ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Using regular expressions
The x (extended) flag
Regular expressions can be difficult to read, especially when they include a lot of metasymbols and metasequences. For
example:
/|(\s*[^>]*>)).*?/gi
When you use the x (extended) flag in a regular expression, any blank spaces that you type in the pattern are ignored.
For example, the following regular expression is identical to the previous example:
/ |
(\s*
[^>]*
>)) .*? /gix
If you have the x flag set and do want to match a blank space character, precede the blank space with a backslash. For
example, the following two regular expressions are equivalent:
/foo bar/
/foo \ bar/x
The lastIndex property
The lastIndex property specifies the index position in the string at which to start the next search. This property
affects the exec() and test() methods called on a regular expression that has the g flag set to true. For example,
consider the following code:
var pattern:RegExp = /p\w*/gi;
var str:String = "Pedro Piper picked a peck of pickled peppers.";
trace(pattern.lastIndex);
var result:Object = pattern.exec(str);
while (result != null)
{
trace(pattern.lastIndex);
result = pattern.exec(str);
}
The lastIndex property is set to 0 by default (to start searches at the beginning of the string). After each match, it is
set to the index position following the match. Therefore, the output for the preceding code is the following:
0
5
11
18
25
36
44
If the global flag is set to false, the exec() and test() methods do not use or set the lastIndex property.
The match(), replace(), and search() methods of the String class start all searches from the beginning of the string,
regardless of the setting of the lastIndex property of the regular expression used in the call to the method. (However,
the match() method does set lastIndex to 0.)
You can set the lastIndex property to adjust the starting position in the string for regular expression matching.
The source property
The source property specifies the string that defines the pattern portion of a regular expression. For example:
var pattern:RegExp = /foo/gi;
trace(pattern.source); // foo
Last updated 6/6/2012
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