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Javascript String - replace() Method


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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:

PatternInserts
$$ Inserts a "$".
$&Inserts the matched substring.
$` Inserts the portion of the string that precedes the matched substring.
$'Inserts the portion of the string that follows the matched substring.
$n or $nnWhere n or nn are decimal digits, inserts the nth parenthesized submatch string, provided the first argument was a RegExp object.

Syntax:

string.replace(regexp/substr, newSubStr/function[, flags]);

Here is the detail of 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.

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>
<script type="text/javascript">

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>

To understand it in better way you can Try it yourself.

Example:

Following example shows how to switch words in a string:

<html>
<head>
<title>JavaScript String replace() Method</title>
</head>
<body>
<script type="text/javascript">

var re = /(\w+)\s(\w+)/;
var str = "zara ali";
var newstr = str.replace(re, "$2, $1");
document.write(newstr);

</script>
</body>
</html>

To understand it in better way you can Try it yourself.



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