lastIndex Property

Returns the character position where the next match begins in a searched string.


The object associated with this property is always the global RegExp object.


The lastIndex property is zero-based, that is, the index of the first character is zero. It's initial value is –1. Its value is modified whenever a successful match is made.

The lastIndex property is modified by the exec and test methods of the RegExp object, and the match, replace, and split methods of the String object.

The following rules apply to values of lastIndex:


The following example illustrates the use of the lastIndex property. This function iterates a search string and prints out the index and lastIndex values for each word in the string.

function RegExpTest(){
  var ver = Number(ScriptEngineMajorVersion() + "." + ScriptEngineMinorVersion())
  if (ver >= 5.5){
    var src = "The rain in Spain falls mainly in the plain.";
    var re = /\w+/g;
    var arr;
    while ((arr = re.exec(src)) != null)
       print(arr.index + "-" + arr.lastIndex + "\t" + arr);
    alert("You need a newer version of JScript for this to work");


Version 3

See Also

RegExp Object Properties | Regular Expression Syntax

Applies To: RegExp Object