Function.prototype.bind

Function.prototype.bind = function () {

    var fn = this ;

    var context = [].shilft.call(arguments);

    var args= [].slice.call(arguments);

     return function () {

         return fn.apply(context, [].concat.call(args, [].slice.call(arguments));

     };

}

var foo = {

     x: 3

}

 

var bar = function (a, b){

     console.log( this .x);

    console.log(a,  b);

}

 

bar(2); // undefined

 

var boundFunc = bar.bind(foo, 1);

 

boundFunc(); // 3