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Nitin Reddy
Nitin Reddy

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Deep cloning of an object in JavaScript...

As JavaScript developers, we most often than not come across a situation where we want to clone an object and reuse it to perform some operations.

And we usually follow well-known approaches to deep clone the object:-

  • lodash's cloneDeep method
  • JSON.parse(JSON.stringify(object))

What if I say that you are not supposed to use the above two approaches and you should create your custom method to deep clone the object?

I have an answer for that. Let's write a utility method that would help us in achieving the deep cloning of an object.


Let us say that I have a nested object as below

let emptyStack = {
  feTools: 'JS, React, NextJS, Tailwindcss, Netlify',
  react: {
    baseConcepts: 'props, states, hooks',
    advancedConcepts: {
      hoc: 'composition of the functions',
      contextApi: 'Sharing the data without prop drilling'
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So in the above, as you can see we have the nested objects inside emptyStack. Let us try to understand and evaluate what all steps are required to be executed to achieve the deep cloning of an object.

Pseudo code


  1. Initialize a new empty object
  2. Iterate over the keys of an object and check if the key-value pair is an object
  3. And based on the result of Step#2 update the empty object with the new properties.
  4. Repeat the Step#2 and #3 till the last element of an object is evaluated.

The ultimate utility method

function deepCopy(currentObj) {
  let newObj = Array.isArray(currentObj) ? [] : {}; //Step#1
  for (let key in currentObj) { //Step#2
    let property = currentObj[key];
    if (typeof property === "object") {
      newObj[key] = deepCopy(property); //Step#3
    } else {
      newObj[key] = property; //Step#3
  return newObj;
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let deepClonedObject = deepCopy(emptyStack)

/** Output
{"feTools":"JS, React, NextJS, Tailwindcss, Netlify","react":{"baseConcepts":"props, states, hooks","advancedConcepts":{"hoc":"composition of the functions","contextApi":"Sharing the data without prop drilling"}}} */
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What all concepts are used in the above method?

  • Recursive function
  • Object keys iteration

Recursive function


Deep cloning an object is really useful in the scenarios where you want the back referencing to happen for a cloned object.
There are more posts on the way related to the lists...So keep reading.

Thanks in advance for reading this article...🚀

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