Professional JavaScript

Array Properties

Accessed as	After Call 1	After Call 2	Notes
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?
reg.global	true	true	Has the 'g' switch been used?
reg.source	(\d{2}2)	(\d{2}2)	The pattern being matched

Static Regular Expression Properties

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	652	122	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

• It does not support the 'run-on' style of operation when the global flag is set.
• JScript regular expressions only have five properties as follows

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.