Learning JavaScript's Bind | MDN's Implementation

mdn_bind.js

if (!Function.prototype.bind) {
  Function.prototype.bind = function (oThis) {
    if (typeof this !== "function") {
      throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable");
    }

    var aArgs = Array.prototype.slice.call(arguments, 1),
      fToBind = this,
      fNOP = function () {},
      fBound = function () {
        return fToBind.apply(this instanceof fNOP 
          ? this 
          : oThis || window
          , aArgs.concat(Array.prototype.slice.call(arguments))
        ); 
      };
    fNOP.prototype = this.prototype;
    fBound.prototype = new fNOP();

    return fBound;
  };
}