Create javascript object with null prototype without using Object.create

Question

I need to find a way to create a JavaScript object with null prototype.

I'm not allowed to use the Object.create function.

I tried instantiating a constructor like new Constructor() , but the returned object always has a non- null prototype, even if Constructor.prototype === null .

Answer 1

Such an object already exists, it's Object.prototype , so your code is as simple as

x = Object.prototype

but you cannot create a new object like this, because new always sets the proto to an object:

If Type(proto) is not Object, set the [[Prototype]] internal property of obj to the standard built-in Object prototype object as described in 15.2.4. @ http://ecma-international.org/ecma-262/5.1/#sec-13.2.2

You can manipulate __proto__ directly

a = {}
a.__proto__ = null

Answer 2

var a = {};
a.prototype = null;
alert(a.prototype);

Answer 3

The usual way to create an object that inherits from another without Object.create is instantiating a function with the desired prototype . However, as you say it won't work with null :

 function Null() {} Null.prototype = null; var object = new Null(); console.log(Object.getPrototypeOf(object) === null); // false :( 

But luckily, ECMAScript 6 introduces classes. The approach above won't directly work neither because the prototype property of an ES6 class is non-configurable and non-writable.

However, you can take advantage of the fact that ES6 classes can extend null . Then, instead of instantiating, just get the prototype of the class:

 var object = (class extends null {}).prototype; delete object.constructor; console.log(Object.getPrototypeOf(object) === null); // true :)