Deep Clone

Zhenghao He
Zhenghao HeSenior Engineer, Ex-Amazon
Recommended duration to spend during interviews
25 mins
Users completed

The term "deep clone" is not formally defined in JavaScript's language specification, but is generally well understood in the community. A deep clone makes a copy of JavaScript value, leading to a completely new value that has no references pointing back to the properties in the original object (if it's an object). Any changes made to the deep-copied object will not affect the original object.

Implement a deepClone function that performs a deep clone operation on JavaScript objects. You can assume the input only contains JSON-serializable values (null, boolean, number, string, Array, Object) and will not contain any other objects like Date, Regex, Map or Set.


const obj1 = { user: { role: 'admin' } };
const clonedObj1 = deepClone(obj1);
clonedObj1.user.role = 'guest'; // Change the cloned user's role to 'guest'.
clonedObj1.user.role; // 'guest'
obj1.user.role; // Should still be 'admin'.
const obj2 = { foo: [{ bar: 'baz' }] };
const clonedObj2 = deepClone(obj2);[0].bar = 'bax'; // Modify the original object.[0].bar; // 'bax'[0].bar; // Should still be 'baz'.