Drus’ blog, my stuff.

String.prototype.isEmail = function() {
	if (!this) {
		return false;
	}
	var iChars = "*|,\":<>[]{}`';()&$#% ";
	for (var i = 0; i<this.length; i++) {
		if (iChars.indexOf(this.charAt(i)) != -1) {
			return false;
		}
	}
	if (this.indexOf("@") == -1) {
		return false;
	}
	if (this.indexOf(".") == -1) {
		return false;
	}
	return true;
};
//Uso:
mail="jaja@pua.es";
trace(mail.isEmail());