javascript - Newbie meminta bantuan: Mengapa Console.log di sini kembali tidak ditentukan?

Question

function d(){this.get=function(){this.getNum()}};
d.prototype.getName=function(){return 3;};
var d = new d();
console.log(d.get());//undefined

Mengapa undefined ditunjukkan di sini? Daripada 3? Sila jawab

Answer 1

function d(){this.get=function(){return this.getName()}};
d.prototype.getName=function(){return 3;};
var d = new d();
console.log(d.get());//undefined

Answer 2

function d(){this.get=function(){return this.getNum()}};

Apa kata anda

Answer 3

function d(){this.get=function(){return this.getName();}};
d.prototype.getName=function(){return 3;};
var d = new d();
console.log(d.get());

Bandingkan untuk diri sendiri

Answer 4

nombor nama

Answer 5

this.getnum改成this.getname

Answer 6

function d(){
            this.get= function(){
                return this.getName()
            }
        };
        d.prototype.getName = function(){
            return 3;
        };
        var d = new d();
        console.log(d.get());