bind

Function.prototype.bind5 = function(){
    var self = this
    var arg = [...arguments].slice(1)
    var fNop = function(){}
    var fbound = function(){
        var args = [...arguments]
        arg = arg.concat(args)
        self.apply(this instanceof self ? this : context,arg)
    }
    //做出修改
    fNop.prototype = this.prototype
    fbound.prototype = new fNop();
    return fbound
}