Deep Equal

mediumcodingJavaScriptObjectsRecursion~25 min

Asked at Google, Meta, Amazon

Overview

Implement deepEqual(a, b) that returns true if two values are deeply equal.

Constraints

Handle primitives, objects, arrays, null
Objects compared by keys and values, not reference
Arrays compared element by element

Examples

deepEqual({ a: 1, b: { c: 2 }}, { a: 1, b: { c: 2 }}); // true
deepEqual([1, [2]], [1, [3]]); // false

Solution

Reveal solution

function deepEqual(a, b) {
  if (a === b) return true;
  if (a === null || b === null || typeof a !== 'object' || typeof b !== 'object') return false;
  if (Array.isArray(a) !== Array.isArray(b)) return false;
  const keysA = Object.keys(a);
  const keysB = Object.keys(b);
  if (keysA.length !== keysB.length) return false;
  return keysA.every(key => deepEqual(a[key], b[key]));
}

deep-equal.js

Deep Equal

mediumcodingJavaScriptObjects

Overview

Implement deepEqual(a, b) that returns true if two values are deeply equal.

Constraints

Handle primitives, objects, arrays, null
Objects compared by keys and values, not reference
Arrays compared element by element

Examples

deepEqual({ a: 1, b: { c: 2 }}, { a: 1, b: { c: 2 }}); // true
deepEqual([1, [2]], [1, [3]]); // false

Solution

Reveal solution

function deepEqual(a, b) {
  if (a === b) return true;
  if (a === null || b === null || typeof a !== 'object' || typeof b !== 'object') return false;
  if (Array.isArray(a) !== Array.isArray(b)) return false;
  const keysA = Object.keys(a);
  const keysB = Object.keys(b);
  if (keysA.length !== keysB.length) return false;
  return keysA.every(key => deepEqual(a[key], b[key]));
}

NameTopicDifficulty

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