Javascript String regex

/**// w w w .  j  a v a2s .  c  om
@Name: String.prototype.regex
@Description: Used to match strings to common patterns
@Example:
alert('01/22/1977'.match(String.prototype.regex('mm/dd/yyyy'));
*/
String.prototype.regex = {
 'mm/dd/yyyy' : new RegExp(/^\d{2}\/\d{2}\/\d{4}$/),
 'mm/dd/yy' : new RegExp(/^\d{2}\/\d{2}\/\d{2}$/),
 'phone_with_area' : new RegExp(/^\d{3}-\d{3}-\d{4}$/),
 'social_security' : new RegExp(/^\d{3}-\d{2}-\d{4}$/),
 'zip5' : new RegExp(/^\d{5}$/),
 'zip9' : new RegExp(/^\d{5}-\d{4}$/)
};

String.prototype.regex = function() {
 // http://stackoverflow.com/questions/3446170
 return this.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
};

function byId (id) {
 return document.getElementById(id);
}