fast-is-equal

A fork of JairajJangle/fast-is-equal that works with modern bundlers without plugins (full ESNext)

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

Installation

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: 1,000,000
════════════════════════════════════════════════════════════════════════════════
Test 1: Numbers
  fastIsEqual:    0.000005 ms
  Lodash isEqual: 0.000005 ms
  ➡️  Speed: 1.11x faster
────────────────────────────────────────────────────────────────────────────────
Test 2: Strings
  fastIsEqual:    0.000006 ms
  Lodash isEqual: 0.000008 ms
  ✅ Speed: 1.39x faster
────────────────────────────────────────────────────────────────────────────────
Test 3: Booleans
  fastIsEqual:    0.000005 ms
  Lodash isEqual: 0.000005 ms
  ➡️  Speed: 1.01x faster
────────────────────────────────────────────────────────────────────────────────
Test 4: NaN
  fastIsEqual:    0.000009 ms
  Lodash isEqual: 0.000012 ms
  ✅ Speed: 1.36x faster
────────────────────────────────────────────────────────────────────────────────
Test 5: Large Numbers
  fastIsEqual:    0.000006 ms
  Lodash isEqual: 0.000006 ms
  ⚠️  Speed: 0.99x slower
────────────────────────────────────────────────────────────────────────────────
Test 6: Negative Zero
  fastIsEqual:    0.000005 ms
  Lodash isEqual: 0.000005 ms
  ➡️  Speed: 1.00x faster
────────────────────────────────────────────────────────────────────────────────
Test 7: Empty Objects
  fastIsEqual:    0.000127 ms
  Lodash isEqual: 0.000222 ms
  ✅ Speed: 1.75x faster
────────────────────────────────────────────────────────────────────────────────
Test 8: Single Property Object
  fastIsEqual:    0.000100 ms
  Lodash isEqual: 0.000264 ms
  🚀 Speed: 2.64x faster
────────────────────────────────────────────────────────────────────────────────
Test 9: Simple Object (equal)
  fastIsEqual:    0.000131 ms
  Lodash isEqual: 0.000304 ms
  🚀 Speed: 2.32x faster
────────────────────────────────────────────────────────────────────────────────
Test 10: Simple Object (unequal)
  fastIsEqual:    0.000100 ms
  Lodash isEqual: 0.000287 ms
  🚀 Speed: 2.87x faster
────────────────────────────────────────────────────────────────────────────────
Test 11: Object with null prototype
  fastIsEqual:    0.000196 ms
  Lodash isEqual: 0.000310 ms
  ✅ Speed: 1.59x faster
────────────────────────────────────────────────────────────────────────────────
Test 12: Nested Object (equal)
  fastIsEqual:    0.000385 ms
  Lodash isEqual: 0.000868 ms
  🚀 Speed: 2.26x faster
────────────────────────────────────────────────────────────────────────────────
Test 13: Nested Object (unequal)
  fastIsEqual:    0.000282 ms
  Lodash isEqual: 0.000847 ms
  🚀 Speed: 3.00x faster
────────────────────────────────────────────────────────────────────────────────
Test 14: Deeply Nested (5 levels)
  fastIsEqual:    0.000674 ms
  Lodash isEqual: 0.001482 ms
  🚀 Speed: 2.20x faster
────────────────────────────────────────────────────────────────────────────────
Test 15: Empty Arrays
  fastIsEqual:    0.000021 ms
  Lodash isEqual: 0.000083 ms
  🚀 Speed: 3.93x faster
────────────────────────────────────────────────────────────────────────────────
Test 16: Single Element Array
  fastIsEqual:    0.000022 ms
  Lodash isEqual: 0.000091 ms
  🚀 Speed: 4.07x faster
────────────────────────────────────────────────────────────────────────────────
Test 17: Array of Primitives (equal)
  fastIsEqual:    0.000024 ms
  Lodash isEqual: 0.000095 ms
  🚀 Speed: 3.97x faster
────────────────────────────────────────────────────────────────────────────────
Test 18: Array of Primitives (unequal)
  fastIsEqual:    0.000023 ms
  Lodash isEqual: 0.000103 ms
  🚀 Speed: 4.38x faster
────────────────────────────────────────────────────────────────────────────────
Test 19: Large Array of Numbers (100)
  fastIsEqual:    0.000392 ms
  Lodash isEqual: 0.000486 ms
  ➡️  Speed: 1.24x faster
────────────────────────────────────────────────────────────────────────────────
Test 20: Array of Strings
  fastIsEqual:    0.000032 ms
  Lodash isEqual: 0.000106 ms
  🚀 Speed: 3.33x faster
────────────────────────────────────────────────────────────────────────────────
Test 21: Mixed Type Array
  fastIsEqual:    0.000031 ms
  Lodash isEqual: 0.000103 ms
  🚀 Speed: 3.32x faster
────────────────────────────────────────────────────────────────────────────────
Test 22: Sparse Array
  fastIsEqual:    0.000036 ms
  Lodash isEqual: 0.000111 ms
  🚀 Speed: 3.12x faster
────────────────────────────────────────────────────────────────────────────────
Test 23: Array of Objects (equal)
  fastIsEqual:    0.000268 ms
  Lodash isEqual: 0.000644 ms
  🚀 Speed: 2.41x faster
────────────────────────────────────────────────────────────────────────────────
Test 24: Uint8Array
  fastIsEqual:    0.000059 ms
  Lodash isEqual: 0.000674 ms
  🚀 Speed: 11.34x faster
────────────────────────────────────────────────────────────────────────────────
Test 25: Float32Array
  fastIsEqual:    0.000060 ms
  Lodash isEqual: 0.000680 ms
  🚀 Speed: 11.30x faster
────────────────────────────────────────────────────────────────────────────────
Test 26: Large TypedArray (1000)
  fastIsEqual:    0.000944 ms
  Lodash isEqual: 0.013165 ms
  🚀 Speed: 13.95x faster
────────────────────────────────────────────────────────────────────────────────
Test 27: ArrayBuffer (small)
  fastIsEqual:    0.000092 ms
  Lodash isEqual: 0.001263 ms
  🚀 Speed: 13.74x faster
────────────────────────────────────────────────────────────────────────────────
Test 28: Dates (equal)
  fastIsEqual:    0.000023 ms
  Lodash isEqual: 0.000198 ms
  🚀 Speed: 8.63x faster
────────────────────────────────────────────────────────────────────────────────
Test 29: RegExp (equal)
  fastIsEqual:    0.000042 ms
  Lodash isEqual: 0.000417 ms
  🚀 Speed: 9.81x faster
────────────────────────────────────────────────────────────────────────────────
Test 30: RegExp (unequal flags)
  fastIsEqual:    0.000042 ms
  Lodash isEqual: 0.000431 ms
  🚀 Speed: 10.25x faster
────────────────────────────────────────────────────────────────────────────────
Test 31: Circular Reference
  fastIsEqual:    0.000136 ms
  Lodash isEqual: 0.000507 ms
  🚀 Speed: 3.72x faster
────────────────────────────────────────────────────────────────────────────────
Test 32: Mutual Circular
  fastIsEqual:    0.000275 ms
  Lodash isEqual: 0.000839 ms
  🚀 Speed: 3.04x faster
────────────────────────────────────────────────────────────────────────────────
Test 33: Empty Map
  fastIsEqual:    0.000058 ms
  Lodash isEqual: 0.000684 ms
  🚀 Speed: 11.84x faster
────────────────────────────────────────────────────────────────────────────────
Test 34: Map with primitives
  fastIsEqual:    0.000092 ms
  Lodash isEqual: 0.001487 ms
  🚀 Speed: 16.09x faster
────────────────────────────────────────────────────────────────────────────────
Test 35: Map (unequal)
  fastIsEqual:    0.000092 ms
  Lodash isEqual: 0.001406 ms
  🚀 Speed: 15.29x faster
────────────────────────────────────────────────────────────────────────────────
Test 36: Large Map (50 entries)
  fastIsEqual:    0.001059 ms
  Lodash isEqual: 0.025756 ms
  🚀 Speed: 24.32x faster
────────────────────────────────────────────────────────────────────────────────
Test 37: Empty Set
  fastIsEqual:    0.000058 ms
  Lodash isEqual: 0.000691 ms
  🚀 Speed: 11.96x faster
────────────────────────────────────────────────────────────────────────────────
Test 38: Set of numbers
  fastIsEqual:    0.000087 ms
  Lodash isEqual: 0.000958 ms
  🚀 Speed: 10.96x faster
────────────────────────────────────────────────────────────────────────────────
Test 39: Set (unequal)
  fastIsEqual:    0.000087 ms
  Lodash isEqual: 0.000939 ms
  🚀 Speed: 10.84x faster
────────────────────────────────────────────────────────────────────────────────
Test 40: Set of strings
  fastIsEqual:    0.000082 ms
  Lodash isEqual: 0.000940 ms
  🚀 Speed: 11.51x faster
────────────────────────────────────────────────────────────────────────────────
Test 41: Large Set (100 items)
  fastIsEqual:    0.000673 ms
  Lodash isEqual: 0.037564 ms
  🚀 Speed: 55.84x faster
────────────────────────────────────────────────────────────────────────────────
Test 42: Object vs Array
  fastIsEqual:    0.000009 ms
  Lodash isEqual: 0.000033 ms
  🚀 Speed: 3.62x faster
────────────────────────────────────────────────────────────────────────────────
Test 43: Map vs Set
  fastIsEqual:    0.000018 ms
  Lodash isEqual: 0.000485 ms
  🚀 Speed: 26.52x faster
────────────────────────────────────────────────────────────────────────────────
Test 44: String vs Number
  fastIsEqual:    0.000007 ms
  Lodash isEqual: 0.000006 ms
  ⚠️  Speed: 0.95x slower
────────────────────────────────────────────────────────────────────────────────
Test 45: Boolean vs Number
  fastIsEqual:    0.000006 ms
  Lodash isEqual: 0.000006 ms
  ⚠️  Speed: 0.99x slower
────────────────────────────────────────────────────────────────────────────────
Test 46: User Object
  fastIsEqual:    0.000188 ms
  Lodash isEqual: 0.000360 ms
  ✅ Speed: 1.91x faster
────────────────────────────────────────────────────────────────────────────────
Test 47: API Response
  fastIsEqual:    0.000672 ms
  Lodash isEqual: 0.001423 ms
  🚀 Speed: 2.12x faster
────────────────────────────────────────────────────────────────────────────────
Test 48: Config Object
  fastIsEqual:    0.000242 ms
  Lodash isEqual: 0.000491 ms
  🚀 Speed: 2.03x faster
────────────────────────────────────────────────────────────────────────────────
Test 49: State Object
  fastIsEqual:    0.000432 ms
  Lodash isEqual: 0.000810 ms
  ✅ Speed: 1.88x faster
────────────────────────────────────────────────────────────────────────────────
════════════════════════════════════════════════════════════════════════════════
SUMMARY
════════════════════════════════════════════════════════════════════════════════
Overall Performance:
  Average fastIsEqual time:    0.000172 ms
  Average Lodash isEqual time: 0.002013 ms
  fastIsEqual is 11.73x faster on average

Win Rate:
  fastIsEqual wins: 46/49 (93.9%)
  Lodash wins:      3/49 (6.1%)

🏆 Top 10 Best Performance Gains:
  1. Large Set (100 items): 55.84x faster
  2. Map vs Set: 26.52x faster
  3. Large Map (50 entries): 24.32x faster
  4. Map with primitives: 16.09x faster
  5. Map (unequal): 15.29x faster
  6. Large TypedArray (1000): 13.95x faster
  7. ArrayBuffer (small): 13.74x faster
  8. Empty Set: 11.96x faster
  9. Empty Map: 11.84x faster
  10. Set of strings: 11.51x faster

⚠️  Cases where Lodash performed better:
  1. String vs Number: 0.95x
  2. Large Numbers: 0.99x
  3. Boolean vs Number: 0.99x

════════════════════════════════════════════════════════════════════════════════
✨  Done in 108.11s.

License

MIT

MIT License

Copyright (c) 2025 Jairaj Jangle

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

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