CODEWITHSUNDEEP
javascript
Joe.wang
Joe.wang

Reputation: 11791

When to use __proto__ and when to use prototype

All, I always confused by the __proto__ and prototype properties of the object, Especially In the prototype inheritance chain, let's say there is an object named test, and the code is below.

test.add();//try to call a method name add.

in my understanding ,I draw a diagram to demo the flow of searching . But I am not sure if it is right .please help to review it .thanks.

enter image description here

Corrected it based on the Minko Gechev's answer.

enter image description here

Upvotes: 1

Views: 144

Answers (1)

Minko Gechev
Minko Gechev

Reputation: 25682

Only functions have prototype property but any object has __proto__ property.

Usually it's not a good idea to change the __proto__ property explicit better use something like Object.create.

Here is an example:

function Person() {
}
var proto = { bar: 'baz' };
Person.prototype = proto;

In this way any object which you create with the constructor function Person will have __proto__ property referencing to proto

As conclusion we can say that:

The prototype property is used only for the constructor function it sets the __proto__ property of all objects which will be created with this constructor function. When the interpreter is looking for property of a given object foo it firstly use the object foo after that foo.__proto__ after that foo.__proto__.__proto__ and so on while it find the property or not.

Upvotes: 3

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