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JavaScript lastIndex Property

< JavaScript RegExp Object

Example

Do a global search for "ain" in a string, and output the index after a match is found:

var str = "The rain in Spain stays mainly in the plain";
var patt1 = /ain/g;

while (patt1.test(str)==true)
  {
  document.write("'ain' found. Index now at: "+patt1.lastIndex);
  document.write("<br>");
  }

The output of the code above will be:

'ain' found. Index now at: 8
'ain' found. Index now at: 17
'ain' found. Index now at: 28
'ain' found. Index now at: 43
Try it Yourself »

Definition and Usage

The lastIndex property specifies the index at which to start the next match.

Note: This property only works if the "g" modifier is set.

This property returns an integer that specifies the character position immediately after the last match found by exec( ) or test( ) methods.

Note: exec( ) and test( ) reset lastIndex to 0 if they do not get a match.


Browser Support

Property
lastIndex Yes Yes Yes Yes Yes

Syntax

RegExpObject.lastIndex

Return Value

Type Description
Number An integer that specifies the character position immediately after the last match found by exec( ) or test( ) methods

Technical Details

JavaScript Version: 1.2

< JavaScript RegExp Object