The Object create() method

Object.create() creates a new object with the prototype you provide.

const animal = {
  speak() {
    return 'Hello'
  }
}

const dog = Object.create(animal)

dog.speak() //'Hello'
Object.getPrototypeOf(dog) === animal //true

The properties are not copied from animal. JavaScript finds speak() by following the new object’s prototype chain.

The prototype must be an object or null. Any other value throws a TypeError.

See the MDN Object.create() reference and the ECMAScript specification for the complete behavior.

Add own properties

The optional second argument defines own properties on the new object:

const dog = Object.create(animal, {
  breed: {
    value: 'Siberian Husky',
    writable: true,
    enumerable: true,
    configurable: true
  }
})

dog.breed //'Siberian Husky'

Each entry must be a property descriptor, like the descriptors passed to Object.defineProperties().

Be careful with the defaults. If you only provide value, the property is not writable, enumerable, or configurable:

const dog = Object.create(animal, {
  breed: {
    value: 'Siberian Husky'
  }
})

Object.keys(dog) //[]

Create an object without a prototype

Pass null to create an object that does not inherit from Object.prototype:

const dictionary = Object.create(null)

dictionary.javascript = 'A programming language'
Object.getPrototypeOf(dictionary) //null

This is useful for a simple string-keyed dictionary. It also means methods such as toString() and hasOwnProperty() are not inherited.

Use Object.hasOwn(dictionary, 'javascript') to check an own property.

You can combine a chosen prototype with regular enumerable properties using Object.assign():

const dog = Object.assign(Object.create(animal), {
  breed: 'Siberian Husky'
})

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