CODEWITHSUNDEEP
javascriptnode.js
Alexander Mills
Alexander Mills

Reputation: 100020

Is there a way to get prototype of an object that was initialized with {}

In JavaScript, if I initialize an object like so:

var foo = {};

is there a way to get the prototype of that object? The prototype quite well may be undefined. But actually, what I really want is just the defined fields and functions/methods that foo may have:

var foo = {

field1: '',
method1: function(){}

};

I am trying to create a classical inheritance system, but Object.create() seems to want arguments that represent prototypes and nothing else.

In other words, I want var bar = {} to inherit from foo. But both bar and foo are objects initialized with {}.

How can I add the methods from one object to another with or without dealing with prototypes?

Upvotes: 0

Views: 101

Answers (3)

G Roy
G Roy

Reputation: 166

When you instantiate an object with new ({} is the same as new Object()), the prototype becomes its properties. Here is a simple example of prototypal inheritance : 

// Foo constructor
var Foo = function() {};
Foo.prototype = {
    field1: '',
    method1: function(){}
};

// bar constructor
var Bar = function(){
    Foo.call(this); // calling the parent ctor
};
Bar.prototype = Object.create(Foo.prototype); // inherit from Foo
Bar.prototype.constructor = Bar; // set the ctor just in case it was set by Foo

var bar_instance = new Bar();
bar_instance.method1(); // <-- it works!

I would suggest you go read the code for Google's Closure Library, PrototypeJS and Mootools Class system to inspire you in your endeavor.

Hope this helps.

Upvotes: 2

Rakesh_Kumar
Rakesh_Kumar

Reputation: 1442

You may try this:

http://jsfiddle.net/kc0Lshrp/1/

var foo = {};
foo.constructor.prototype.field1='FOO';
foo.constructor.prototype.method1=function(){ alert(this.field1)};
var bar={field1:'BAR'};
bar.prototype=Object.create(foo);
bar.method1();

Upvotes: 1

Bhojendra Rauniyar
Bhojendra Rauniyar

Reputation: 85545

You may use Object.create():

var foo = {
   field1: '',
   method1: function(){}
};
var bar = Object.create(foo);

Upvotes: 1

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