How to copy properties and methods from one object to another object in JavaScript?

Published June 18, 2020

Properties and methods can be copied from one object to another object using the Object.assign() method.


Let's say you have 2 objects obj1 and obj2.

const obj1 = { name: "Object 1" };

const obj2 = { bio: "This is my bio" };

We can copy the properties and methods from obj2 to obj1 using the Object.assign() method.

const obj1 = { name: "Object 1" };

const obj2 = { bio: "This is my bio" };

// Copy from obj2 to obj1
Object.assign(obj1, obj2);

/*

obj1 - Result:
--------------

{
    name: "Object 1",
    bio: "This is my bio"
}

*/
  • The method takes 2 parameters.
  • The first parameter is the target object.
  • The second parameter is the source object in which you want the contents to be copied.
  • The method returns the target object.

If the target object has the same property name as the source object it will be overridden.

const obj1 = { name: "Object 1", age: 23 };

const obj2 = { bio: "This is my bio", age: 34 };

// Copy from obj2 to obj1
Object.assign(obj1, obj2);

/*

obj1 - Result:
--------------

{
    name: "Object 1", 
    age: 34, 
    bio: "This is my bio"
}

*/

The property age: 23 in obj1 is overridden by the property age: 34 in obj2.

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