Object.create() vs. Object.assign()

What are the differences from Object.create() and Object.assign()? Let’s explore!

Object.create() vs. Object.assign()

1. Test for prototypal relationships

Object.create

let dog = {
  barks() {
    console.log('woof woof');
  }
}
let menno = Object.create(dog);
Object.getPrototypeOf(menno) === dog; // true
dog.isPrototypeOf(menno); // true

Object.assign

let dog = {
  barks() {
    console.log('woof woof');
  }
}
let menno = Object.assign({}, dog);
Object.getPrototypeOf(menno) === dog; // false
dog.isPrototypeOf(menno); // false

2. Adding new property or method to a newly created object

Object.create

let dog = {
  barks() {
    console.log('woof woof');
  }
}
let menno = Object.create(dog, {
  jumps: {
    value: function () {
      console.log('jumping!');
    },
    writable: false,
  },
});
menno.jumps(); // jumping
menno.barks(); // woof woof

Object.assign

let dog = {
  barks() {
    console.log('woof woof');
  }
}
let menno = Object.assign({}, dog, {
  jumps() {
    console.log('Jumping!');
  }
});
menno.jumps(); // jumping
menno.barks(); // woof woof

3. Access to methods up the prototypal chain

Object.create

let dog = {
  barks() {
    console.log('woof woof');
  }
}
let jackie = Object.create(dog);
Object.defineProperties(jackie, {
  swims: {
    value: function() {
      console.log('swimming swimming');
    },
    writable: false;
  },
});
let menno = Object.create(jackie);
menno.swims(); // swimming swimming
menno.barks(); // woof woof

Object.assign

let dog = {
  barks() {
    console.log('woof woof');
  }
}
let jackie = Object.create(dog);
let menno = Object.assign({}, jackie);
menno.barks(); // TypeError, menno.barks is not a function

4. Combine the deep cloning functionalities of Object.create() with the flexibility of Object.assign()

Object.assign(Object.create(obj), ...sourceObjs)

let dog = {
  barks() {
    console.log('woof woof');
  }
}
let menno = Object.assign(Object.create(dog), {
  swims() {
    console.log('swimming swimming');
  }
});
menno.swims(); // swimming swimming
menno.barks(); // woof woof