@billdaddy/mathkit

mathkit

Tiny, type-safe scalar math utilities — clamp, lerp, remap, smoothstep, precise round, wrap, gcd/lcm, and more. Zero dependencies.

Math gives you min, max, and round — but every UI, chart, game, and animation also needs clamp, lerp, a remap between ranges, and a round that doesn't trip on 1.005. mathkit is that missing scalar toolbox, fully typed and tree-shakeable.

import { clamp, lerp, remap } from "@billdaddy/mathkit";

clamp(volume, 0, 1);                 // keep in range
lerp(start, end, t);                 // animate
remap(scrollY, 0, 800, 1, 0.4);      // map scroll → opacity

Why mathkit?

• The everyday helpers. clamp, clamp01, lerp, inverseLerp, remap, smoothstep, smootherstep.
• Rounding done right. round(1.005, 2) === 1.01 (the naive * 100 trick gives 1); plus roundTo for nearest-multiple snapping.
• Float-safe comparisons. isClose uses combined absolute + relative tolerance, so 0.1 + 0.2 ≈ 0.3 and large numbers compare sanely.
• Angles & wrapping. degToRad/radToDeg and a wrap that handles negatives and arbitrary ranges (great for angles and looping indices).
• Number theory. gcd, lcm.
• Tree-shakeable. sideEffects: false, ESM + CJS, zero dependencies.

Install

npm install @billdaddy/mathkit
# or: pnpm add @billdaddy/mathkit  /  yarn add @billdaddy/mathkit  /  bun add @billdaddy/mathkit

Interpolation

import { clamp, clamp01, lerp, inverseLerp, remap, smoothstep } from "@billdaddy/mathkit";

clamp(15, 0, 10);          // 10   (swapped bounds are tolerated)
clamp01(1.5);              // 1
lerp(0, 100, 0.25);        // 25   (t is not clamped)
inverseLerp(0, 100, 25);   // 0.25
remap(5, 0, 10, 0, 100);   // 50
smoothstep(0, 1, 0.25);    // 0.15625 (eased, clamped)

Rounding & comparison

import { round, roundTo, isClose } from "@billdaddy/mathkit";

round(1.005, 2);     // 1.01
round(1234.5678, -2); // 1200
roundTo(0.27, 0.05); // 0.25
isClose(0.1 + 0.2, 0.3); // true
isClose(1, 1.05, 0.1);   // true (custom tolerance)

Angles, wrapping, number theory

import { degToRad, radToDeg, wrap, gcd, lcm } from "@billdaddy/mathkit";

degToRad(180);        // 3.14159…
wrap(370, 0, 360);    // 10
wrap(-30, 0, 360);    // 330
gcd(12, 18);          // 6
lcm(4, 6);            // 12

Pairs well with

Need	Use
Reduce arrays (sum, mean, minBy…)	@billdaddy/arraykit
Human-format numbers (1.2K, bytes)	humankit

Contributors

This project follows the all-contributors specification. Contributions of any kind are welcome — code, docs, bug reports, ideas, reviews! See the emoji key for how each contribution is recognized, and open a PR or issue to get involved.

Thanks goes to these wonderful people:

Tung Tran

License

MIT Tung Tran