isEqual

Problem

You need deep equality between two values — for example change-detection, deduplication, or memoization key comparison.

Solution

Use isEqual(a, b, options?) for deep equality. Pass { depth: 'shallow' } to compare only one level by reference.

import { isEqual } from '@vielzeug/arsenal';

isEqual({ a: 1 }, { a: 1 }); // true
isEqual([1, [2, 3]], [1, [2, 3]]); // true
isEqual(new Date('2024'), new Date('2024')); // true

isEqual({ a: 1 }, { a: 2 }); // false

Shallow mode

import { isEqual } from '@vielzeug/arsenal';

const arr = [1, 2, 3];
isEqual({ arr }, { arr }, { depth: 'shallow' }); // true — same reference
isEqual([1, 2], [1, 2], { depth: 'shallow' }); // false — different references

Pitfalls

• Deep equality is recursive — avoid on very large graphs without memoization.
• Handles circular references, Date, Map, and Set.

Related

• isMatch
• diff