JavaScript 2.0-The Complete Reference, Second ... - freecodingtutorial

Table 8-6: Instance Properties of RegExp Objects
Property Value Example
multiline Boolean indicating whether
the multiline
flag (m) was set. This
property is ReadOnly.
source The string form of the
regular expression. This
property is ReadOnly.
var pattern = /(cat) (dog)/g;
pattern.test("this is a cat dog
and cat dog");
document.writeln(pattern.
multiline);
// prints false
var pattern = /(cat) (dog)/g;
pattern.test("this is a cat dog
and cat dog");
document.writeln(pattern.source);
// prints (cat) (dog)
The RegExp class object also has static properties that can be very useful. These properties
are listed in Table 8-7 and come in two forms. The alternate form uses a dollar sign and a
special character and may be recognized by those who are already intimately familiar with
regexps. A downside to the alternate form is that it has to be accessed in an associative array
fashion. Note that using this form will probably confuse those readers unfamiliar with languages
like Perl, so it is definitely best to just stay away from it.
Table 8-7: Static Properties of the RegExp Class Object
Property Alternat
e Form
>$1, $2, …,
$9
Value Example
>None >Strings
holding
the text of the
first
nine
parenthesized
subexpressio
ns
of the most
recent match.
>index >None >Holds the
string
index value of
the first
character in
the most
recent pattern
match. This
property is not
part of the
ECMA
standard,
though it
is supported
widely.
Therefore, it
>var pattern = /(cat) (dog)/g;
pattern.test("this is a cat dog
and cat dog");
document.writeln
("$1="
document.writeln
("$2="
// prints $1= cat $2 = dog
>var pattern = /(cat) (dog)/g;
pattern.test("this is a
cat dog and cat dog");
document.writeln
(RegExp.index);
// prints 10