JavaScript: Create a deep clone of an object

JavaScript fundamental (ES6 Syntax): Exercise-71 with Solution

Deep Clone Object

Write a JavaScript program to create a deep clone of an object.

• Use recursion.
• Check if the passed object is null and, if so, return null.
• Use Object.assign() and an empty object ({}) to create a shallow clone of the original.
• Use Object.keys() and Array.prototype.forEach() to determine which key-value pairs need to be deep cloned.
• If the object is an Array, set the clone's length to that of the original and use Array.from(clone) to create a clone.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2
// Define a function 'deepClone' to create a deep clone of an object.
const deepClone = obj => {
  // Create a shallow clone of the object using Object.assign
  let clone = Object.assign({}, obj);
  // Iterate over the keys of the clone
  Object.keys(clone).forEach(
    key => {
      // If the value of the key is an object, recursively call deepClone
      clone[key] = typeof obj[key] === 'object' ? deepClone(obj[key]) : obj[key];
    }
  );
  // If the original object is an array, update the length of the clone and convert it to an array
  return Array.isArray(obj) ? (clone.length = obj.length) && Array.from(clone) : clone;
};

// Example usage:
const a = { foo: 'bar', obj: { a: 1, b: 2 } };
const b = deepClone(a);  
console.log(b);

Output:

{"foo":"bar","obj":{"a":1,"b":2}}

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-71-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that creates a deep clone of an object, including nested objects and arrays.
• Write a JavaScript function that recursively copies all properties of an object to produce an independent clone.
• Write a JavaScript program that compares a deep-cloned object with the original to ensure no references are shared.

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