String.prototype.trim = function() { return (this.replace(/^(\s*)/, "").replace(/(\s*$)/, "")); };
String.prototype.isEmpty = function() { return (this == null || this.trim() == "") };
String.prototype.isMail = function() { return (/^[a-zA-Z0-9]{1}[\w\.\-]{2,63}@[a-zA-Z0-9]{1}[\w\.\-]{2,63}\.[a-zA-Z]{2,4}$/).test(this); };