Create an Object based on an existing object

Question

I'm new to Prototypal inheritance and I've been stuck in an easy task

I have something like this:

var test1 = {
       clear : function () { 
         alert('hey');
       } 

 }

 var test2 = {
       varB : 2

 }

I would like to test2 extend from test1. Can anyone give me a direction? Should I still use Object.create, or maybe a function + call method? Im a bit confused here.

Every example that i found are based on extending and then setting attributes, methods, etc.. But my object is already declared here.

Thanks!

javascriptweblog.wordpress.com/2010/06/07/…

tomaroo
– tomaroo

2014-09-05 15:23:45 +00:00
Commented Sep 5, 2014 at 15:23 — tomaroo
– tomaroo, Commented Sep 5, 2014 at 15:23

Felix Kling · Accepted Answer · 2014-09-05 15:29:17Z

1

In modern browsers, you can use Object.setPrototypeOf:

Object.setPrototypeOf(test2, test1);

There is currently no other (official) way to change the prototype of an existing object.

If you are just creating a simple object, you can use Object.create:

var test2 = Object.create(test1);
test2.varB = 2; // or Object.assign(test2, {varB: 2});

If you don't actually need inheritance, merging the objects with Object.assign would be an option:

Object.assign(test2, test1);

This simply copies the properties from test1 to test2. Unlike with inheritance, changes to test1 don't impact test2.

For more information, I suggest to have a look at

edited Sep 5, 2014 at 15:29

answered Sep 5, 2014 at 15:23

Felix Kling

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Comments

chestnut · Accepted Answer · 2014-09-05 15:22:42Z

0

Your can use prototype to do inheritance. But it just one of some inherit ways in javascript.

function test1() {}
test1.prototype.clear = function () {
    alert('hey');
}

function test2() {}
test2.prototype = new test1();
test2.prototype.varB = 2;

var test2Instance = new test2();

And search more javasrcipt inheritance methods with google by yourself.

answered Sep 5, 2014 at 15:22

chestnut

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Comments

javiyu · Accepted Answer · 2014-09-05 15:23:27Z

0

A very basic approach would be

test2.__proto__ = Object.create(test1)

So you will have clear function available in test2 object.

edited Sep 5, 2014 at 15:23

answered Sep 5, 2014 at 15:14

javiyu

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1 Comment

t.niese Over a year ago

MDN Object.prototype.__proto__ :[...]The __proto__ property is deprecated and should not be used.[...]

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