Javascript - RegExp constructor argument


Regular expressions can be created via the RegExp constructor.

It accepts two arguments: a string pattern and an optional string of flags.

Any regular expression that can be defined using literal syntax can be defined using the constructor:

The following Regular expressions match the first instance of "bat" or "cat", regardless of case.

var pattern1 = /[bc]at/i;

Same as pattern1, using the constructor.

var pattern2 = new RegExp("[bc]at", "i");

Since the argument of the RegExp constructor is a string, you need to escape characters.

All metacharacters must be double-escaped, \\ becomes \\\\ when used in a regular-expression string.


var re = null,
    i;/* w ww . j a v  a2  s .c om*/

re = new RegExp("cat", "g");