RegExp

You can create a regular expression object using the RegExp() constructor. You pass the expression pattern as the first parameter and the pattern modifiers as the second.

> var re = new RegExp('[dn]o+dle', 'gmi');

This matches "noodle", "doodle", "doooodle", and so on. It's equivalent to using the regular expression literal:

> var re = ('/[dn]o+dle/gmi'); // recommended

Chapter 4, Objects and Appendix D, Regular Expressions contains more information on regular expressions and patterns.

The RegExp.prototype members

Property/method	Description
global	Read-only. true if the g modifier was set when creating the regexp object.
ignoreCase	Read-only. true if the i modifier was set when creating the regexp object.
multiline	Read-only. true if the m modifier was set when creating the regexp object
lastIndex	Contains the position in the string where the next match should start. test() and exec() set this position after a successful match. Only relevant when the g (global) modifier was used. > var re = /[dn]o+dle/g; > re.lastIndex; 0 > re.exec("noodle doodle"); ["noodle"] > re.lastIndex; 6 > re.exec("noodle doodle"); ["doodle"] > re.lastIndex; 13 > re.exec("noodle doodle"); null > re.lastIndex; 0
source	Read-only. Returns the regular expression pattern (without the modifiers). > var re = /[nd]o+dle/gmi; > re.source; "[nd]o+dle"
exec(string)	Matches the input string with the regular expression. A successful match returns an array containing the match and any capturing groups. With the g modifier, it matches the first occurrence and sets the lastIndex property. Returns null when there's no match. > var re = /([dn])(o+)dle/g; > re.exec("noodle doodle"); ["noodle", "n", "oo"] > re.exec("noodle doodle"); ["doodle", "d", "oo"] The arrays returned by exec() have two additional properties: index (of the match) and input (the input string being searched).
test(string)	Same as exec() but only returns true or false. > /noo/.test('Noodle'); false > /noo/i.test('Noodle'); true