/**
 * This library adds several new properties to the javascript String object.
 */

/**
 * Checks where the current string ends with the specified sub-string or not.
 */
String.prototype.endsWith = function(s) {
	var reg = new RegExp(s + "$");
	return reg.test(this);
}

/**
 * Checks where the current string starts with the specified sub-string or not.
 */
String.prototype.startsWith = function(s) {
	var reg = new RegExp("^" + s);
	return reg.test(this);
}

/**
 * Only numbers are permitted.
 */
function checkIt(str) {
	return isNaN(str);
}