Deep Clone

mediumcodingJavaScriptObjectsRecursion~25 min

Asked at Google, Meta, Stripe

Overview

Implement deepClone(value) that creates a deep copy of the input. Must handle objects, arrays, nested structures, null, and primitives.

Constraints

No JSON.parse(JSON.stringify())
Handle nested objects and arrays
Primitives returned as-is

Examples

const obj = { a: 1, b: { c: 2 } };
const clone = deepClone(obj);
clone.b.c = 99;
obj.b.c; // still 2

Solution

Reveal solution

function deepClone(value) {
  if (value === null || typeof value !== 'object') return value;
  if (Array.isArray(value)) return value.map(item => deepClone(item));
  const result = {};
  for (const key of Object.keys(value)) result[key] = deepClone(value[key]);
  return result;
}

deep-clone.js

Deep Clone

mediumcodingJavaScriptObjects

Overview

Implement deepClone(value) that creates a deep copy of the input. Must handle objects, arrays, nested structures, null, and primitives.

Constraints

No JSON.parse(JSON.stringify())
Handle nested objects and arrays
Primitives returned as-is

Examples

const obj = { a: 1, b: { c: 2 } };
const clone = deepClone(obj);
clone.b.c = 99;
obj.b.c; // still 2

Solution

Reveal solution

function deepClone(value) {
  if (value === null || typeof value !== 'object') return value;
  if (Array.isArray(value)) return value.map(item => deepClone(item));
  const result = {};
  for (const key of Object.keys(value)) result[key] = deepClone(value[key]);
  return result;
}

NameTopicDifficulty

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