Javascript built in String Functions

Covered String Functions
• charAt()
• concat()
• indexOf()
• lastIndexOf()
• replace()
• search()
• substr()
• substring()
• toLowerCase()
• toUppserCase()

charAt()
Description:
• This method returns the character from the
specified index. Characters in a string are indexed
from left to right.
• The index of the first character is 0, and the index
of the last character in a string called string Name
is stringName.length - 1.
Syntax:
string.charAt(index);

charAt
Example
<html>
<head>
<title>JavaScript String charAt() Method</title>
</head>
<body>
<script type="text/JavaScript">
var str = new String( "This is string" );
document.writeln("str.charAt(0) is:" + str.charAt(0));
</script>
</body>
</html>
Output
str.charAt(0) is: T

concat()
Description:
• This method adds two or more strings and returns a new
single string.
Syntax:
string.concat(string2, string3[, ..., stringN]);
parameters:
string2...stringN : These are the strings to be concatenated.

concat()
Example:
<html>
<head>
<title>JavaScript String concat() Method</title>
</head>
<body>
<script type="text/javascript">
var str1 = new String( "This is string one" );
var str2 = new String( "This is string two" );
var str3 = str1.concat( str2 );
document.write("Concatenated String :" + str3);
</script>
</body></html>
Output:
Concatenated String :This is string oneThis is string two.

indexOf
Description:
• the first occurrence of the specified value, starting the
search at This method returns the index within the calling
String object of fromIndex or -1 if the value is not found.
Syntax:
string.indexOf(searchValue[, fromIndex])
Parameters:
searchValue : A string representing the value to search for.
fromIndex : The location within the calling string to start the
search from. It can be any integer between 0 and the length
of the string. The default value is 0.

indexOf
Example:
<html>
<head>
<title>JavaScript String indexOf() Method</title>
</head>
<body>
var str1 = new String( "This is string one" );
var index = str1.indexOf( "string" );
document.write("indexOf found String :" + index );
document.write("<br />");
var index = str1.indexOf( "one" );
document.write("indexOf found String :" + index );
</script>
</body></html>
Oputput:
indexOf found String :8
indexOf found String :15

lastIndexOf()
Description:
– This method returns the index within the calling String
object of the last occurrence of the specified value, starting
the search at fromIndex or -1 if the value is not found.
Syntax:
– string.lastIndexOf(searchValue[, fromIndex])
Parameters:
– searchValue : A string representing the value to search for.
– fromIndex : The location within the calling string to start the
search from. It can be any integer between 0 and the length
of the string. The default value is 0.
Return Value:
– . Returns the index of the last found occurrence otherwise -1
if not found

lastIndexOf()
Example:
<html>
<head>
<title>JavaScript String lastIndexOf() Method</title>
</head>
<body>
var str1 = new String( "This is string one and again string" );
var index = str1.lastIndexOf( "string" );
document.write("lastIndexOf found String :" + index );
document.write("<br />");
var index = str1.lastIndexOf( "one" );
document.write("lastIndexOf found String :" + index );
</script>
</body>
</html>
Output:
lastIndexOf found String :29
lastIndexOf found String :15

replace()
Description:
This method finds a match between a regular expression
and a string, and replaces the matched substring with a new
substring.
The replacement string can include the following special
replacement patterns:
Syntax:
string.replace(regexp/substr, newSubStr/function[, flags]);

replace()
Parameters:
– regexp : A RegExp object. The match is replaced by the
return value of parameter #2.
– substr : A String that is to be replaced by newSubStr.
– newSubStr : The String that replaces the substring received
from parameter #1.
– function : A function to be invoked to create the new
substring.
– flags : A String containing any combination of the RegExp
flags: g - global match, i - ignore case, m - match over
multiple lines. This parameter is only used if the first
parameter is a string.
Return Value:
– It simply returns a new changed string.

replace()
Example:
Following example shows how to use the global and ignore case flags
which permits replace to replace each occurrence of 'apples' in the string
with 'oranges'.
<html>
<head
<title>JavaScript String replace() Method</title>
</head>
<body>
var re = /apples/gi;
var str = "Apples are round, and apples are juicy.";
var newstr = str.replace(re, "oranges");
document.write(newstr );
</script>
</body>
</html>

search()
Description:
– This method Executes the search for a match between a
regular expression and this String object.
Syntax:
– string.search(regexp);
Parameters:
– regexp : A regular expression object. If a non-RegExp object
obj is passed, it is implicitly converted to a RegExp by using
new RegExp(obj)
Return Value:
– If successful, search returns the index of the regular
expression inside the string. Otherwise, it returns -1.

search()
Example:
<html>
<head>
<title>JavaScript String search() Method</title>
</head>
<body>
var re = /apples/gi;
if ( str.search(re) == -1 ){
document.write("Does not contain Apples" );
}else{
document.write("Contains Apples" );
}
</script>
</body>
</html>
Output:
Contains Apples

substr()
Description:
– This method returns the characters in a string beginning at
the specified location through the specified number of
characters.
Syntax:
– string.substr(start[, length]);
Parameters:
– start : Location at which to begin extracting characters (an
integer between 0 and one less than the length of the string).
– length : The number of characters to extract.
Note: If start is negative, substr uses it as a character index
from the end of the string.
Return Value:
– The substr method returns the new sub string based on
given parameters.

substr()
Example:
<html>
<head><title>JavaScript String substr() Method</title></head><body>
document.write("(1,2): " + str.substr(1,2));
document.write("<br />(-2,2): " + str.substr(-2,2));
document.write("<br />(1): " + str.substr(1));
document.write("<br />(-20, 2): " + str.substr(-20,2));
document.write("<br />(20, 2): " str.substr(20,2));
</script></body></html>
Output:
(1,2): pp
(-2,2): Ap
(1): pples are round, and apples are juicy.
(-20, 2): Ap
(20, 2): d

substring()
Description:
– This method returns a subset of a String object.
Syntax:
– string.substring(indexA, [indexB])
Parameters:
– indexA : An integer between 0 and one less than the length of
the string.
– indexB : (optional) An integer between 0 and the length of the
string.
Return Value:
– The substring method returns the new sub string based on
given parameters

substring()
Example:
<html>
<head><title>JavaScript String substring()
Method</title></head><body>
<script type=”text/javascript”>
var str = “Apples are round, and apples are juicy.”;
document.write( “(1,2): “ + str.substring(1,2));
document.write( “<br />(0,10):” + str.substring(0, 10));
document.write(“<br />(5): “ + str.substring(5));
</script></body> </html>
Output:
(1,2): p(0,10): Apples are (5): s are round, and apples are juicy.

toLowerCase()
Description:
– This method returns the calling string value
converted to lowercase.
Syntax:
– string.toLocaleLowerCase( )
Return Value:
– Returns the calling string value converted to
lowercase.

toLowerCase()
Example:
<html>
<head>
<title>JavaScript String toLowerCase() Method
</title></head><body>
var str = "Apples are round, and Apples are Juicy.";
document.write(str.toLowerCase( ));
</script></body> </html>
Output:
apples are round, and apples are juicy.

toUpperCase()
Description:
– This method returns the calling string value converted to
uppercase.
Syntax:
– string.toUpperCase( )
Return Value:
– Returns a string representing the specified object.

toUpperCase()
Example:
<html>
<head>
<title>JavaScript String toUpperCase() Method</title>
</head>
<body>
var str = "Apples are round, and Apples are Juicy.";
document.write(str.toUpperCase( ));
</script>
</body>
</html>
Output:
APPLES ARE ROUND, AND APPLES ARE JUICY.

Javascript built in String Functions

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