Node.js Inheritance

Question

I have inherited a class from another JS, and added few prototype function over Parent functions. When i create a new instance of child, i want to call the constructor of parent. Please suggest a way.

Parent

function Parent() { .. } 
    Parent.prototype.fn1 = function(){};
    exports.create = function() {
    return (new Parent());
};

Child

var parent = require('parent');
Child.prototype = frisby.create();
function Child() { .. } 
Child.prototype.fn2 = function(){};
exports.create = function() {
    return (new Child());  
};

Knase · Accepted Answer · 2014-05-07 20:36:53Z

1

You can use module util. Look simple example:

    var util = require('util');

function Parent(foo) {
    console.log('Constructor:  -> foo: ' + foo);
}

Parent.prototype.init = function (bar) {
    console.log('Init: Parent -> bar: ' + bar);
};

function Child(foo) {
    Child.super_.apply(this, arguments);
    console.log('Constructor: Child');
}


util.inherits(Child, Parent);

Child.prototype.init = function () {
     Child.super_.prototype.init.apply(this, arguments); 
     console.log('Init: Child');
};

var ch = new Child('it`s foo!');

ch.init('it`s init!');

answered May 7, 2014 at 20:36

Knase

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Comments

Anatoliy · Accepted Answer · 2012-10-27 01:13:21Z

0

First of all, do not export create method, export constructor (Child, Parent). Then you will be able to call parent's constructor on child:

var c = new Child;
Parent.apply(c);

About inheritance. In node you can use util.inherits method, which will setup inheritance and setup link to superclass. If you don't need link to superclass or just want to inherit manually, use proto:

Child.prototype.__proto__ = Parent.prototype;

answered Oct 27, 2012 at 1:13

Anatoliy

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2 Comments

user1748253 Over a year ago

Problem is, Parent class is from a framework. I dont like to change the source code of a framework. Is there any other way??

Anatoliy Over a year ago

Of course no. There's way around: create instance of parent, create instance of child, and then: child.constructor.prototype.__proto__ = parent.constructor.prototype

Teemu Ikonen · Accepted Answer · 2012-10-27 01:26:39Z

0

Parent (parent.js)

function Parent() {
}

Parent.prototype.fn1 = function() {}
exports.Parent = Parent;

Child

var Parent = require('parent').Parent,
    util = require('util');

function Child() {
   Parent.constructor.apply(this);
}
util.inherits(Child, Parent);

Child.prototype.fn2 = function() {}

answered Oct 27, 2012 at 1:26

Teemu Ikonen

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1 Comment

user1748253 Over a year ago

Problem is, Parent class is from a framework. I dont like to change the source code of a framework. Is there any other way??

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