What is difference between creating object using Object.create() and Object.assign()?
Let's compare obj1
and obj2
in this code:
var target1 = {}, target2 = {};
var obj1 = Object.create(target1, {myProp: {value: 1}});
var obj2 = Object.assign(target2, {myProp: 1});
Prototypical chain
Object.create
creates a new object with the specified [[Prototype]], and Object.assign
assigns the properties directly on the specified object:
obj1 !== target1;
obj2 === target2;
The prototypical chains of obj1
and obj2
look like
obj1 --> target1 --> Object.prototype --> null
obj2 --------------> Object.prototype --> null
Properties
Object.create
defines properties and Object.assign
only assigns them.
When creating a property, assignments will create it as configurable, writable and enumerable. When defining a property, you can specify those flags, but by default it's not configurable, nor writable and not enumerable.
Object.getOwnPropertyDescriptor(obj1, 'myProp');
// { value: 1, writable: false, enumerable: false, configurable: false }
Object.getOwnPropertyDescriptor(obj2, 'myProp');
// { value: 1, writable: true, enumerable: true, configurable: true }
Object.assign()
provides shallow copying (Only properties and methods) and it will override the method and property declared.
while Object.create()
provides Deep copying provides prototype chain.