Use of Object.assign in JavaScript

The Object.assign() method is used to copy the values of all of the object's own properties(enumerable only) from one or more source objects to a target object. It will return the target object.

Example

const targetObj = { a: 1, b: 2 };
const sourceObj = { b: 4, c: 5 };
const returnedTarget = Object.assign(targetObj, sourceObj);
console.log(targetObj);
console.log(returnedTarget);
console.log(returnedTarget === targetObj);
console.log(sourceObj);

Output

{ a: 1, b: 4, c: 5 }
{ a: 1, b: 4, c: 5 }
true
{ b: 4, c: 5 }

Note −

• sourceObj did not change.

• returnedTarget and targetObj are the same.

• The Object.assign() method only copies enumerable and own properties from a source object to a target object. It uses [[Get]] on the source and [[Set]] on the target, so it will invoke getters and setters.