Professional JavaScript | 15 | WebReference

Professional JavaScript | 15


Professional JavaScript

Array Properties

Accessed asAfter Call 1After Call 2Notes
results.index 1 4 Character position at which match occurred
results.input 965212234 965212234 The target string

Pattern Properties

Accessed as After Call 1 After Call 2 Notes
reg.lastIndex 4 7 The index from which to begin the next search
reg.ignoreCase false false Has the 'i' switch been used? true true Has the 'g' switch been used?
reg.source (\d{2}2) (\d{2}2) The pattern being matched

Static Regular Expression Properties

Always referred to as properties of the generic RegExp object

Accessed as After Call 1 After Call 2 Notes
RegExp. lastMatch 652 122 Last character sequence to match the pattern
RegExp. leftContext 9 9652 Characters to the left of the matching sequence
RegExp. rightContext 12234 34 Characters to the right of the matching sequence
RegExp.$1 652122 See previous explanation
RegExp. LastParen 652 122 The last substring match to a parenthesized subexpression.

As you can see, exec() does a lot of behind the scenes work, especially if you're running Navigator.

Limitations of exec() in Internet Explorer

The JScript version of exec() is quite limited in comparison to that in JavaScript in two ways:

RegExp.index, RegExp.input : Equivalent to results.index and results.input as above.

RegExp.lastIndex, reg.source: Equivalent to reg.lastIndex and reg.source as above

RegExp.$1: Equivalent to RegExp.$1 as above.

And so, with all that information behind us, we conclude our tour of regular expression support in JavaScript.

Created: February 21, 2001
Revised: February 26, 2001