@zakkster/lite-ease

🎢 What is lite-ease?

@zakkster/lite-ease is the complete set of Robert Penner easing equations as individual, tree-shakeable ES module exports.

It gives you:

• 🎢 30 easing functions (10 families × 3 variants)
• 🧮 Pure math: (t: number) => number where t ∈ [0, 1]
• 🔗 Composable: lerp(a, b, easeOutBounce(t))
• 🛡️ clamp01() wrapper for Back/Elastic overshoot
• 🔄 reverse(ease) creates the inverse curve
• 📖 easings lookup map for string-based access
• 0️⃣ Zero dependencies, pure math, no allocation
• 🪶 < 1 KB minified (entire library)

Part of the @zakkster/lite-* ecosystem — micro-libraries built for deterministic, cache-friendly game development.

🚀 Install

npm i @zakkster/lite-ease

🕹️ Quick Start

import { easeOutBounce, easeInOutElastic, clamp01, reverse } from '@zakkster/lite-ease';
import { lerp } from '@zakkster/lite-lerp';

// Compose with any interpolation
const y = lerp(startY, endY, easeOutBounce(t));

// Clamp overshoot (Back/Elastic can exceed 1.0)
const safe = lerp(0, 255, clamp01(easeOutBack(t)));

// Create inverse curve
const myEaseOut = reverse(easeInCubic);

// String-based lookup (useful for configs/JSON)
import { easings } from '@zakkster/lite-ease';
const ease = easings[config.easing]; // 'easeOutBounce' → function

📊 Comparison

| Library | Size | Functions | Format | Install | |---------|------|-----------|--------|---------| | bezier-easing | ~3 KB | Custom curves | Class | npm i bezier-easing | | eases | ~2 KB | 31 | CommonJS | npm i eases | | lite-ease | < 1 KB | 31 + helpers | ESM, tree-shakeable | npm i @zakkster/lite-ease |

⚙️ API

10 Families × 3 Variants

| Family | easeIn | easeOut | easeInOut | |--------|--------|---------|-----------| | Sine | easeInSine | easeOutSine | easeInOutSine | | Quad | easeInQuad | easeOutQuad | easeInOutQuad | | Cubic | easeInCubic | easeOutCubic | easeInOutCubic | | Quart | easeInQuart | easeOutQuart | easeInOutQuart | | Quint | easeInQuint | easeOutQuint | easeInOutQuint | | Expo | easeInExpo | easeOutExpo | easeInOutExpo | | Circ | easeInCirc | easeOutCirc | easeInOutCirc | | Back | easeInBack | easeOutBack | easeInOutBack | | Elastic | easeInElastic | easeOutElastic | easeInOutElastic | | Bounce | easeInBounce | easeOutBounce | easeInOutBounce |

Helpers

• linear(t) — Identity function
• clamp01(t) — Clamp to [0, 1]. Back/Elastic overshoot safely.
• reverse(ease) — Create the inverse: reverse(easeIn) ≈ easeOut
• easings — Record<string, Function> for dynamic lookup

🧪 Benchmark

31 easing functions, 1M calls each:
  All functions: < 0.01ms per call (pure arithmetic)
  No allocation, no branching (except Bounce/Elastic)
  Tree-shakeable: unused functions are eliminated by bundlers

📦 TypeScript

Full declarations included in lite-ease.d.ts.

📚 LLM-Friendly Documentation

See llms.txt for AI-optimized metadata and usage examples.

License

MIT