实现一个 Function.bind

Function.prototype.bind2 = function(context) {
  if (typeof this !== "function") {
    throw new Error(
      "Function.prototype.bind - what is trying to be bound is not callable"
    );
  }
  var self = this;
  var args = Array.prototype.slice.call(arguments, 1);
  var fNOP = function() {};
  var fbound = function() {
    self.apply(
      this instanceof self ? this : context,
      args.concat(Array.prototype.slice.call(arguments))
    );
  };
  fNOP.prototype = this.prototype;
  fbound.prototype = new fNOP();
  return fbound;
};