fast-is-equal

Blazing-fast equality checks, minus the baggage. A lean, standalone alternative to Lodash’s isEqual—because speed matters.

Installation

Using yarn:

yarn add fast-is-equal

Using npm:

npm install fast-is-equal

Usage

import { fastIsEqual } from 'fast-is-equal';

console.log(fastIsEqual(1, 1)); // true
console.log(fastIsEqual({ a: 1 }, { a: 1 })); // true
console.log(fastIsEqual([1, 2], [1, 3])); // false

Features

• Lightweight and dependency-free.
• Handles primitives, objects, arrays, Maps, Sets, circular references, and more.
• Optimized for performance (see benchmarks).

Benchmarks

fast-is-equal outperforms Lodash’s isEqual in most cases. Run npm run benchmark locally to compare:

Performance Comparison: fastIsEqual vs Lodash isEqual
Iterations per test case: 1000000
----------------------------------------
Test Case 1: Numbers
  fastIsEqual: 0.000003 ms
  Lodash isEqual: 0.000006 ms
  Difference (fastIsEqual - Lodash): -0.000002 ms
  fastIsEqual is 1.62x faster than Lodash
----------------------------------------
Test Case 2: Strings
  fastIsEqual: 0.000005 ms
  Lodash isEqual: 0.000005 ms
  Difference (fastIsEqual - Lodash): -0.000000 ms
  fastIsEqual is 1.08x faster than Lodash
----------------------------------------
Test Case 3: Booleans
  fastIsEqual: 0.000005 ms
  Lodash isEqual: 0.000005 ms
  Difference (fastIsEqual - Lodash): -0.000000 ms
  fastIsEqual is 1.06x faster than Lodash
----------------------------------------
Test Case 4: NaN
  fastIsEqual: 0.000006 ms
  Lodash isEqual: 0.000012 ms
  Difference (fastIsEqual - Lodash): -0.000006 ms
  fastIsEqual is 1.98x faster than Lodash
----------------------------------------
Test Case 5: Simple Object (equal)
  fastIsEqual: 0.000097 ms
  Lodash isEqual: 0.000271 ms
  Difference (fastIsEqual - Lodash): -0.000174 ms
  fastIsEqual is 2.80x faster than Lodash
----------------------------------------
Test Case 6: Simple Object (unequal)
  fastIsEqual: 0.000105 ms
  Lodash isEqual: 0.000271 ms
  Difference (fastIsEqual - Lodash): -0.000165 ms
  fastIsEqual is 2.57x faster than Lodash
----------------------------------------
Test Case 7: Nested Object (equal)
  fastIsEqual: 0.000184 ms
  Lodash isEqual: 0.000835 ms
  Difference (fastIsEqual - Lodash): -0.000651 ms
  fastIsEqual is 4.53x faster than Lodash
----------------------------------------
Test Case 8: Nested Object (unequal)
  fastIsEqual: 0.000197 ms
  Lodash isEqual: 0.000850 ms
  Difference (fastIsEqual - Lodash): -0.000653 ms
  fastIsEqual is 4.31x faster than Lodash
----------------------------------------
Test Case 9: Array of Primitives (equal)
  fastIsEqual: 0.000017 ms
  Lodash isEqual: 0.000102 ms
  Difference (fastIsEqual - Lodash): -0.000085 ms
  fastIsEqual is 5.95x faster than Lodash
----------------------------------------
Test Case 10: Array of Primitives (unequal)
  fastIsEqual: 0.000015 ms
  Lodash isEqual: 0.000103 ms
  Difference (fastIsEqual - Lodash): -0.000088 ms
  fastIsEqual is 6.79x faster than Lodash
----------------------------------------
Test Case 11: Array of Objects (equal)
  fastIsEqual: 0.000078 ms
  Lodash isEqual: 0.000638 ms
  Difference (fastIsEqual - Lodash): -0.000560 ms
  fastIsEqual is 8.15x faster than Lodash
----------------------------------------
Test Case 12: Circular Reference
  fastIsEqual: 0.000095 ms
  Lodash isEqual: 0.000493 ms
  Difference (fastIsEqual - Lodash): -0.000399 ms
  fastIsEqual is 5.22x faster than Lodash
----------------------------------------
Test Case 13: Map (equal)
  fastIsEqual: 0.000074 ms
  Lodash isEqual: 0.001383 ms
  Difference (fastIsEqual - Lodash): -0.001309 ms
  fastIsEqual is 18.67x faster than Lodash
----------------------------------------
Test Case 14: Map (unequal)
  fastIsEqual: 0.000076 ms
  Lodash isEqual: 0.001330 ms
  Difference (fastIsEqual - Lodash): -0.001255 ms
  fastIsEqual is 17.59x faster than Lodash
----------------------------------------
Test Case 15: Set (equal)
  fastIsEqual: 0.000073 ms
  Lodash isEqual: 0.000949 ms
  Difference (fastIsEqual - Lodash): -0.000876 ms
  fastIsEqual is 13.07x faster than Lodash
----------------------------------------
Test Case 16: Set (unequal)
  fastIsEqual: 0.000070 ms
  Lodash isEqual: 0.000930 ms
  Difference (fastIsEqual - Lodash): -0.000860 ms
  fastIsEqual is 13.22x faster than Lodash
----------------------------------------
Test Case 17: Empty Object vs Array
  fastIsEqual: 0.000009 ms
  Lodash isEqual: 0.000043 ms
  Difference (fastIsEqual - Lodash): -0.000034 ms
  fastIsEqual is 4.74x faster than Lodash
----------------------------------------
Test Case 18: Map vs Set
  fastIsEqual: 0.000018 ms
  Lodash isEqual: 0.000469 ms
  Difference (fastIsEqual - Lodash): -0.000452 ms
  fastIsEqual is 26.55x faster than Lodash
----------------------------------------
Average Performance:
  fastIsEqual: 0.000063 ms
  Lodash isEqual: 0.000483 ms
  fastIsEqual is on average 7.71x faster than Lodash

License

MIT

MIT License

Copyright (c) 2025 Jairaj Jangle

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