JavaScript String - replace() Method

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 −

Pattern	Inserts
$$	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 $nn	Where n or nn are decimal digits, inserts the nth parenthesized submatch string, provided the first argument was a RegExp object.

Syntax

The syntax to use the replace() method is as follows −

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

Argument Details

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

Try the following example.

<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>

Output

oranges are round, and oranges are juicy.

Example

Try the following example; it 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>

Output

ali, zara