SOURCE

var foo = {
  value :1
}
function bar(name){
  console.log('......')
  console.log(name)
  this.b = '22';
  console.log(this.value)
}
// bar.bind(foo)()
//1.
// Function.prototype.bind2 = function(context){
//   var self = this;
//   return function(){
//     self.apply(context)
//   }
// }
//2.增加参数
// Function.prototype.bind2 = function(context){
//   var self = this;

//   var args = Array.prototype.slice.call(arguments,1)
//   return function(){
//     var argsBind = Array.prototype.slice.call(arguments)
//     self.apply(context,args.concat(argsBind))
//   }
// }
//3.构造函数
var value =3
bar.prototype.a = 'wgf'
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 fnull = function(){}
  var args = Array.prototype.slice.call(arguments,1)
  var fn =  function(){
    var argsBind = Array.prototype.slice.call(arguments)
    self.apply(this instanceof self?this :context,args.concat(argsBind))
  }
  fnull.prototype = this.prototype;
  fn.prototype = new fnull();
  return fn
}

var obj =   bar.bind2(a);
// var obj1 = new obj('ccc');
// console.log(obj1.b)