手写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 && oThis ? this : oThis || window,
              aArgs.concat(Array.prototype.slice.call(arguments))
          );
        };
  
    fNOP.prototype = this.prototype;
    fBound.prototype = new fNOP();

    return fBound;
  };