Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All

index Property

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

{RegExp | reArray}.index

RegExp

Required. The global RegExp object.

reArray

Required. An array returned by the exec method of a Regular Expression object.

The index property is zero-based.

The initial value of the RegExp.index property is –1. Its value is read-only and changes whenever a successful match is made.

NoteNote

The properties of the RegExp object are not available when a program is running in fast mode, the default for JScript. To compile a program that uses these properties from a command prompt, you must turn off the fast option by using /fast-. It is not safe to turn off the fast option in ASP.NET because of threading issues.

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

var src = "The quick brown fox jumps over the lazy dog.";

// Create regular expression pattern with a global flag.
var re = /\w+/g;

// Get the next word, starting at the position of lastIndex.
var arr;
while ((arr = re.exec(src)) != null)
    {
    print (arr.index + "-" + arr.lastIndex + " " + arr);
    }

The output of this program is as follows.

0-3 The
4-9 quick
10-15 brown
16-19 fox
20-25 jumps
26-30 over
31-34 the
35-39 lazy
40-43 dog

Community Additions

ADD
Show:
© 2015 Microsoft