaScript file. The next elements will be any additional command line arguments.
// print process.argv
process.argv.forEach(function (val, index, array) {
console.log(index + ': ' + val);
});This will generate:
$ node process-2.js one two=three four
0: node
1: /Users/mjr/work/node/process-2.js
2: one
3: two=three
4: fourThis is the absolute pathname of the executable that started the process.
Example:
/usr/local/bin/nodeChanges the current working directory of the process or throws an exception if that fails.
console.log('Starting directory: ' + process.cwd());
try {
process.chdir('/tmp');
console.log('New directory: ' + process.cwd());
}
catch (err) {
console.log('chdir: ' + err);
}Returns the current working directory of the process.
console.log('Current directory: ' + process.cwd());An object containing the user environment. See environ(7).
Ends the process with the specified code. If omitted, exit uses the
'success' code 0.
To exit with a 'failure' code:
process.exit(1);The shell that executed node should see the exit code as 1.
Gets the group identity of the process. (See getgid(2).) This is the numerical group id, not the group name.
console.log('Current gid: ' + process.getgid());Sets the group identity of the process. (See setgid(2).) This accepts either a numerical ID or a groupname string. If a groupname is specified, this method blocks while resolving it to a numerical ID.
console.log('Current gid: ' + process.getgid());
try {
process.setgid(501);
console.log('New gid: ' + process.getgid());
}
catch (err) {
console.log('Failed to set gid: ' + err);
}Gets the user identity of the process. (See getuid(2).) This is the numerical userid, not the username.
console.log('Current uid: ' + process.getuid());Sets the user identity of the process. (See setuid(2).) This accepts either a numerical ID or a username string. If a username is specified, this method blocks while resolving it to a numerical ID.
console.log('Current uid: ' + process.getuid());
try {
process.setuid(501);
console.log('New uid: ' + process.getuid());
}
catch (err) {
console.log('Failed to set uid: ' + err);
}A compiled-in property that exposes NODE_VERSION.
console.log('Version: ' + process.version);A compiled-in property that exposes NODE_PREFIX.
console.log('Prefix: ' + process.installPrefix);Send a signal to a process. pid is the process id and signal is the
string describing the signal to send. Signal names are strings like
'SIGINT' or 'SIGUSR1'. If omitted, the signal will be 'SIGTERM'.
See kill(2) for more information.
Note that just because the name of this function is process.kill, it is
really just a signal sender, like the kill system call. The signal sent
may do something other than kill the target process.
Example of sending a signal to yourself:
process.on('SIGHUP', function () {
console.log('Got SIGHUP signal.');
});
setTimeout(function () {
console.log('Exiting.');
process.exit(0);
}, 100);
process.kill(process.pid, 'SIGHUP');The PID of the process.
console.log('This process is pid ' + process.pid);Getter/setter to set what is displayed in 'ps'.
What platform you're running on. 'linux2', 'darwin', etc.
console.log('This platform is ' + process.platform);Returns an object describing the memory usage of the Node process.
var util = require('util');
console.log(util.inspect(process.memoryUsage()));This will generate:
{ rss: 4935680,
vsize: 41893888,
heapTotal: 1826816,
heapUsed: 650472 }heapTotal and heapUsed refer to V8's memory usage.
On the next loop around the event loop call this callback.
This is not a simple alias to setTimeout(fn, 0), it's much more
efficient.
process.nextTick(function () {
console.log('nextTick callback');
});Sets or reads the process's file mode creation mask. Child processes inherit
the mask from the parent process. Returns the old mask if mask argument is
given, otherwise returns the current mask.
var oldmask, newmask = 0644;
oldmask = process.umask(newmask);
console.log('Changed umask from: ' + oldmask.toString(8) +
' to ' + newmask.toString(8));These functions are in the module 'util'. Use require('util') to access
them.
A synchronous output function. Will block the process and
output string immediately to stderr.
require('util').debug('message on stderr');Output with timestamp on stdout.
require('util').log('Timestamped message.');Return a string representation of object, which is useful for debugging.
If showHidden is true, then the object's non-enumerable properties will be
shown too.
If depth is provided, it tells inspect how many times to recurse while
formatting the object. This is useful for inspecting large complicated objects.
The default is to only recurse twice. To make it recurse indefinitely, pass
in null for depth.
Example of inspecting all properties of the util object:
var util = require('util');
console.log(util.inspect(util, true, null));Experimental
Read the data from readableStream and send it to the writableStream.
When writableStream.write(data) returns false readableStream will be
paused until the drain event occurs on the writableStream. callback gets
an error as its only argument and is called when writableStream is closed or
when an error occurs.
Inherit the prototype methods from one
constructor
into another. The prototype of constructor will be set to a new
object created from superConstructor.
As an additional convenience, superConstructor will be accessible
through the constructor.super_ property.
var util = require("util");
var events = require("events");
function MyStream() {
events.EventEmitter.call(this);
}
util.inherits(MyStream, events.EventEmitter);
MyStream.prototype.write = function(data) {
this.emit("data", data);
}
var stream = new MyStream();
console.log(stream instanceof events.EventEmitter); // true
console.log(MyStream.super_ === events.EventEmitter); // true
stream.on("data", function(data) {
console.log('Received data: "' + data + '"');
})
stream.write("It works!"); // Received data: "It works!"Many objects in Node emit events: a net.Server emits an event each time
a peer connects to it, a fs.readStream emits an event when the file is
opened. All objects which emit events are instances of events.EventEmitter.
You can access this module by doing: require("events");
Typically, event names are represented by a camel-cased string, however, there aren't any strict restrictions on that, as any string will be accepted.
Functions can then be attached to objects, to be executed when an event is emitted. These functions are called listeners.
To access the EventEmitter class, require('events').EventEmitter.
When an EventEmitter instance experiences an error, the typical action is
to emit an 'error' event. Error events are treated as a special case in node.
If there is no listener for it, then the default action is to print a stack
trace and exit the program.
All EventEmitters emit the event 'newListener' when new listeners are
added.
Adds a listener to the end of the listeners array for the specified event.
server.on('connection', function (stream) {
console.log('someone connected!');
});Adds a one time listener for the event. The listener is invoked only the first time the event is fired, after which it is removed.
server.once('connection', function (stream) {
console.log('Ah, we have our first user!');
});Remove a listener from the listener array for the specified event. Caution: changes array indices in the listener array behind the listener.
var callback = function(stream) {
console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);Removes all listeners from the listener array for the specified event.
By default EventEmitters will print a warning if more than 10 listeners are added to it. This is a useful default which helps finding memory leaks. Obviously not all Emitters should be limited to 10. This function allows that to be increased. Set to zero for unlimited.
Returns an array of listeners for the specified event. This array can be manipulated, e.g. to remove listeners.
server.on('connection', function (stream) {
console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')); // [ [Function] ]Execute each of the listeners in order with the supplied arguments.
function (event, listener) { }
This event is emitted any time someone adds a new listener.
Pure Javascript is Unicode friendly but not nice to binary data. When dealing with TCP streams or the file system, it's necessary to handle octet streams. Node has several strategies for manipulating, creating, and consuming octet streams.
Raw data is stored in instances of the Buffer class. A Buffer is similar
to an array of integers but corresponds to a raw memory allocation outside
the V8 heap. A Buffer cannot be resized.
The Buffer object is global.
Converting between Buffers and JavaScript string objects requires an explicit encoding method. Here are the different string encodings;
'ascii' - for 7 bit ASCII data only. This encoding method is very fast, and will
strip the high bit if set.
Note that this encoding converts a null character ('\0' or '\u0000') into
0x20 (character code of a space). If you want to convert a null character
into 0x00, you should use 'utf8'.
'utf8' - Multi byte encoded Unicode characters. Many web pages and other document formats use UTF-8.
'ucs2' - 2-bytes, little endian encoded Unicode characters. It can encode
only BMP(Basic Multilingual Plane, U+0000 - U+FFFF).
'base64' - Base64 string encoding.
'binary' - A way of encoding raw binary data into strings by using only
the first 8 bits of each character. This encoding method is deprecated and
should be avoided in favor of Buffer objects where possible. This encoding
will be removed in future versions of Node.
Allocates a new buffer of size octets.
Allocates a new buffer using an array of octets.
Allocates a new buffer containing the given str.
Writes string to the buffer at offset using the given encoding. Returns
number of octets written. If buffer did not contain enough space to fit
the entire string, it will write a partial amount of the string.
The method will not write partial characters.
Example: write a utf8 string into a buffer, then print it
buf = new Buffer(256);
len = buf.write('\u00bd + \u00bc = \u00be', 0);
console.log(len + " bytes: " + buf.toString('utf8', 0, len));The number of characters written (which may be different than the number of
bytes written) is set in Buffer._charsWritten and will be overwritten the
next time buf.write() is called.
Decodes and returns a string from buffer data encoded with encoding
beginning at start and ending at end.
See buffer.write() example, above.
Get and set the octet at index. The values refer to individual bytes,
so the legal range is between 0x00 and 0xFF hex or 0 and 255.
Example: copy an ASCII string into a buffer, one byte at a time:
str = "node.js";
buf = new Buffer(str.length);
for (var i = 0; i < str.length ; i++) {
buf[i] = str.charCodeAt(i);
}
console.log(buf);
// node.jsTests if obj is a Buffer.
Gives the actual byte length of a string. This is not the same as
String.prototype.length since that returns the number of characters in a
string.
Example:
str = '\u00bd + \u00bc = \u00be';
console.log(str + ": " + str.length + " characters, " +
Buffer.byteLength(str, 'utf8') + " bytes");
// ½ + ¼ = ¾: 9 characters, 12 bytesThe size of the buffer in bytes. Note that this is not necessarily the size
of the contents. length refers to the amount of memory allocated for the
buffer object. It does not change when the contents of the buffer are changed.
buf = new Buffer(1234);
console.log(buf.length);
buf.write("some string", "ascii", 0);
console.log(buf.length);
// 1234
// 1234Does a memcpy() between buffers.
Example: build two Buffers, then copy buf1 from byte 16 through byte 19
into buf2, starting at the 8th byte in buf2.
buf1 = new Buffer(26);
buf2 = new Buffer(26);
for (var i = 0 ; i < 26 ; i++) {
buf1[i] = i + 97; // 97 is ASCII a
buf2[i] = 33; // ASCII !
}
buf1.copy(buf2, 8, 16, 20);
console.log(buf2.toString('ascii', 0, 25));
// !!!!!!!!qrst!!!!!!!!!!!!!Returns a new buffer which references the
same memory as the old, but offset and cropped by the start and end
indexes.
Modifying the new buffer slice will modify memory in the original buffer!
Example: build a Buffer with the ASCII alphabet, take a slice, then modify one byte from the original Buffer.
var buf1 = new Buffer(26);
for (var i = 0 ; i < 26 ; i++) {
buf1[i] = i + 97; // 97 is ASCII a
}
var buf2 = buf1.slice(0, 3);
console.log(buf2.toString('ascii', 0, buf2.length));
buf1[0] = 33;
console.log(buf2.toString('ascii', 0, buf2.length));
// abc
// !bcA stream is an abstract interface implemented by various objects in Node.
For example a request to an HTTP server is a stream, as is stdout. Streams
are readable, writable, or both. All streams are instances of EventEmitter.
A Readable Stream has the following methods, members, and events.
function (data) { }
The 'data' event emits either a Buffer (by default) or a string if
setEncoding() was used.
function () { }
Emitted when the stream has received an EOF (FIN in TCP terminology).
Indicates that no more 'data' events will happen. If the stream is also
writable, it may be possible to continue writing.
function (exception) { }
Emitted if there was an error receiving data.
function () { }
Emitted when the underlying file descriptor has been closed. Not all streams
will emit this. (For example, an incoming HTTP request will not emit
'close'.)
function (fd) { }
Emitted when a file descriptor is received on the stream. Only UNIX streams support this functionality; all others will simply never emit this event.
A boolean that is true by default, but turns false after an 'error'
occurred, the stream came to an 'end', or destroy() was called.
Makes the data event emit a string instead of a Buffer. encoding can be
'utf8', 'ascii', or 'base64'.
Pauses the incoming 'data' events.
Resumes the incoming 'data' events after a pause().
Closes the underlying file descriptor. Stream will not emit any more events.
After the write queue is drained, close the file descriptor.
This is a Stream.prototype method available on all Streams.
Connects this read stream to destination WriteStream. Incoming
data on this stream gets written to destination. The destination and source
streams are kept in sync by pausing and resuming as necessary.
Emulating the Unix cat command:
process.stdin.resume();
process.stdin.pipe(process.stdout);By default end() is called on the destination when the source stream emits
end, so that destination is no longer writable. Pass { end: false } as
options to keep the destination stream open.
This keeps process.stdout open so that "Goodbye" can be written at the end.
process.stdin.resume();
process.stdin.pipe(process.stdout, { end: false });
process.stdin.on("end", function() {
process.stdout.write("Goodbye\n");
});NOTE: If the source stream does not support pause() and resume(), this function
adds simple definitions which simply emit 'pause' and 'resume' events on
the source stream.
A Writable Stream has the following methods, members, and events.
function () { }
Emitted after a write() method was called that returned false to
indicate that it is safe to write again.
function (exception) { }
Emitted on error with the exception exception.
function () { }
Emitted when the underlying file descriptor has been closed.
function (src) { }
Emitted when the stream is passed to a readable stream's pipe method.
A boolean that is true by default, but turns false after an 'error'
occurred or end() / destroy() was called.
Writes string with the given encoding to the stream. Returns true if
the string has been flushed to the kernel buffer. Returns false to
indicate that the kernel buffer is full, and the data will be sent out in
the future. The 'drain' event will indicate when the kernel buffer is
empty again. The encoding defaults to 'utf8'.
If the optional fd parameter is specified, it is interpreted as an integral
file descriptor to be sent over the stream. This is only supported for UNIX
streams, and is silently ignored otherwise. When writing a file descriptor in
this manner, closing the descriptor before the stream drains risks sending an
invalid (closed) FD.
Same as the above except with a raw buffer.
Terminates the stream with EOF or FIN.
Sends string with the given encoding and terminates the stream with EOF
or FIN. This is useful to reduce the number of packets sent.
Same as above but with a buffer.
Closes the underlying file descriptor. Stream will not emit any more events.
After the write queue is drained, close the file descriptor. destroySoon()
can still destroy straight away, as long as there is no data left in the queue
for writes.
Use require('crypto') to access this module.
The crypto module requires OpenSSL to be available on the underlying platform. It offers a way of encapsulating secure credentials to be used as part of a secure HTTPS net or http connection.
It also offers a set of wrappers for OpenSSL's hash, hmac, cipher, decipher, sign and verify methods.
Creates a credentials object, with the optional details being a dictionary with keys:
key : a string holding the PEM encoded private keycert : a string holding the PEM encoded certificateca : either a string or list of strings of PEM encoded CA certificates to trust.If no 'ca' details are given, then node.js will use the default publicly trusted list of CAs as given in http://mxr.mozilla.org/mozilla/source/security/nss/lib/ckfw/builtins/certdata.txt.
Creates and returns a hash object, a cryptographic hash with the given algorithm which can be used to generate hash digests.
algorithm is dependent on the available algorithms supported by the version
of OpenSSL on the platform. Examples are 'sha1', 'md5', 'sha256', 'sha512', etc.
On recent releases, openssl list-message-digest-algorithms will display the available digest algorithms.
Example: this program that takes the sha1 sum of a file
var filename = process.argv[2];
var crypto = require('crypto');
var fs = require('fs');
var shasum = crypto.createHash('sha1');
var s = fs.ReadStream(filename);
s.on('data', function(d) {
shasum.update(d);
});
s.on('end', function() {
var d = shasum.digest('hex');
console.log(d + ' ' + filename);
});Updates the hash content with the given data.
This can be called many times with new data as it is streamed.
Calculates the digest of all of the passed data to be hashed.
The encoding can be 'hex', 'binary' or 'base64'.
Creates and returns a hmac object, a cryptographic hmac with the given algorithm and key.
algorithm is dependent on the available algorithms supported by OpenSSL - see createHash above.
key is the hmac key to be used.
Update the hmac content with the given data.
This can be called many times with new data as it is streamed.
Calculates the digest of all of the passed data to the hmac.
The encoding can be 'hex', 'binary' or 'base64'.
Creates and returns a cipher object, with the given algorithm and key.
algorithm is dependent on OpenSSL, examples are 'aes192', etc.
On recent releases, openssl list-cipher-algorithms will display the available cipher algorithms.
Updates the cipher with data, the encoding of which is given in input_encoding
and can be 'utf8', 'ascii' or 'binary'. The output_encoding specifies
the output format of the enciphered data, and can be 'binary', 'base64' or 'hex'.
Returns the enciphered contents, and can be called many times with new data as it is streamed.
Returns any remaining enciphered contents, with output_encoding being one of: 'binary', 'base64' or 'hex'.
Creates and returns a decipher object, with the given algorithm and key. This is the mirror of the cipher object above.
Updates the decipher with data, which is encoded in 'binary', 'base64' or 'hex'.
The output_decoding specifies in what format to return the deciphered plaintext: 'binary', 'ascii' or 'utf8'.
Returns any remaining plaintext which is deciphered,
with output_encoding being one of: 'binary', 'ascii' or 'utf8'.
Creates and returns a signing object, with the given algorithm.
On recent OpenSSL releases, openssl list-public-key-algorithms will display
the available signing algorithms. Examples are 'RSA-SHA256'.
Updates the signer object with data. This can be called many times with new data as it is streamed.
Calculates the signature on all the updated data passed through the signer.
private_key is a string containing the PEM encoded private key for signing.
Returns the signature in output_format which can be 'binary', 'hex' or 'base64'.
Creates and returns a verification object, with the given algorithm. This is the mirror of the signing object above.
Updates the verifier object with data. This can be called many times with new data as it is streamed.
Verifies the signed data by using the object and signature. object is a
string containing a PEM encoded object, which can be one of RSA public key,
DSA public key, or X.509 certificate. signature is the previously calculated
signature for the data, in the signature_format which can be 'binary',
'hex' or 'base64'.
Returns true or false depending on the validity of the signature for the data and public key.
Use require('tls') to access this module.
The tls module uses OpenSSL to provide Transport Layer Security and/or
Secure Socket Layer: encrypted stream communication.
TLS/SSL is a public/private key infrastructure. Each client and each server must have a private key. A private key is created like this
openssl genrsa -out ryans-key.pem 1024All severs and some clients need to have a certificate. Certificates are public keys signed by a Certificate Authority or self-signed. The first step to getting a certificate is to create a "Certificate Signing Request" (CSR) file. This is done with:
openssl req -new -key ryans-key.pem -out ryans-csr.pemTo create a self-signed certificate with the CSR, do this:
openssl x509 -req -in ryans-csr.pem -signkey ryans-key.pem -out ryans-cert.pemAlternatively you can send the CSR to a Certificate Authority for signing.
(TODO: docs on creating a CA, for now interested users should just look at
test/fixtures/keys/Makefile in the Node source code)
Creates a new client connection to the given port and host. (If host
defaults to localhost.) options should be an object which specifies
key: A string or Buffer containing the private key of the server in
PEM format. (Required)
cert: A string or Buffer containing the certificate key of the server in
PEM format.
ca: An array of strings or Buffers of trusted certificates. If this is
omitted several well known "root" CAs will be used, like VeriSign.
These are used to authorize connections.
tls.connect() returns a cleartext CryptoStream object.
After the TLS/SSL handshake the callback is called. The callback will be
called no matter if the server's certificate was authorized or not. It is up
to the user to test s.authorized to see if the server certificate was
signed by one of the specified CAs. If s.authorized === false then the error
can be found in s.authorizationError.
In the v0.4 branch no function exists for starting a TLS session on an
already existing TCP connection. This is possible it just requires a bit of
work. The technique is to use tls.createSecurePair() which returns two
streams: an encrypted stream and a plaintext stream. The encrypted stream is then
piped to the socket, the plaintext stream is what the user interacts with thereafter.
Here is some code that does it.
This class is a subclass of net.Server and has the same methods on it.
Instead of accepting just raw TCP connections, this accepts encrypted
connections using TLS or SSL.
Here is a simple example echo server:
var tls = require('tls');
var fs = require('fs');
var options = {
key: fs.readFileSync('server-key.pem'),
cert: fs.readFileSync('server-cert.pem')
};
tls.createServer(options, function (s) {
s.write("welcome!\n");
s.pipe(s);
}).listen(8000);You can test this server by connecting to it with openssl s_client:
openssl s_client -connect 127.0.0.1:8000This is a constructor for the tls.Server class. The options object
has these possibilities:
key: A string or Buffer containing the private key of the server in
PEM format. (Required)
cert: A string or Buffer containing the certificate key of the server in
PEM format. (Required)
ca: An array of strings or Buffers of trusted certificates. If this is
omitted several well known "root" CAs will be used, like VeriSign.
These are used to authorize connections.
requestCert: If true the server will request a certificate from
clients that connect and attempt to verify that certificate. Default:
false.
rejectUnauthorized: If true the server will reject any connection
which is not authorized with the list of supplied CAs. This option only
has an effect if requestCert is true. Default: false.
function (cleartextStream) {}
This event is emitted after a new connection has been successfully
handshaked. The argument is a duplex instance of stream.Stream. It has all
the common stream methods and events.
cleartextStream.authorized is a boolean value which indicates if the
client has verified by one of the supplied certificate authorities for the
server. If cleartextStream.authorized is false, then
cleartextStream.authorizationError is set to describe how authorization
failed. Implied but worth mentioning: depending on the settings of the TLS
server, you unauthorized connections may be accepted.
Begin accepting connections on the specified port and host. If the
host is omitted, the server will accept connections directed to any
IPv4 address (INADDR_ANY).
This function is asynchronous. The last parameter callback will be called
when the server has been bound.
See net.Server for more information.
Stops the server from accepting new connections. This function is
asynchronous, the server is finally closed when the server emits a 'close'
event.
Set this property to reject connections when the server's connection count gets high.
The number of concurrent connections on the server.
File I/O is provided by simple wrappers around standard POSIX functions. To
use this module do require('fs'). All the methods have asynchronous and
synchronous forms.
The asynchronous form always take a completion callback as its last argument.
The arguments passed to the completion callback depend on the method, but the
first argument is always reserved for an exception. If the operation was
completed successfully, then the first argument will be null or undefined.
Here is an example of the asynchronous version:
var fs = require('fs');
fs.unlink('/tmp/hello', function (err) {
if (err) throw err;
console.log('successfully deleted /tmp/hello');
});Here is the synchronous version:
var fs = require('fs');
fs.unlinkSync('/tmp/hello')
console.log('successfully deleted /tmp/hello');With the asynchronous methods there is no guaranteed ordering. So the following is prone to error:
fs.rename('/tmp/hello', '/tmp/world', function (err) {
if (err) throw err;
console.log('renamed complete');
});
fs.stat('/tmp/world', function (err, stats) {
if (err) throw err;
console.log('stats: ' + JSON.stringify(stats));
});It could be that fs.stat is executed before fs.rename.
The correct way to do this is to chain the callbacks.
fs.rename('/tmp/hello', '/tmp/world', function (err) {
if (err) throw err;
fs.stat('/tmp/world', function (err, stats) {
if (err) throw err;
console.log('stats: ' + JSON.stringify(stats));
});
});In busy processes, the programmer is strongly encouraged to use the asynchronous versions of these calls. The synchronous versions will block the entire process until they complete--halting all connections.
Relative path to filename can be used, remember however that this path will be relative
to process.cwd().
Asynchronous rename(2). No arguments other than a possible exception are given to the completion callback.
Synchronous rename(2).
Asynchronous ftruncate(2). No arguments other than a possible exception are given to the completion callback.
Synchronous ftruncate(2).
Asycnronous chown(2). No arguments other than a possible exception are given to the completion callback.
Synchronous chown(2).
Asycnronous fchown(2). No arguments other than a possible exception are given to the completion callback.
Synchronous fchown(2).
Asycnronous lchown(2). No arguments other than a possible exception are given to the completion callback.
Synchronous lchown(2).
Asynchronous chmod(2). No arguments other than a possible exception are given to the completion callback.
Synchronous chmod(2).
Asynchronous fchmod(2). No arguments other than a possible exception are given to the completion callback.
Synchronous fchmod(2).
Asynchronous lchmod(2). No arguments other than a possible exception are given to the completion callback.
Synchronous lchmod(2).
Asynchronous stat(2). The callback gets two arguments (err, stats) where
stats is a `fs.Stats` object. It looks like this:
{ dev: 2049,
ino: 305352,
mode: 16877,
nlink: 12,
uid: 1000,
gid: 1000,
rdev: 0,
size: 4096,
blksize: 4096,
blocks: 8,
atime: '2009-06-29T11:11:55Z',
mtime: '2009-06-29T11:11:40Z',
ctime: '2009-06-29T11:11:40Z' }See the fs.Stats section below for more information.
Asynchronous lstat(2). The callback gets two arguments (err, stats) where
stats is a fs.Stats object. lstat() is identical to stat(), except that if
path is a symbolic link, then the link itself is stat-ed, not the file that it
refers to.
Asynchronous fstat(2). The callback gets two arguments (err, stats) where
stats is a fs.Stats object. fstat() is identical to stat(), except that
the file to be stat-ed is specified by the file descriptor fd.
Synchronous stat(2). Returns an instance of fs.Stats.
Synchronous lstat(2). Returns an instance of fs.Stats.
Synchronous fstat(2). Returns an instance of fs.Stats.
Asynchronous link(2). No arguments other than a possible exception are given to the completion callback.
Synchronous link(2).
Asynchronous symlink(2). No arguments other than a possible exception are given to the completion callback.
Synchronous symlink(2).
Asynchronous readlink(2). The callback gets two arguments (err,
resolvedPath).
Synchronous readlink(2). Returns the resolved path.
Asynchronous realpath(2). The callback gets two arguments (err,
resolvedPath).
Synchronous realpath(2). Returns the resolved path.
Asynchronous unlink(2). No arguments other than a possible exception are given to the completion callback.
Synchronous unlink(2).
Asynchronous rmdir(2). No arguments other than a possible exception are given to the completion callback.
Synchronous rmdir(2).
Asynchronous mkdir(2). No arguments other than a possible exception are given to the completion callback.
Synchronous mkdir(2).
Asynchronous readdir(3). Reads the contents of a directory.
The callback gets two arguments (err, files) where files is an array of
the names of the files in the directory excluding '.' and '..'.
Synchronous readdir(3). Returns an array of filenames excluding '.' and
'..'.
Asynchronous close(2). No arguments other than a possible exception are given to the completion callback.
Synchronous close(2).
Asynchronous file open. See open(2). flags can be:
'r' - Open file for reading.
An exception occurs if the file does not exist.
'r+' - Open file for reading and writing.
An exception occurs if the file does not exist.
'w' - Open file for writing.
The file is created (if it does not exist) or truncated (if it exists).
'w+' - Open file for reading and writing.
The file is created (if it does not exist) or truncated (if it exists).
'a' - Open file for appending.
The file is created if it does not exist.
'a+' - Open file for reading and appending.
The file is created if it does not exist.
mode defaults to 0666. The callback gets two arguments (err, fd).
Synchronous open(2).
Write buffer to the file specified by fd.
offset and length determine the part of the buffer to be written.
position refers to the offset from the beginning of the file where this data
should be written. If position is null, the data will be written at the
current position.
See pwrite(2).
The callback will be given three arguments (err, written, buffer) where written
specifies how many bytes were written into buffer.
Note that it is unsafe to use fs.write multiple times on the same file
without waiting for the callback. For this scenario,
fs.createWriteStream is strongly recommended.
Synchronous version of buffer-based fs.write(). Returns the number of bytes
written.
Synchronous version of string-based fs.write(). Returns the number of bytes
written.
Read data from the file specified by fd.
buffer is the buffer that the data will be written to.
offset is offset within the buffer where writing will start.
length is an integer specifying the number of bytes to read.
position is an integer specifying where to begin reading from in the file.
If position is null, data will be read from the current file position.
The callback is given the three arguments, (err, bytesRead, buffer).
Synchronous version of buffer-based fs.read. Returns the number of
bytesRead.
Synchronous version of string-based fs.read. Returns the number of
bytesRead.
Asynchronously reads the entire contents of a file. Example:
fs.readFile('/etc/passwd', function (err, data) {
if (err) throw err;
console.log(data);
});The callback is passed two arguments (err, data), where data is the
contents of the file.
If no encoding is specified, then the raw buffer is returned.
Synchronous version of fs.readFile. Returns the contents of the filename.
If encoding is specified then this function returns a string. Otherwise it
returns a buffer.
Asynchronously writes data to a file, replacing the file if it already exists.
data can be a string or a buffer.
Example:
fs.writeFile('message.txt', 'Hello Node', function (err) {
if (err) throw err;
console.log('It\'s saved!');
});The synchronous version of fs.writeFile.
Watch for changes on filename. The callback listener will be called each
time the file is accessed.
The second argument is optional. The options if provided should be an object
containing two members a boolean, persistent, and interval, a polling
value in milliseconds. The default is { persistent: true, interval: 0 }.
The listener gets two arguments the current stat object and the previous
stat object:
fs.watchFile(f, function (curr, prev) {
console.log('the current mtime is: ' + curr.mtime);
console.log('the previous mtime was: ' + prev.mtime);
});These stat objects are instances of fs.Stat.
If you want to be notified when the file was modified, not just accessed
you need to compare curr.mtime and `prev.mtime.
Stop watching for changes on filename.
Objects returned from fs.stat() and fs.lstat() are of this type.
stats.isFile()stats.isDirectory()stats.isBlockDevice()stats.isCharacterDevice()stats.isSymbolicLink() (only valid with fs.lstat())stats.isFIFO()stats.isSocket()ReadStream is a Readable Stream.
function (fd) { }
fd is the file descriptor used by the ReadStream.
Returns a new ReadStream object (See Readable Stream).
options is an object with the following defaults:
{ flags: 'r',
encoding: null,
fd: null,
mode: 0666,
bufferSize: 64 * 1024
}options can include start and end values to read a range of bytes from
the file instead of the entire file. Both start and end are inclusive and
start at 0.
An example to read the last 10 bytes of a file which is 100 bytes long:
fs.createReadStream('sample.txt', {start: 90, end: 99});WriteStream is a Writable Stream.
function (fd) { }
fd is the file descriptor used by the WriteStream.
Returns a new WriteStream object (See Writable Stream).
options is an object with the following defaults:
{ flags: 'w',
encoding: null,
mode: 0666 }This module contains utilities for dealing with file paths. Use
require('path') to use it. It provides the following methods:
Normalize a string path, taking care of '..' and '.' parts.
When multiple slashes are found, they're replaces by a single one; when the path contains a trailing slash, it is preserved. On windows backslashes are used.
Example:
path.normalize('/foo/bar//baz/asdf/quux/..')
// returns
'/foo/bar/baz/asdf'Join all arguments together and normalize the resulting path.
Example:
node> require('path').join(
... '/foo', 'bar', 'baz/asdf', 'quux', '..')
'/foo/bar/baz/asdf'Resolves to to an absolute path.
If to isn't already absolute from arguments are prepended in right to left
order, until an absolute path is found. If after using all from paths still
no absolute path is found, the current working directory is used as well. The
resulting path is normalized, and trailing slashes are removed unless the path
gets resolved to the root directory.
Another way to think of it is as a sequence of cd commands in a shell.
path.resolve('foo/bar', '/tmp/file/', '..', 'a/../subfile')Is similar to:
cd foo/bar
cd /tmp/file/
cd ..
cd a/../subfile
pwdThe difference is that the different paths don't need to exist and may also be files.
Examples:
path.resolve('/foo/bar', './baz')
// returns
'/foo/bar/baz'
path.resolve('/foo/bar', '/tmp/file/')
// returns
'/tmp/file'
path.resolve('wwwroot', 'static_files/png/', '../gif/image.gif')
// if currently in /home/myself/node, it returns
'/home/myself/node/wwwroot/static_files/gif/image.gif'Return the directory name of a path. Similar to the Unix dirname command.
Example:
path.dirname('/foo/bar/baz/asdf/quux')
// returns
'/foo/bar/baz/asdf'Return the last portion of a path. Similar to the Unix basename command.
Example:
path.basename('/foo/bar/baz/asdf/quux.html')
// returns
'quux.html'
path.basename('/foo/bar/baz/asdf/quux.html', '.html')
// returns
'quux'Return the extension of the path. Everything after the last '.' in the last portion of the path. If there is no '.' in the last portion of the path or the only '.' is the first character, then it returns an empty string. Examples:
path.extname('index.html')
// returns
'.html'
path.extname('index')
// returns
''Test whether or not the given path exists. Then, call the callback argument
with either true or false. Example:
path.exists('/etc/passwd', function (exists) {
util.debug(exists ? "it's there" : "no passwd!");
});Synchronous version of path.exists.
The net module provides you with an asynchronous network wrapper. It contains
methods for creating both servers and clients (called streams). You can include
this module with require("net");
Creates a new TCP server. The connectionListener argument is
automatically set as a listener for the 'connection' event.
options is an object with the following defaults:
{ allowHalfOpen: false
}If allowHalfOpen is true, then the socket won't automatically send FIN
packet when the other end of the socket sends a FIN packet. The socket becomes
non-readable, but still writable. You should call the end() method explicitly.
See 'end' event for more information.
Construct a new socket object and opens a socket to the given location. When
the socket is established the 'connect' event will be emitted.
The arguments for this method change the type of connection:
net.createConnection(port, [host])
Creates a TCP connection to port on host. If host is omitted, localhost
will be assumed.
net.createConnection(path)
Creates unix socket connection to path
This class is used to create a TCP or UNIX server.
Here is an example of a echo server which listens for connections on port 8124:
var net = require('net');
var server = net.createServer(function (c) {
c.write('hello\r\n');
c.pipe(c);
});
server.listen(8124, 'localhost');Test this by using telnet:
telnet localhost 8124To listen on the socket /tmp/echo.sock the last line would just be
changed to
server.listen('/tmp/echo.sock');Use nc to connect to a UNIX domain socket server:
nc -U /tmp/echo.socknet.Server is an EventEmitter with the following events:
Begin accepting connections on the specified port and host. If the
host is omitted, the server will accept connections directed to any
IPv4 address (INADDR_ANY).
This function is asynchronous. The last parameter callback will be called
when the server has been bound.
One issue some users run into is getting EADDRINUSE errors. Meaning
another server is already running on the requested port. One way of handling this
would be to wait a second and the try again. This can be done with
server.on('error', function (e) {
if (e.code == 'EADDRINUSE') {
console.log('Address in use, retrying...');
setTimeout(function () {
server.close();
server.listen(PORT, HOST);
}, 1000);
}
});(Note: All sockets in Node are set SO_REUSEADDR already)
Start a UNIX socket server listening for connections on the given path.
This function is asynchronous. The last parameter callback will be called
when the server has been bound.
Start a server listening for connections on the given file descriptor.
This file descriptor must have already had the bind(2) and listen(2) system
calls invoked on it. Additionally, it must be set non-blocking; try
fcntl(fd, F_SETFL, O_NONBLOCK).
Stop accepting connections for the given number of milliseconds (default is one second). This could be useful for throttling new connections against DoS attacks or other oversubscription.
Stops the server from accepting new connections. This function is
asynchronous, the server is finally closed when the server emits a 'close'
event.
Returns the bound address and port of the server as reported by the operating system.
Useful to find which port was assigned when giving getting an OS-assigned address.
Returns an object with two properties, e.g. {"address":"127.0.0.1", "port":2121}
Example:
var server = net.createServer(function (socket) {
socket.end("goodbye\n");
});
// grab a random port.
server.listen(function() {
address = server.address();
console.log("opened server on %j", address);
});Set this property to reject connections when the server's connection count gets high.
The number of concurrent connections on the server.
function (socket) {}
Emitted when a new connection is made. socket is an instance of
net.Socket.
function () {}
Emitted when the server closes.
This object is an abstraction of of a TCP or UNIX socket. net.Socket
instances implement a duplex Stream interface. They can be created by the
user and used as a client (with connect()) or they can be created by Node
and passed to the user through the 'connection' event of a server.
net.Socket instances are EventEmitters with the following events:
Construct a new socket object.
options is an object with the following defaults:
{ fd: null
type: null
allowHalfOpen: false
}fd allows you to specify the existing file descriptor of socket. type
specified underlying protocol. It can be 'tcp4', 'tcp6', or 'unix'.
About allowHalfOpen, refer to createServer() and 'end' event.
Opens the connection for a given socket. If port and host are given,
then the socket will be opened as a TCP socket, if host is omitted,
localhost will be assumed. If a path is given, the socket will be
opened as a unix socket to that path.
Normally this method is not needed, as net.createConnection opens the
socket. Use this only if you are implementing a custom Socket or if a
Socket is closed and you want to reuse it to connect to another server.
This function is asynchronous. When the 'connect' event is emitted the
socket is established. If there is a problem connecting, the 'connect'
event will not be emitted, the 'error' event will be emitted with
the exception.
The callback parameter will be added as an listener for the 'connect'
event.
net.Socket has the property that socket.write() always works. This is to
help users get up an running quickly. The computer cannot necessarily keep up
with the amount of data that is written to a socket - the network connection simply
might be too slow. Node will internally queue up the data written to a socket and
send it out over the wire when it is possible. (Internally it is polling on
the socket's file descriptor for being writable).
The consequence of this internal buffering is that memory may grow. This property shows the number of characters currently buffered to be written. (Number of characters is approximately equal to the number of bytes to be written, but the buffer may contain strings, and the strings are lazily encoded, so the exact number of bytes is not known.)
Users who experience large or growing bufferSize should attempt to
"throttle" the data flows in their program with pause() and resume()`.
Sets the encoding (either 'ascii', 'utf8', or 'base64') for data that is
received.
This function has been removed in v0.3. It used to upgrade the connection to SSL/TLS. See the TLS section for the new API.
Sends data on the socket. The second parameter specifies the encoding in the case of a string--it defaults to UTF8 encoding.
Returns true if the entire data was flushed successfully to the kernel
buffer. Returns false if all or part of the data was queued in user memory.
'drain' will be emitted when the buffer is again free.
The optional callback parameter will be executed when the data is finally
written out - this may not be immediately.
For UNIX sockets, it is possible to send a file descriptor through the
socket. Simply add the fileDescriptor argument and listen for the 'fd'
event on the other end.
Half-closes the socket. I.E., it sends a FIN packet. It is possible the server will still send some data.
If data is specified, it is equivalent to calling socket.write(data, encoding)
followed by socket.end().
Ensures that no more I/O activity happens on this socket. Only necessary in case of errors (parse error or so).
Pauses the reading of data. That is, 'data' events will not be emitted.
Useful to throttle back an upload.
Resumes reading after a call to pause().
Sets the socket to timeout after timeout milliseconds of inactivity on
the socket. By default net.Socket do not have a timeout.
When an idle timeout is triggered the socket will receive a 'timeout'
event but the connection will not be severed. The user must manually end()
or destroy() the socket.
If timeout is 0, then the existing idle timeout is disabled.
The optional callback parameter will be added as a one time listener for the 'timeout' event.
Disables the Nagle algorithm. By default TCP connections use the Nagle
algorithm, they buffer data before sending it off. Setting noDelay will
immediately fire off data each time socket.write() is called.
Enable/disable keep-alive functionality, and optionally set the initial
delay before the first keepalive probe is sent on an idle socket.
Set initialDelay (in milliseconds) to set the delay between the last
data packet received and the first keepalive probe. Setting 0 for
initialDelay will leave the value unchanged from the default
(or previous) setting.
Returns the bound address and port of the socket as reported by the operating system.
Returns an object with two properties, e.g. {"address":"192.168.57.1", "port":62053}
The string representation of the remote IP address. For example,
'74.125.127.100' or '2001:4860:a005::68'.
This member is only present in server-side connections.
function () { }
Emitted when a socket connection successfully is established.
See connect().
function (data) { }
Emitted when data is received. The argument data will be a Buffer or
String. Encoding of data is set by socket.setEncoding().
(See the Readable Stream section for more information.)
function () { }
Emitted when the other end of the socket sends a FIN packet.
By default (allowHalfOpen == false) the socket will destroy its file
descriptor once it has written out its pending write queue. However, by
setting allowHalfOpen == true the socket will not automatically end()
its side allowing the user to write arbitrary amounts of data, with the
caveat that the user is required to end() their side now.
function () { }
Emitted if the socket times out from inactivity. This is only to notify that the socket has been idle. The user must manually close the connection.
See also: socket.setTimeout()
function () { }
Emitted when the write buffer becomes empty. Can be used to throttle uploads.
function (exception) { }
Emitted when an error occurs. The 'close' event will be called directly
following this event.
function (had_error) { }
Emitted once the socket is fully closed. The argument had_error is a boolean
which says if the socket was closed due to a transmission error.
Tests if input is an IP address. Returns 0 for invalid strings, returns 4 for IP version 4 addresses, and returns 6 for IP version 6 addresses.
Returns true if input is a version 4 IP address, otherwise returns false.
Returns true if input is a version 6 IP address, otherwise returns false.
Datagram sockets are available through require('dgram'). Datagrams are most commonly
handled as IP/UDP messages but they can also be used over Unix domain sockets.
function (msg, rinfo) { }
Emitted when a new datagram is available on a socket. msg is a Buffer and rinfo is
an object with the sender's address information and the number of bytes in the datagram.
function () { }
Emitted when a socket starts listening for datagrams. This happens as soon as UDP sockets
are created. Unix domain sockets do not start listening until calling bind() on them.
function () { }
Emitted when a socket is closed with close(). No new message events will be emitted
on this socket.
Creates a datagram socket of the specified types. Valid types are:
udp4, udp6, and unix_dgram.
Takes an optional callback which is added as a listener for message events.
For Unix domain datagram sockets, the destination address is a pathname in the filesystem.
An optional callback may be supplied that is invoked after the sendto call is completed
by the OS. It is not safe to re-use buf until the callback is invoked. Note that
unless the socket is bound to a pathname with bind() there is no way to receive messages
on this socket.
Example of sending a message to syslogd on OSX via Unix domain socket /var/run/syslog:
var dgram = require('dgram');
var message = new Buffer("A message to log.");
var client = dgram.createSocket("unix_dgram");
client.send(message, 0, message.length, "/var/run/syslog",
function (err, bytes) {
if (err) {
throw err;
}
console.log("Wrote " + bytes + " bytes to socket.");
});For UDP sockets, the destination port and IP address must be specified. A string
may be supplied for the address parameter, and it will be resolved with DNS. An
optional callback may be specified to detect any DNS errors and when buf may be
re-used. Note that DNS lookups will delay the time that a send takes place, at
least until the next tick. The only way to know for sure that a send has taken place
is to use the callback.
Example of sending a UDP packet to a random port on localhost;
var dgram = require('dgram');
var message = new Buffer("Some bytes");
var client = dgram.createSocket("udp4");
client.send(message, 0, message.length, 41234, "localhost");
client.close();For Unix domain datagram sockets, start listening for incoming datagrams on a
socket specified by path. Note that clients may send() without bind(),
but no datagrams will be received without a bind().
Example of a Unix domain datagram server that echoes back all messages it receives:
var dgram = require("dgram");
var serverPath = "/tmp/dgram_server_sock";
var server = dgram.createSocket("unix_dgram");
server.on("message", function (msg, rinfo) {
console.log("got: " + msg + " from " + rinfo.address);
server.send(msg, 0, msg.length, rinfo.address);
});
server.on("listening", function () {
console.log("server listening " + server.address().address);
})
server.bind(serverPath);Example of a Unix domain datagram client that talks to this server:
var dgram = require("dgram");
var serverPath = "/tmp/dgram_server_sock";
var clientPath = "/tmp/dgram_client_sock";
var message = new Buffer("A message at " + (new Date()));
var client = dgram.createSocket("unix_dgram");
client.on("message", function (msg, rinfo) {
console.log("got: " + msg + " from " + rinfo.address);
});
client.on("listening", function () {
console.log("client listening " + client.address().address);
client.send(message, 0, message.length, serverPath);
});
client.bind(clientPath);For UDP sockets, listen for datagrams on a named port and optional address. If
address is not specified, the OS will try to listen on all addresses.
Example of a UDP server listening on port 41234:
var dgram = require("dgram");
var server = dgram.createSocket("udp4");
server.on("message", function (msg, rinfo) {
console.log("server got: " + msg + " from " +
rinfo.address + ":" + rinfo.port);
});
server.on("listening", function () {
var address = server.address();
console.log("server listening " +
address.address + ":" + address.port);
});
server.bind(41234);
// server listening 0.0.0.0:41234Close the underlying socket and stop listening for data on it. UDP sockets
automatically listen for messages, even if they did not call bind().
Returns an object containing the address information for a socket. For UDP sockets,
this object will contain address and port. For Unix domain sockets, it will contain
only address.
Sets or clears the SO_BROADCAST socket option. When this option is set, UDP packets
may be sent to a local interface's broadcast address.
Sets the IP_TTL socket option. TTL stands for "Time to Live," but in this context it
specifies the number of IP hops that a packet is allowed to go through. Each router or
gateway that forwards a packet decrements the TTL. If the TTL is decremented to 0 by a
router, it will not be forwarded. Changing TTL values is typically done for network
probes or when multicasting.
The argument to setTTL() is a number of hops between 1 and 255. The default on most
systems is 64.
Sets the IP_MULTICAST_TTL socket option. TTL stands for "Time to Live," but in this
context it specifies the number of IP hops that a packet is allowed to go through,
specifically for multicast traffic. Each router or gateway that forwards a packet
decrements the TTL. If the TTL is decremented to 0 by a router, it will not be forwarded.
The argument to setMulticastTTL() is a number of hops between 0 and 255. The default on most
systems is 64.
Sets or clears the IP_MULTICAST_LOOP socket option. When this option is set, multicast
packets will also be received on the local interface.
Tells the kernel to join a multicast group with IP_ADD_MEMBERSHIP socket option.
If multicastInterface is not specified, the OS will try to add membership to all valid
interfaces.
Opposite of addMembership - tells the kernel to leave a multicast group with
IP_DROP_MEMBERSHIP socket option. This is automatically called by the kernel
when the socket is closed or process terminates, so most apps will never need to call
this.
If multicastInterface is not specified, the OS will try to drop membership to all valid
interfaces.
Use require('dns') to access this module.
Here is an example which resolves 'www.google.com' then reverse
resolves the IP addresses which are returned.
var dns = require('dns');
dns.resolve4('www.google.com', function (err, addresses) {
if (err) throw err;
console.log('addresses: ' + JSON.stringify(addresses));
addresses.forEach(function (a) {
dns.reverse(a, function (err, domains) {
if (err) {
console.log('reverse for ' + a + ' failed: ' +
err.message);
} else {
console.log('reverse for ' + a + ': ' +
JSON.stringify(domains));
}
});
});
});Resolves a domain (e.g. 'google.com') into the first found A (IPv4) or
AAAA (IPv6) record.
The callback has arguments (err, address, family). The address argument
is a string representation of a IP v4 or v6 address. The family argument
is either the integer 4 or 6 and denotes the family of address (not
necessarily the value initially passed to lookup).
Resolves a domain (e.g. 'google.com') into an array of the record types
specified by rrtype. Valid rrtypes are A (IPV4 addresses), AAAA (IPV6
addresses), MX (mail exchange records), TXT (text records), SRV (SRV
records), PTR (used for reverse IP lookups), NS (name server records)
and CNAME (canonical name records).
The callback has arguments (err, addresses). The type of each item
in addresses is determined by the record type, and described in the
documentation for the corresponding lookup methods below.
On error, err would be an instanceof Error object, where err.errno is
one of the error codes listed below and err.message is a string describing
the error in English.
The same as dns.resolve(), but only for IPv4 queries (A records).
addresses is an array of IPv4 addresses (e.g.
['74.125.79.104', '74.125.79.105', '74.125.79.106']).
The same as dns.resolve4() except for IPv6 queries (an AAAA query).
The same as dns.resolve(), but only for mail exchange queries (MX records).
addresses is an array of MX records, each with a priority and an exchange
attribute (e.g. [{'priority': 10, 'exchange': 'mx.example.com'},...]).
The same as dns.resolve(), but only for text queries (TXT records).
addresses is an array of the text records available for domain (e.g.,
['v=spf1 ip4:0.0.0.0 ~all']).
The same as dns.resolve(), but only for service records (SRV records).
addresses is an array of the SRV records available for domain. Properties
of SRV records are priority, weight, port, and name (e.g.,
[{'priority': 10, {'weight': 5, 'port': 21223, 'name': 'service.example.com'}, ...]).
Reverse resolves an ip address to an array of domain names.
The callback has arguments (err, domains).
The same as dns.resolve(), but only for name server records (NS records).
addresses is an array of the name server records available for domain
(e.g., ['ns1.example.com', 'ns2.example.com']).
The same as dns.resolve(), but only for canonical name records (CNAME
records). addresses is an array of the canonical name records available for
domain (e.g., ['bar.example.com']).
If there an an error, err will be non-null and an instanceof the Error
object.
Each DNS query can return an error code.
dns.TEMPFAIL: timeout, SERVFAIL or similar.dns.PROTOCOL: got garbled reply.dns.NXDOMAIN: domain does not exists.dns.NODATA: domain exists but no data of reqd type.dns.NOMEM: out of memory while processing.dns.BADQUERY: the query is malformed.To use the HTTP server and client one must require('http').
The HTTP interfaces in Node are designed to support many features of the protocol which have been traditionally difficult to use. In particular, large, possibly chunk-encoded, messages. The interface is careful to never buffer entire requests or responses--the user is able to stream data.
HTTP message headers are represented by an object like this:
{ 'content-length': '123',
'content-type': 'text/plain',
'connection': 'keep-alive',
'accept': '*/*' }Keys are lowercased. Values are not modified.
In order to support the full spectrum of possible HTTP applications, Node's HTTP API is very low-level. It deals with stream handling and message parsing only. It parses a message into headers and body but it does not parse the actual headers or the body.
This is an EventEmitter with the following events:
function (request, response) { }
Emitted each time there is request. Note that there may be multiple requests
per connection (in the case of keep-alive connections).
request is an instance of http.ServerRequest and response is
an instance of http.ServerResponse
function (socket) { }
When a new TCP stream is established. socket is an object of type
net.Socket. Usually users will not want to access this event. The
stream can also be accessed at request.connection.
function (errno) { }
Emitted when the server closes.
function (request, response) { }
Emitted each time a request with an http Expect: 100-continue is received. If this event isn't listened for, the server will automatically respond with a 100 Continue as appropriate.
Handling this event involves calling response.writeContinue if the client
should continue to send the request body, or generating an appropriate HTTP
response (e.g., 400 Bad Request) if the client should not continue to send the
request body.
Note that when this event is emitted and handled, the request event will
not be emitted.
function (request, socket, head) { }
Emitted each time a client requests a http upgrade. If this event isn't listened for, then clients requesting an upgrade will have their connections closed.
request is the arguments for the http request, as it is in the request event.socket is the network socket between the server and client.head is an instance of Buffer, the first packet of the upgraded stream, this may be empty.After this event is emitted, the request's socket will not have a data
event listener, meaning you will need to bind to it in order to handle data
sent to the server on that socket.
function (exception) { }
If a client connection emits an 'error' event - it will forwarded here.
Returns a new web server object.
The requestListener is a function which is automatically
added to the 'request' event.
Begin accepting connections on the specified port and hostname. If the
hostname is omitted, the server will accept connections directed to any
IPv4 address (INADDR_ANY).
To listen to a unix socket, supply a filename instead of port and hostname.
This function is asynchronous. The last parameter callback will be called
when the server has been bound to the port.
Start a UNIX socket server listening for connections on the given path.
This function is asynchronous. The last parameter callback will be called
when the server has been bound.
Stops the server from accepting new connections.
This object is created internally by a HTTP server -- not by
the user -- and passed as the first argument to a 'request' listener.
This is an EventEmitter with the following events:
function (chunk) { }
Emitted when a piece of the message body is received.
Example: A chunk of the body is given as the single
argument. The transfer-encoding has been decoded. The
body chunk is a string. The body encoding is set with
request.setEncoding().
function () { }
Emitted exactly once for each request. After that, no more 'data' events
will be emitted on the request.
function (err) { }
Indicates that the underlaying connection was terminated before
response.end() was called or able to flush.
The err parameter is always present and indicates the reason for the timeout:
err.code === 'timeout' indicates that the underlaying connection timed out.
This may happen because all incoming connections have a default timeout of 2
minutes.
err.code === 'aborted' means that the client has closed the underlaying
connection prematurely.
Just like 'end', this event occurs only once per request, and no more 'data'
events will fire afterwards.
Note: 'close' can fire after 'end', but not vice versa.
The request method as a string. Read only. Example:
'GET', 'DELETE'.
Request URL string. This contains only the URL that is present in the actual HTTP request. If the request is:
GET /status?name=ryan HTTP/1.1\r\n
Accept: text/plain\r\n
\r\nThen request.url will be:
'/status?name=ryan'If you would like to parse the URL into its parts, you can use
require('url').parse(request.url). Example:
node> require('url').parse('/status?name=ryan')
{ href: '/status?name=ryan',
search: '?name=ryan',
query: 'name=ryan',
pathname: '/status' }If you would like to extract the params from the query string,
you can use the require('querystring').parse function, or pass
true as the second argument to require('url').parse. Example:
node> require('url').parse('/status?name=ryan', true)
{ href: '/status?name=ryan',
search: '?name=ryan',
query: { name: 'ryan' },
pathname: '/status' }Read only.
Read only; HTTP trailers (if present). Only populated after the 'end' event.
The HTTP protocol version as a string. Read only. Examples:
'1.1', '1.0'.
Also request.httpVersionMajor is the first integer and
request.httpVersionMinor is the second.
Set the encoding for the request body. Either 'utf8' or 'binary'. Defaults
to null, which means that the 'data' event will emit a Buffer object..
Pauses request from emitting events. Useful to throttle back an upload.
Resumes a paused request.
The net.Socket object associated with the connection.
With HTTPS support, use request.connection.verifyPeer() and request.connection.getPeerCertificate() to obtain the client's authentication details.
This object is created internally by a HTTP server--not by the user. It is
passed as the second parameter to the 'request' event. It is a Writable Stream.
Sends a HTTP/1.1 100 Continue message to the client, indicating that
the request body should be sent. See the checkContinue event on
Server.
Sends a response header to the request. The status code is a 3-digit HTTP
status code, like 404. The last argument, headers, are the response headers.
Optionally one can give a human-readable reasonPhrase as the second
argument.
Example:
var body = 'hello world';
response.writeHead(200, {
'Content-Length': body.length,
'Content-Type': 'text/plain' });This method must only be called once on a message and it must
be called before response.end() is called.
If you call response.write() or response.end() before calling this, the
implicit/mutable headers will be calculated and call this function for you.
Note: that Content-Length is given in bytes not characters. The above example
works because the string 'hello world' contains only single byte characters.
If the body contains higher coded characters then Buffer.byteLength()
should be used to determine the number of bytes in a given encoding.
When using implicit headers (not calling response.writeHead() explicitly), this property
controls the status code that will be send to the client when the headers get
flushed.
Example:
response.statusCode = 404;Sets a single header value for implicit headers. If this header already exists in the to-be-sent headers, it's value will be replaced. Use an array of strings here if you need to send multiple headers with the same name.
Example:
response.setHeader("Content-Type", "text/html");or
response.setHeader("Set-Cookie", ["type=ninja", "language=javascript"]);Reads out a header that's already been queued but not sent to the client. Note that the name is case insensitive. This can only be called before headers get implicitly flushed.
Example:
var contentType = response.getHeader('content-type');Removes a header that's queued for implicit sending.
Example:
response.removeHeader("Content-Encoding");If this method is called and response.writeHead() has not been called, it will
switch to implicit header mode and flush the implicit headers.
This sends a chunk of the response body. This method may be called multiple times to provide successive parts of the body.
chunk can be a string or a buffer. If chunk is a string,
the second parameter specifies how to encode it into a byte stream.
By default the encoding is 'utf8'.
Note: This is the raw HTTP body and has nothing to do with higher-level multi-part body encodings that may be used.
The first time response.write() is called, it will send the buffered
header information and the first body to the client. The second time
response.write() is called, Node assumes you're going to be streaming
data, and sends that separately. That is, the response is buffered up to the
first chunk of body.
This method adds HTTP trailing headers (a header but at the end of the message) to the response.
Trailers will only be emitted if chunked encoding is used for the response; if it is not (e.g., if the request was HTTP/1.0), they will be silently discarded.
Note that HTTP requires the Trailer header to be sent if you intend to
emit trailers, with a list of the header fields in its value. E.g.,
response.writeHead(200, { 'Content-Type': 'text/plain',
'Trailer': 'TraceInfo' });
response.write(fileData);
response.addTrailers({'Content-MD5': "7895bf4b8828b55ceaf47747b4bca667"});
response.end();This method signals to the server that all of the response headers and body
has been sent; that server should consider this message complete.
The method, response.end(), MUST be called on each
response.
If data is specified, it is equivalent to calling response.write(data, encoding)
followed by response.end().
Node maintains several connections per server to make HTTP requests. This function allows one to transparently issue requests.
Options:
host: A domain name or IP address of the server to issue the request to.port: Port of remote server.method: A string specifying the HTTP request method. Possible values:
'GET' (default), 'POST', 'PUT', and 'DELETE'.path: Request path. Should include query string and fragments if any.
E.G. '/index.html?page=12'headers: An object containing request headers.agent: Controls Agent behavior. Possible values:undefined (default): use default Agent for this host and port.Agent object: explicitly use the passed in Agent.false: explicitly generate a new Agent for this host and port. Agent will not be re-used.http.request() returns an instance of the http.ClientRequest
class. The ClientRequest instance is a writable stream. If one needs to
upload a file with a POST request, then write to the ClientRequest object.
Example:
var options = {
host: 'www.google.com',
port: 80,
path: '/upload',
method: 'POST'
};
var req = http.request(options, function(res) {
console.log('STATUS: ' + res.statusCode);
console.log('HEADERS: ' + JSON.stringify(res.headers));
res.setEncoding('utf8');
res.on('data', function (chunk) {
console.log('BODY: ' + chunk);
});
});
req.on('error', function(e) {
console.log('problem with request: ' + e.message);
});
// write data to request body
req.write('data\n');
req.write('data\n');
req.end();Note that in the example req.end() was called. With http.request() one
must always call req.end() to signify that you're done with the request -
even if there is no data being written to the request body.
If any error is encountered during the request (be that with DNS resolution,
TCP level errors, or actual HTTP parse errors) an 'error' event is emitted
on the returned request object.
There are a few special headers that should be noted.
Sending a 'Connection: keep-alive' will notify Node that the connection to the server should be persisted until the next request.
Sending a 'Content-length' header will disable the default chunked encoding.
Sending an 'Expect' header will immediately send the request headers.
Usually, when sending 'Expect: 100-continue', you should both set a timeout
and listen for the continue event. See RFC2616 Section 8.2.3 for more
information.
Since most requests are GET requests without bodies, Node provides this
convenience method. The only difference between this method and http.request() is
that it sets the method to GET and calls req.end() automatically.
Example:
var options = {
host: 'www.google.com',
port: 80,
path: '/index.html'
};
http.get(options, function(res) {
console.log("Got response: " + res.statusCode);
}).on('error', function(e) {
console.log("Got error: " + e.message);
});http.request() uses a special Agent for managing multiple connections to
an HTTP server. Normally Agent instances should not be exposed to user
code, however in certain situations it's useful to check the status of the
agent. The http.getAgent() function allows you to access the agents.
function (response, socket, head) { }
Emitted each time a server responds to a request with an upgrade. If this event isn't being listened for, clients receiving an upgrade header will have their connections closed.
A client server pair that show you how to listen for the upgrade event using http.getAgent:
var http = require('http');
var net = require('net');
// Create an HTTP server
var srv = http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('okay');
});
srv.on('upgrade', function(req, socket, upgradeHead) {
socket.write('HTTP/1.1 101 Web Socket Protocol Handshake\r\n' +
'Upgrade: WebSocket\r\n' +
'Connection: Upgrade\r\n' +
'\r\n\r\n');
socket.ondata = function(data, start, end) {
socket.write(data.toString('utf8', start, end), 'utf8'); // echo back
};
});
// now that server is running
srv.listen(1337, '127.0.0.1', function() {
// make a request
var agent = http.getAgent('127.0.0.1', 1337);
var options = {
agent: agent,
port: 1337,
host: '127.0.0.1',
headers: {
'Connection': 'Upgrade',
'Upgrade': 'websocket'
}
};
var req = http.request(options);
req.end();
agent.on('upgrade', function(res, socket, upgradeHead) {
console.log('got upgraded!');
socket.end();
process.exit(0);
});
});By default set to 5. Determines how many concurrent sockets the agent can have open.
An array of sockets currently in use by the Agent. Do not modify.
A queue of requests waiting to be sent to sockets.
This object is created internally and returned from http.request(). It
represents an in-progress request whose header has already been queued. The
header is still mutable using the setHeader(name, value), getHeader(name),
removeHeader(name) API. The actual header will be sent along with the first
data chunk or when closing the connection.
To get the response, add a listener for 'response' to the request object.
'response' will be emitted from the request object when the response
headers have been received. The 'response' event is executed with one
argument which is an instance of http.ClientResponse.
During the 'response' event, one can add listeners to the
response object; particularly to listen for the 'data' event. Note that
the 'response' event is called before any part of the response body is received,
so there is no need to worry about racing to catch the first part of the
body. As long as a listener for 'data' is added during the 'response'
event, the entire body will be caught.
// Good
request.on('response', function (response) {
response.on('data', function (chunk) {
console.log('BODY: ' + chunk);
});
});
// Bad - misses all or part of the body
request.on('response', function (response) {
setTimeout(function () {
response.on('data', function (chunk) {
console.log('BODY: ' + chunk);
});
}, 10);
});This is a Writable Stream.
This is an EventEmitter with the following events:
function () { }
Emitted when the server sends a '100 Continue' HTTP response, usually because the request contained 'Expect: 100-continue'. This is an instruction that the client should send the request body.
function (response) { }
Emitted when a response is received to this request. This event is emitted only once. The
response argument will be an instance of http.ClientResponse.
Sends a chunk of the body. By calling this method
many times, the user can stream a request body to a
server--in that case it is suggested to use the
['Transfer-Encoding', 'chunked'] header line when
creating the request.
The chunk argument should be an array of integers
or a string.
The encoding argument is optional and only
applies when chunk is a string.
Finishes sending the request. If any parts of the body are
unsent, it will flush them to the stream. If the request is
chunked, this will send the terminating '0\r\n\r\n'.
If data is specified, it is equivalent to calling request.write(data, encoding)
followed by request.end().
Aborts a request. (New since v0.3.8.)
This object is created when making a request with http.request(). It is
passed to the 'response' event of the request object.
The response implements the Readable Stream interface.
function (chunk) { }
Emitted when a piece of the message body is received.
function () { }
Emitted exactly once for each message. No arguments. After emitted no other events will be emitted on the response.
function (err) { }
Indicates that the underlaying connection was terminated before
end event was emitted.
See http.ServerRequest's 'close' event for more
information.
The 3-digit HTTP response status code. E.G. 404.
The HTTP version of the connected-to server. Probably either
'1.1' or '1.0'.
Also response.httpVersionMajor is the first integer and
response.httpVersionMinor is the second.
The response headers object.
The response trailers object. Only populated after the 'end' event.
Set the encoding for the response body. Either 'utf8', 'ascii', or 'base64'.
Defaults to null, which means that the 'data' event will emit a Buffer object..
Pauses response from emitting events. Useful to throttle back a download.
Resumes a paused response.
HTTPS is the HTTP protocol over TLS/SSL. In Node this is implemented as a separate module.
This class is a subclass of tls.Server and emits events same as
http.Server. See http.Server for more information.
Returns a new HTTPS web server object. The options is similer to
tls.createServer(). The requestListener is a function which is
automatically added to the 'request' event.
Example:
// curl -k https://localhost:8000/
var https = require('https');
var fs = require('fs');
var options = {
key: fs.readFileSync('test/fixtures/keys/agent2-key.pem'),
cert: fs.readFileSync('test/fixtures/keys/agent2-cert.pem')
};
https.createServer(options, function (req, res) {
res.writeHead(200);
res.end("hello world\n");
}).listen(8000);Makes a request to a secure web server.
Similar options to http.request().
Example:
var https = require('https');
var options = {
host: 'encrypted.google.com',
port: 443,
path: '/',
method: 'GET'
};
var req = https.request(options, function(res) {
console.log("statusCode: ", res.statusCode);
console.log("headers: ", res.headers);
res.on('data', function(d) {
process.stdout.write(d);
});
});
req.end();
req.on('error', function(e) {
console.error(e);
});The options argument has the following options
'localhost'.'/'.'GET'.null.null.Like http.get() but for HTTPS.
Example:
var https = require('https');
https.get({ host: 'encrypted.google.com', path: '/' }, function(res) {
console.log("statusCode: ", res.statusCode);
console.log("headers: ", res.headers);
res.on('data', function(d) {
process.stdout.write(d);
});
}).on('error', function(e) {
console.error(e);
});This module has utilities for URL resolution and parsing.
Call require('url') to use it.
Parsed URL objects have some or all of the following fields, depending on whether or not they exist in the URL string. Any parts that are not in the URL string will not be in the parsed object. Examples are shown for the URL
'http://user:[email protected]:8080/p/a/t/h?query=string#hash'
href: The full URL that was originally parsed.
Example: 'http://user:[email protected]:8080/p/a/t/h?query=string#hash'
protocol: The request protocol.
Example: 'http:'
host: The full host portion of the URL, including port and authentication information.
Example: 'user:[email protected]:8080'
auth: The authentication information portion of a URL.
Example: 'user:pass'
hostname: Just the hostname portion of the host.
Example: 'host.com'
port: The port number portion of the host.
Example: '8080'
pathname: The path section of the URL, that comes after the host and before the query, including the initial slash if present.
Example: '/p/a/t/h'
search: The 'query string' portion of the URL, including the leading question mark.
Example: '?query=string'
query: Either the 'params' portion of the query string, or a querystring-parsed object.
Example: 'query=string' or {'query':'string'}
hash: The 'fragment' portion of the URL including the pound-sign.
Example: '#hash'
The following methods are provided by the URL module:
Take a URL string, and return an object. Pass true as the second argument to also parse
the query string using the querystring module.
Take a parsed URL object, and return a formatted URL string.
Take a base URL, and a href URL, and resolve them as a browser would for an anchor tag.
This module provides utilities for dealing with query strings. It provides the following methods:
Serialize an object to a query string. Optionally override the default separator and assignment characters.
Example:
querystring.stringify({foo: 'bar'})
// returns
'foo=bar'
querystring.stringify({foo: 'bar', baz: 'bob'}, ';', ':')
// returns
'foo:bar;baz:bob'Deserialize a query string to an object. Optionally override the default separator and assignment characters.
Example:
querystring.parse('a=b&b=c')
// returns
{ a: 'b', b: 'c' }The escape function used by querystring.stringify,
provided so that it could be overridden if necessary.
The unescape function used by querystring.parse,
provided so that it could be overridden if necessary.
A Read-Eval-Print-Loop (REPL) is available both as a standalone program and easily includable in other programs. REPL provides a way to interactively run JavaScript and see the results. It can be used for debugging, testing, or just trying things out.
By executing node without any arguments from the command-line you will be
dropped into the REPL. It has simplistic emacs line-editing.
mjr:~$ node
Type '.help' for options.
> a = [ 1, 2, 3];
[ 1, 2, 3 ]
> a.forEach(function (v) {
... console.log(v);
... });
1
2
3For advanced line-editors, start node with the environmental variable NODE_NO_READLINE=1.
This will start the REPL in canonical terminal settings which will allow you to use with rlwrap.
For example, you could add this to your bashrc file:
alias node="env NODE_NO_READLINE=1 rlwrap node"Starts a REPL with prompt as the prompt and stream for all I/O. prompt
is optional and defaults to > . stream is optional and defaults to
process.stdin.
Multiple REPLs may be started against the same running instance of node. Each will share the same global object but will have unique I/O.
Here is an example that starts a REPL on stdin, a Unix socket, and a TCP socket:
var net = require("net"),
repl = require("repl");
connections = 0;
repl.start("node via stdin> ");
net.createServer(function (socket) {
connections += 1;
repl.start("node via Unix socket> ", socket);
}).listen("/tmp/node-repl-sock");
net.createServer(function (socket) {
connections += 1;
repl.start("node via TCP socket> ", socket);
}).listen(5001);Running this program from the command line will start a REPL on stdin. Other
REPL clients may connect through the Unix socket or TCP socket. telnet is useful
for connecting to TCP sockets, and socat can be used to connect to both Unix and
TCP sockets.
By starting a REPL from a Unix socket-based server instead of stdin, you can connect to a long-running node process without restarting it.
Inside the REPL, Control+D will exit. Multi-line expressions can be input.
The special variable _ (underscore) contains the result of the last expression.
> [ "a", "b", "c" ]
[ 'a', 'b', 'c' ]
> _.length
3
> _ += 1
4The REPL provides access to any variables in the global scope. You can expose a variable
to the REPL explicitly by assigning it to the context object associated with each
REPLServer. For example:
// repl_test.js
var repl = require("repl"),
msg = "message";
repl.start().context.m = msg;Things in the context object appear as local within the REPL:
mjr:~$ node repl_test.js
> m
'message'There are a few special REPL commands:
.break - While inputting a multi-line expression, sometimes you get lost
or just don't care about completing it. .break will start over..clear - Resets the context object to an empty object and clears any multi-line expression..exit - Close the I/O stream, which will cause the REPL to exit..help - Show this list of special commands.You can access this module with:
var vm = require('vm');JavaScript code can be compiled and run immediately or compiled, saved, and run later.
vm.runInThisContext() compiles code as if it were loaded from filename,
runs it and returns the result. Running code does not have access to local scope. filename is optional.
Example of using vm.runInThisContext and eval to run the same code:
var localVar = 123,
usingscript, evaled,
vm = require('vm');
usingscript = vm.runInThisContext('localVar = 1;',
'myfile.vm');
console.log('localVar: ' + localVar + ', usingscript: ' +
usingscript);
evaled = eval('localVar = 1;');
console.log('localVar: ' + localVar + ', evaled: ' +
evaled);
// localVar: 123, usingscript: 1
// localVar: 1, evaled: 1vm.runInThisContext does not have access to the local scope, so localVar is unchanged.
eval does have access to the local scope, so localVar is changed.
In case of syntax error in code, vm.runInThisContext emits the syntax error to stderr
and throws an exception.
vm.runInNewContext compiles code to run in sandbox as if it were loaded from filename,
then runs it and returns the result. Running code does not have access to local scope and
the object sandbox will be used as the global object for code.
sandbox and filename are optional.
Example: compile and execute code that increments a global variable and sets a new one. These globals are contained in the sandbox.
var util = require('util'),
vm = require('vm'),
sandbox = {
animal: 'cat',
count: 2
};
vm.runInNewContext('count += 1; name = "kitty"', sandbox, 'myfile.vm');
console.log(util.inspect(sandbox));
// { animal: 'cat', count: 3, name: 'kitty' }Note that running untrusted code is a tricky business requiring great care. To prevent accidental
global variable leakage, vm.runInNewContext is quite useful, but safely running untrusted code
requires a separate process.
In case of syntax error in code, vm.runInNewContext emits the syntax error to stderr
and throws an exception.
createScript compiles code as if it were loaded from filename,
but does not run it. Instead, it returns a vm.Script object representing this compiled code.
This script can be run later many times using methods below.
The returned script is not bound to any global object.
It is bound before each run, just for that run. filename is optional.
In case of syntax error in code, createScript prints the syntax error to stderr
and throws an exception.
Similar to vm.runInThisContext but a method of a precompiled Script object.
script.runInThisContext runs the code of script and returns the result.
Running code does not have access to local scope, but does have access to the global object
(v8: in actual context).
Example of using script.runInThisContext to compile code once and run it multiple times:
var vm = require('vm');
globalVar = 0;
var script = vm.createScript('globalVar += 1', 'myfile.vm');
for (var i = 0; i < 1000 ; i += 1) {
script.runInThisContext();
}
console.log(globalVar);
// 1000Similar to vm.runInNewContext a method of a precompiled Script object.
script.runInNewContext runs the code of script with sandbox as the global object and returns the result.
Running code does not have access to local scope. sandbox is optional.
Example: compile code that increments a global variable and sets one, then execute this code multiple times. These globals are contained in the sandbox.
var util = require('util'),
vm = require('vm'),
sandbox = {
animal: 'cat',
count: 2
};
var script = vm.createScript('count += 1; name = "kitty"', 'myfile.vm');
for (var i = 0; i < 10 ; i += 1) {
script.runInNewContext(sandbox);
}
console.log(util.inspect(sandbox));
// { animal: 'cat', count: 12, name: 'kitty' }Note that running untrusted code is a tricky business requiring great care. To prevent accidental
global variable leakage, script.runInNewContext is quite useful, but safely running untrusted code
requires a separate process.
Node provides a tri-directional popen(3) facility through the ChildProcess
class.
It is possible to stream data through the child's stdin, stdout, and
stderr in a fully non-blocking way.
To create a child process use require('child_process').spawn().
Child processes always have three streams associated with them. child.stdin,
child.stdout, and child.stderr.
ChildProcess is an EventEmitter.
function (code, signal) {}
This event is emitted after the child process ends. If the process terminated
normally, code is the final exit code of the process, otherwise null. If
the process terminated due to receipt of a signal, signal is the string name
of the signal, otherwise null.
See waitpid(2).
A Writable Stream that represents the child process's stdin.
Closing this stream via end() often causes the child process to terminate.
A Readable Stream that represents the child process's stdout.
A Readable Stream that represents the child process's stderr.
The PID of the child process.
Example:
var spawn = require('child_process').spawn,
grep = spawn('grep', ['ssh']);
console.log('Spawned child pid: ' + grep.pid);
grep.stdin.end();Launches a new process with the given command, with command line arguments in args.
If omitted, args defaults to an empty Array.
The third argument is used to specify additional options, which defaults to:
{ cwd: undefined,
env: process.env,
customFds: [-1, -1, -1],
setsid: false
}cwd allows you to specify the working directory from which the process is spawned.
Use env to specify environment variables that will be visible to the new process.
With customFds it is possible to hook up the new process' [stdin, stdout, stderr] to
existing streams; -1 means that a new stream should be created. setsid,
if set true, will cause the subprocess to be run in a new session.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
var util = require('util'),
spawn = require('child_process').spawn,
ls = spawn('ls', ['-lh', '/usr']);
ls.stdout.on('data', function (data) {
console.log('stdout: ' + data);
});
ls.stderr.on('data', function (data) {
console.log('stderr: ' + data);
});
ls.on('exit', function (code) {
console.log('child process exited with code ' + code);
});Example: A very elaborate way to run 'ps ax | grep ssh'
var util = require('util'),
spawn = require('child_process').spawn,
ps = spawn('ps', ['ax']),
grep = spawn('grep', ['ssh']);
ps.stdout.on('data', function (data) {
grep.stdin.write(data);
});
ps.stderr.on('data', function (data) {
console.log('ps stderr: ' + data);
});
ps.on('exit', function (code) {
if (code !== 0) {
console.log('ps process exited with code ' + code);
}
grep.stdin.end();
});
grep.stdout.on('data', function (data) {
console.log(data);
});
grep.stderr.on('data', function (data) {
console.log('grep stderr: ' + data);
});
grep.on('exit', function (code) {
if (code !== 0) {
console.log('grep process exited with code ' + code);
}
});Example of checking for failed exec:
var spawn = require('child_process').spawn,
child = spawn('bad_command');
child.stderr.setEncoding('utf8');
child.stderr.on('data', function (data) {
if (/^execvp\(\)/.test(data)) {
console.log('Failed to start child process.');
}
});See also: child_process.exec()
High-level way to execute a command as a child process, buffer the output, and return it all in a callback.
var util = require('util'),
exec = require('child_process').exec,
child;
child = exec('cat *.js bad_file | wc -l',
function (error, stdout, stderr) {
console.log('stdout: ' + stdout);
console.log('stderr: ' + stderr);
if (error !== null) {
console.log('exec error: ' + error);
}
});The callback gets the arguments (error, stdout, stderr). On success, error
will be null. On error, error will be an instance of Error and err.code
will be the exit code of the child process, and err.signal will be set to the
signal that terminated the process.
There is a second optional argument to specify several options. The default options are
{ encoding: 'utf8',
timeout: 0,
maxBuffer: 200*1024,
killSignal: 'SIGTERM',
cwd: null,
env: null }If timeout is greater than 0, then it will kill the child process
if it runs longer than timeout milliseconds. The child process is killed with
killSignal (default: 'SIGTERM'). maxBuffer specifies the largest
amount of data allowed on stdout or stderr - if this value is exceeded then
the child process is killed.
Send a signal to the child process. If no argument is given, the process will
be sent 'SIGTERM'. See signal(7) for a list of available signals.
var spawn = require('child_process').spawn,
grep = spawn('grep', ['ssh']);
grep.on('exit', function (code, signal) {
console.log('child process terminated due to receipt of signal '+signal);
});
// send SIGHUP to process
grep.kill('SIGHUP');Note that while the function is called kill, the signal delivered to the child
process may not actually kill it. kill really just sends a signal to a process.
See kill(2)
This module is used for writing unit tests for your applications, you can
access it with require('assert').
Throws an exception that displays the values for actual and expected separated by the provided operator.
Tests if value is a true value, it is equivalent to assert.equal(true, value, message);
Tests shallow, coercive equality with the equal comparison operator ( == ).
Tests shallow, coercive non-equality with the not equal comparison operator ( != ).
Tests for deep equality.
Tests for any deep inequality.
Tests strict equality, as determined by the strict equality operator ( === )
Tests strict non-equality, as determined by the strict not equal operator ( !== )
Expects block to throw an error. error can be constructor, regexp or
validation function.
Validate instanceof using constructor:
assert.throws(
function() {
throw new Error("Wrong value");
},
Error
);Validate error message using RegExp:
assert.throws(
function() {
throw new Error("Wrong value");
},
/value/
);Custom error validation:
assert.throws(
function() {
throw new Error("Wrong value");
},
function(err) {
if ( (err instanceof Error) && /value/.test(err) ) {
return true;
}
},
"unexpected error"
);Expects block not to throw an error, see assert.throws for details.
Tests if value is not a false value, throws if it is a true value. Useful when
testing the first argument, error in callbacks.
Use require('tty') to access this module.
Example:
var tty = require('tty');
tty.setRawMode(true);
process.stdin.resume();
process.stdin.on('keypress', function(char, key) {
if (key && key.ctrl && key.name == 'c') {
console.log('graceful exit');
process.exit()
}
});Spawns a new process with the executable pointed to by path as the session
leader to a new pseudo terminal.
Returns an array [slaveFD, childProcess]. slaveFD is the file descriptor
of the slave end of the pseudo terminal. childProcess is a child process
object.
Returns true or false depending on if the fd is associated with a
terminal.
mode should be true or false. This sets the properties of the current
process's stdin fd to act either as a raw device or default.
ioctls the window size settings to the file descriptor.
Returns [row, col] for the TTY associated with the file descriptor.
Use require('os') to access this module.
Returns the hostname of the operating system.
Returns the operating system name.
Returns the operating system release.
Returns the system uptime in seconds.
Returns an array containing the 1, 5, and 15 minute load averages.
Returns the total amount of system memory in bytes.
Returns the amount of free system memory in bytes.
Returns an array of objects containing information about each CPU/core installed: model, speed (in MHz), and times (an object containing the number of CPU ticks spent in: user, nice, sys, idle, and irq).
Example inspection of os.cpus:
[ { model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 252020,
nice: 0,
sys: 30340,
idle: 1070356870,
irq: 0 } },
{ model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 306960,
nice: 0,
sys: 26980,
idle: 1071569080,
irq: 0 } },
{ model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 248450,
nice: 0,
sys: 21750,
idle: 1070919370,
irq: 0 } },
{ model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 256880,
nice: 0,
sys: 19430,
idle: 1070905480,
irq: 20 } },
{ model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 511580,
nice: 20,
sys: 40900,
idle: 1070842510,
irq: 0 } },
{ model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 291660,
nice: 0,
sys: 34360,
idle: 1070888000,
irq: 10 } },
{ model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 308260,
nice: 0,
sys: 55410,
idle: 1071129970,
irq: 880 } },
{ model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times:
{ user: 266450,
nice: 1480,
sys: 34920,
idle: 1072572010,
irq: 30 } } ]V8 comes with an extensive debugger which is accessible out-of-process via a
simple TCP protocol.
Node has a built-in client for this debugger. To use this, start Node with the
debug argument; a prompt will appear:
% node debug myscript.js
debug>At this point myscript.js is not yet running. To start the script, enter
the command run. If everything works okay, the output should look like
this:
% node debug myscript.js
debug> run
debugger listening on port 5858
connecting...okNode's debugger client doesn't support the full range of commands, but
simple step and inspection is possible. By putting the statement debugger;
into the source code of your script, you will enable a breakpoint.
For example, suppose myscript.js looked like this:
// myscript.js
x = 5;
setTimeout(function () {
debugger;
console.log("world");
}, 1000);
console.log("hello");Then once the debugger is run, it will break on line 4.
% ./node debug myscript.js
debug> run
debugger listening on port 5858
connecting...ok
hello
break in #<an Object>._onTimeout(), myscript.js:4
debugger;
^
debug> next
break in #<an Object>._onTimeout(), myscript.js:5
console.log("world");
^
debug> print x
5
debug> print 2+2
4
debug> next
world
break in #<an Object>._onTimeout() returning undefined, myscript.js:6
}, 1000);
^
debug> quit
A debugging session is active. Quit anyway? (y or n) y
%The print command allows you to evaluate variables. The next command steps
over to the next line. There are a few other commands available and more to
come type help to see others.
The V8 debugger can be enabled and accessed either by starting Node with
the --debug command-line flag or by signaling an existing Node process
with SIGUSR1.
There are many third party modules for Node. At the time of writing, August 2010, the master repository of modules is the wiki page.
This appendix is intended as a SMALL guide to new-comers to help them quickly find what are considered to be quality modules. It is not intended to be a complete list. There may be better more complete modules found elsewhere.
Module Installer: npm
HTTP Middleware: Connect
Web Framework: Express
Web Sockets: Socket.IO
HTML Parsing: HTML5
Serialization: msgpack
Scraping: Apricot
Debugger: ndb is a CLI debugger inspector is a web based tool.
Testing/TDD/BDD: vows, expresso, mjsunit.runner
Patches to this list are welcome.