Javascript Array select(selector, context)

Array.prototype.select = Array.prototype.map || function (selector, context) {
 context = context || window;/*from  w  ww  .  j a v a  2 s .c o  m*/
 var arr = [];
 var l = this.length;
 for (var i = 0; i < l; i++)
  arr.push(selector.call(context, this[i], i, this));
 return arr;
};