Java script

It is case sensitive language.
alert('hello');
Message
document.write('we are learning javascript');
Display

// Coments
Documentation/Comments
document.write('we are learning javascript');
Display

External File Support
1.Make new file
2.Write java code with ext js
3.Don’t need to write script tags in js files
4.<script scr = “ path of file ”>

DATA TYPES
String ‘shahwaiz’
Integer 6, 7, 9
Variable assign value, simple text
Space not allowed
name = ‘shahwaiz’;
document.write(name);

DATA TYPES
V1=3
V2=4
document.write(v1+v2);
alert(v1+v2);

USING HTML IN JAVA SCRIPT
Document.write(‘<h1>html</h1>in java script’);
Document.write(‘style=“background:red”java script’);

POP UP BOX
Prompt(‘Enter your name’,’name’);
name = Prompt(‘Enter your name’,’name’)
document.write(‘hello<h3>’+name+’</h3>welcome’);

MATH OPERATOR +
-
*
/
%
=
++
--

IF-ELSE var = 3
var2=4
if(var==3){
alert(‘Display’);
}
!== -> type
===

FUNCTION
Function myFunction()
{
document.write(‘this is function’);
}
myFunction();

JAVASCRIPT OBJECTS
Real Life Objects, Properties,
and Methods
A car has properties like weight
and color, and methods like start
and stop:
<!DOCTYPE html>
<html>
<body>
<p>Creating a JavaScript Variable.</p>
<p id="demo"></p>
<script>
var car = "Fiat";
document.getElementById("demo").innerHTML
= car;
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<body>
<p>Creating a JavaScript Object.</p>
<p id="demo"></p>
<script>
var car = {type:"Fiat", model:"500", color:"white"};
document.getElementById("demo").innerHTML = car.type;
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<body>
<p>Creating a JavaScript Object.</p>
<p id="demo"></p>
<script>
var person = {
firstName : "John",
lastName : "Doe",
age : 50,
eyeColor : "blue"
};
document.getElementById("demo").innerHTML =
person.firstName + " is " + person.age + " years old.";
</script>
</body>
</html>

ACCESSING OBJECT PROPERTIES
objectName.propertyName
Or
objectName["propertyName"]
p id="demo"></p>
<script>
var person = {
firstName: "John",
lastName : "Doe",
id : 5566
};
document.getElementById("demo").innerHTML
=
person.firstName + " " + person.lastName;
</script>

ACCESSING OBJECT METHODS
objectName.methodName()
or
name = person.fullName();
<p id="demo"></p>
<script>
var person = {
firstName: "John",
lastName : "Doe",
id : 5566,
fullName : function() {
return this.firstName + " " + this.lastName;
}
};
document.getElementById("demo").innerHTML =
person.fullName();
</script>

JAVASCRIPT EVENTS
• HTML events are "things" that happen to HTML elements.
• When JavaScript is used in HTML pages, JavaScript can "react" on these events.
• An HTML web page has finished loading
• An HTML input field was changed
• An HTML button was clicked

COMMON HTML EVENTS
onchange An HTML element has been changed
onclick The user clicks an HTML element
onmouseover The user moves the mouse over an HTML element
onmouseout The user moves the mouse away from an HTML element
onkeydown The user pushes a keyboard key
onload The browser has finished loading the page

SAMPLES
<button onclick="document.getElementById('demo').innerHTML = Date()">The time is?</button>
<button onclick="this.innerHTML = Date()">The time is?</button>
<button onclick="displayDate()">The time is?</button>

STRING
<script>
var txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
document.getElementById("demo").innerHTML = txt.length;
</script>

SPECIAL CHARACTERS
The backslash () escape character turns special characters into string characters:
' ' Single quote
" " Double quote
Backslash

SIX OTHER ESCAPE SEQUENCES ARE VALID IN
JAVASCRIPT:
b Backspace
f Form Feed
n New Line
r Carriage Return
t Horizontal Tabulator
v Vertical Tabulator

STR METHOD
The indexOf() method returns the index of (the position of)
the first occurrence of a specified text in a string:
var str = "Please locate where 'locate' occurs!";
var pos = str.indexOf("locate");

The lastIndexOf() method returns the index of
the last occurrence of a specified text in a string:
Both methods accept a second parameter as the starting
position for the search:
var str = "Please locate where 'locate' occurs!";
var pos = str.indexOf("locate",15);
The search() method searches a string for a specified value
and returns the position of the match:

EXTRACTING STRING PARTS
• slice(start, end)
• substring(start, end)
• substr(start, length)

REPLACING STRING CONTENT
str = "Please visit Microsoft!";
var n = str.replace("Microsoft", "W3Schools");
By default, the replace() function is case sensitive. Writing
MICROSOFT (with upper-case) will not work:
o replace case insensitive, use a regular expression with
an /i flag (insensitive):
str = "Please visit Microsoft!";
var n = str.replace(/MICROSOFT/i, "W3Schools");

To replace all matches, use a regular expression with a /g flag (global match):
str = "Please visit Microsoft and Microsoft!";
var n = str.replace(/Microsoft/g, "W3Schools");

JAVASCRIPT NUMBERS
JavaScript has only one type of number. Numbers can be written with or without decimals.
var x = 123e5; // 12300000
var y = 123e-5; // 0.00123
If you add two numbers, the result will be a number:
If you add two strings, the result will be a string concatenation:
If you add a number and a string, the result will be a string concatenation:
If you add a string and a number, the result will be a string concatenation:

NUMBER METHOD
var x = 123;
x.toString(); // returns 123 from variable x
(123).toString(); // returns 123 from literal 123
(100 + 23).toString(); // returns 123 from expression 100 + 23
var x = 9.656;
x.toExponential(2); // returns 9.66e+0

TOFIXED()
var x = 9.656;
x.toFixed(0); // returns 10
x.toFixed(2); // returns 9.66

TOPRECISION()
toPrecision() returns a string, with a number written with a specified length:
var x = 9.656;
x.toPrecision(); // returns 9.656
x.toPrecision(2); // returns 9.7

JAVASCRIPT MATH OBJECT
The JavaScript Math object allows you to perform mathematical tasks on
numbers.
Math.PI; // returns 3.141592653589793
Math.round(4.7); // returns 5
Math.round(4.4); // returns 4
Math.pow(8, 2); // returns 64
Math.sqrt(64); // returns 8
Math.abs(-4.7); // returns 4.7
Math.ceil(4.4); // returns 5
Math.floor(4.7); // returns 4

Math.sin(90 * Math.PI / 180); // returns 1 (the sine of 90 degrees)
Math.cos(0 * Math.PI / 180); // returns 1 (the cos of 0 degrees)
Math.min(0, 150, 30, 20, -8, -200); // returns -200
Math.random(); // returns a random number

Math.E // returns Euler's number
Math.PI // returns PI
Math.SQRT2 // returns the square root of 2
Math.SQRT1_2 // returns the square root of 1/2
Math.LN2 // returns the natural logarithm of 2
Math.LN10 // returns the natural logarithm of 10
Math.LOG2E // returns base 2 logarithm of E
Math.LOG10E // returns base 10 logarithm of E

JAVASCRIPT RANDOM
Math.floor(Math.random() * 10); // returns a number between 0 and 9

JAVASCRIPT DATES
var d = new Date();
document.getElementById("demo").innerHTML = d;
• Years
• Months
• Days
• Hours
• Seconds
• Milliseconds

• JavaScript can display the current date as a full string:
• Sun Apr 08 2018 23:28:32 GMT+0500 (Pakistan Standard Time)
There are 4 ways of initiating a date:
new Date()
new Date(milliseconds)
new Date(dateString)
new Date(year, month, day, hours, minutes, seconds, milliseconds)

JAVASCRIPT DATE INPUT
Type Example
ISO Date "2015-03-25" (The International Standard)
Short Date "03/25/2015"
Long Date "Mar 25 2015" or "25 Mar 2015"
Full Date "Wednesday March 25 2015"

JAVASCRIPT GET DATE METHODS
Method Description
getFullYear() Get the year as a four digit number (yyyy)
getMonth() Get the month as a number (0-11)
getDate() Get the day as a number (1-31)
getHours() Get the hour (0-23)
getMinutes() Get the minute (0-59)
getSeconds() Get the second (0-59)
getMilliseconds() Get the millisecond (0-999)
getTime() Get the time (milliseconds since January 1, 1970)
getDay() Get the weekday as a number (0-6)

JAVASCRIPT SET DATE METHODS
Method Description
setDate() Set the day as a number (1-31)
setFullYear() Set the year (optionally month and day)
setHours() Set the hour (0-23)
setMilliseconds() Set the milliseconds (0-999)
setMinutes() Set the minutes (0-59)
setMonth() Set the month (0-11)
setSeconds() Set the seconds (0-59)
setTime() Set the time (milliseconds since January 1, 1970)

JAVASCRIPT ARRAYS
JavaScript arrays are used to store multiple values in a single variable.
var cars = ["Saab", "Volvo", "BMW"];
var cars = new Array("Saab", "Volvo", "BMW");
cars[0] = "Opel";
document.getElementById("demo").innerHTML = cars[0];

ACCESS THE FULL ARRAY
document.getElementById("demo").innerHTML = cars;

REVERSING AN ARRAY
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.sort(); // Sorts the elements of fruits
fruits.reverse(); // Reverses the order of the elements

JAVASCRIPT TYPE CONVERSION
In JavaScript there are 5 different data types that can
contain values:
• string
• number
• boolean
• object
• function
There are 3 types of objects:
Object
Date
Array
And 2 data types that cannot contain values:
null
undefined

THE TYPEOF OPERATOR
typeof "John" // Returns "string"
typeof 3.14 // Returns "number"
typeof NaN // Returns "number"
typeof false // Returns "boolean"
typeof [1,2,3,4] // Returns "object"
typeof {name:'John', age:34} // Returns "object"
typeof new Date() // Returns "object"
typeof function () {} // Returns "function"
typeof myCar // Returns "undefined" *
typeof null // Returns "object“
The NaN (Not-a-Number) is a weirdo Global Object in javascript frequently
returned when some mathematical operation failed

JAVASCRIPT ERRORS - THROW AND TRY TO CATCH
• The try statement lets you test a block of code for errors.
• The catch statement lets you handle the error.
• The throw statement lets you create custom errors.
• The finally statement lets you execute code, after try and catch, regardless of the result.

Java script

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