Summary

Creates a new object with the specified prototype object and properties.

Syntax

Object.create(proto [, propertiesObject ])

Parameters

proto

The object which should be the prototype of the newly-created object.

propertiesObject

If specified and not undefined, an object whose enumerable own properties (that is, those properties defined upon itself and not enumerable properties along its prototype chain) specify property descriptors to be added to the newly-created object, with the corresponding property names.

Description

Throws a TypeError exception if the proto parameter isn't null or an object.

Examples

var o;

// create an object with null as prototype
o = Object.create(null);


o = {};
// is equivalent to:
o = Object.create(Object.prototype);


function Constructor(){}
o = new Constructor();
// is equivalent to:
o = Object.create(Constructor.prototype);
// Of course, if there is actual initialization code in the Constructor function, the Object.create cannot reflect it


// create a new object whose prototype is a new, empty object
// and a adding single property 'p', with value 42
o = Object.create({}, { p: { value: 42 } })

// by default properties ARE NOT writable, enumerable or configurable:
o.p = 24
o.p
//42

o.q = 12
for (var prop in o) {
   console.log(prop)
}
//"q"

delete o.p
//false

//to specify an ES3 property
o2 = Object.create({}, { p: { value: 42, writable: true, enumerable: true, configurable: true } });

Cross-browser compatibility

Based on Kangax's compat table.

if (!Object.create) {
    Object.create = function (o) {
        if (arguments.length > 1) {
            throw new Error('Object.create implementation only accepts the first parameter.');
        }
        function F() {}
        F.prototype = o;
        return new F();
    };
}

See also

• Object.defineProperty
• Object.defineProperties
• Object.prototype.isPrototypeOf
• John Resig's post on getPrototypeOf