isValidEmailAddress.js

/****

RFC822 Email Address Regex

Translated to Javascript by Renato Albano

http://tfletcher.com/lib/rfc822.rb
http://iamcal.com/publish/articles/php/parsing_email/

Licensed under a Creative Commons Attribution-ShareAlike 2.5 License
http://creativecommons.org/licenses/by-sa/2.5/
*****/ 

var isValidEmailAddress = function(email) {
	qtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';
	dtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';
	atom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-';
	atom += '\\x3c\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';
	quoted_pair = '\\x5c[\\x00-\\x7f]';
	domain_literal = "\\x5b(?:"+dtext+"|"+quoted_pair+")*\\x5d";
	quoted_string = "\\x22(?:"+qtext+"|"+quoted_pair+")*\\x22";
	domain_ref = atom;
	sub_domain = "(?:"+domain_ref+"|"+domain_literal+")";
	word = "(?:"+atom+"|"+quoted_string+")";
	domain = sub_domain+"(?:\\x2e"+sub_domain+")*";
	local_part = word+"(?:\\x2e"+word+")*";
	addr_spec = local_part+"\\x40"+domain;
	pattern = "^"+addr_spec+"$";
	
	return (new RegExp(pattern)).test(email);
}