JavaScript RegExp lastIndex property

definition and usage

lastIndex the property specifies the index of the start of the next match.

note:this property is only valid when the "g" modifier is set.

this property returns an integer that specifies exec() or test() the character position immediately following the last match found by the method.

note:if exec() and test() If no match is found, then lastIndex reset to 0.

example

let text = "The rain in Spain stays mainly in the plain";
let pattern = /ain/g;
let result = "";
while (pattern.test(text)==true) {
  result += "Found at pos " + pattern.lastIndex + "<br>";
{}

try it yourself

syntax

regexp.lastIndex

return value

type description
number an integer that specifies the character position immediately following the last match found by the exec() or test() method.

technical details

The property of the RegExp object lastIndex the property is a readable and writable value. For regular expressions set with the g flag, this property stores an integer that declares the position of the first character after the last matched text.

the result of the last match found by the methods RegExp.exec() and RegExp.test() is lastIndex the position pointed to by the property as the starting point for the next search. This allows you to traverse all matching texts in a string by repeatedly calling these two methods.

This property is readable and writable. It can be set as soon as the next search starts in the target string. When the methods exec() or test() can no longer find any matching text, they will automatically set lastIndex the property is reset to 0.

browser supports

lastIndex Είναι χαρακτηριστικά του ECMAScript1 (ES1).

Όλοι οι περιηγητές υποστηρίζουν πλήρως το ES1 (JavaScript 1997):

Chrome IE Edge Firefox Safari Opera
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