Javascript Objects returns 'undefined'

Question

Hello guys i'm trying objects in javascript/node.js, actually i'm having a hard time on objects with functions inside them. This is my sample code whish the output should be:

Rohan says: Hello World

Here is my func.js

var myObject = function(name) {
    console.log(this.name + ' says: ');
    this.talk = function(msg) {
        console.log(msg);
        }
};

var phil = function (name) {
    this.name = name;
};

phil.prototype = new myObject();
var man = new phil('Rohan');
man.talk('Hello World');

I hope you can help me solve this problem in my code. Thanks guys.

Your `myobject` function has an unused `name` parameter, and uses a (not initialized) `name` property. What do you want? Which of the two "classes" should be responsible for the name? In my answer it works, but is still confusing. — Bergi, Sep 19 '13 at 03:22

score 2 · Answer 1 · edited May 23 '17 at 12:28

See Correct javascript inheritance. Don't use the new keyword for creating the prototype (you don't want to initialize it like an instance). Initialise the instance by applying the parent constructor. And for naming conventions: uppercase constructors would be nice.

function MyObject() {
    console.log(this.name + ' got created');
}
MyObject.prototype.talk = function(msg) {
    console.log("and says "+msg);
};

function Phil(name) {
    this.name = name;
    MyObject.call(this);
}
Phil.prototype = Object.create(MyObject.prototype);

var man = new Phil('Rohan');
man.talk('Hello World');

score 1 · Answer 2 · answered Sep 19 '13 at 03:21

1

Modify your talk function to

this.talk = function (msg) {
    console.log(this.name + ' says: ' + msg);
}

answered Sep 19 '13 at 03:21

Huy Le

657
5
17

How is that going to solve the problem ? – The Alpha Sep 19 '13 at 03:22
1

This is not about how to print the name but instead it's about prototypal inheritance. – The Alpha Sep 19 '13 at 03:24
Just want to help him get the intended output. More thoroughly explain already wrote by Bergi. – Huy Le Sep 19 '13 at 03:26

score 1 · Accepted Answer · answered Sep 19 '13 at 03:29

1

var myObject = function(name) {
    this.talk = function(msg) {
        console.log(msg);
    },
    this.setName = function(name) {
        this.name = name;
        console.log(name + ' says: ');
    }
};

var phil = function (name) {
    this.setName(name);
};

phil.prototype = new myObject();
var man = new phil('Rohan');
man.talk('Hello World');

answered Sep 19 '13 at 03:29

Popsyjunior

185
10

This is what i'm saying. This Code. :) Thanks Popsyjunior. – Joenel de Asis Sep 19 '13 at 03:39
Try to call `man.talk('Hello world')` once again – Huy Le Sep 19 '13 at 03:43
[Do not use `phil.prototype = new myObject();`](http://stackoverflow.com/questions/12592913/what-is-the-reason-to-use-the-new-keyword-here) – Bergi Sep 19 '13 at 03:50
You're welcome. I'll like to believe that it's a homework or something you're trying out. @Bergi is right In real life applications, you'll want to use standard javascript inheritance. – Popsyjunior Sep 19 '13 at 07:43

Javascript Objects returns 'undefined'

3 Answers3