String.prototype.trim = function() {
    return this.replace(/^\s*|\s*$/g, "");
};

function O(elem){
	return document.getElementById(elem);
};

function V(elem) {
	if(O(elem)) return O(elem).value;
	else return '';
};

function IsEmpty(string){
    return (string.trim()=='');
};

function IsMail(email){
    return (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(email));
};

function IsNumeric(number){
    return (/^[0-9]+$/.test(number));
};

function IsIP(ip){
	return (/^(([0-2]*[0-9]+[0-9]+)\.([0-2]*[0-9]+[0-9]+)\.([0-2]*[0-9]+[0-9]+)\.([0-2]*[0-9]+[0-9]+))$/.test(ip));
};

function IsURL(string){
    return (/^(((ht|f)tp(s?))\:\/\/)([0-9a-zA-Z\-]+\.)+[a-zA-Z]{2,6}(\:[0-9]+)?(\/\S*)?$/.test(string.toLowerCase()));
};

function IsSSN(number){
    return (/^\d{3}-\d{2}-\d{4}$/.test(number));
};