Easy startsWith/endsWith proto functions for the String object

JavaScript String StartsWith and EndsWith.js

if (typeof String.prototype.startsWith != 'function') {
	String.prototype.startsWith = function (str){
		return this.slice(0, str.length) == str;
	};
}
if (typeof String.prototype.endsWith != 'function') {
	String.prototype.endsWith = function (str){
		return this.slice(-str.length) == str;
	};
}

Source: http://stackoverflow.com/questions/646628/javascript-startswith