@justwant/bezier

Cubic Bézier curves for easing. Core minimal (no presets), presets in subpaths by usage domain.

Installation

bun add @justwant/bezier

Usage

Core (@justwant/bezier)

Custom params only — no presets in core.

import { createBezierCurve } from "@justwant/bezier";

const curve = createBezierCurve({ p1x: 0.42, p1y: 0, p2x: 0.58, p2y: 1 });
curve.at(0);   // 0
curve.at(1);   // 1
curve.at(0.5); // ~0.5 (y clamped to [0,1])

Classic (@justwant/bezier/classic)

CSS-like presets: linear, ease-in, ease-out, ease-in-out.

import { linear, easeIn, easeOut, easeInOut } from "@justwant/bezier/classic";

linear.at(0.5);    // 0.5
easeIn.at(0.5);   // < 0.5 (slow at start)
easeOut.at(0.5);  // > 0.5 (slow at end)
easeInOut.at(0.5); // ≈ 0.5

Feature (@justwant/bezier/feature)

Rollout/adoption curves for feature flags (used by @justwant/flag for diffusionBezier).

import { slowRollout, fastRollout, gradual } from "@justwant/bezier/feature";

Animation (@justwant/bezier/animation)

Design/UI easing presets.

import { easeIn, easeOut, easeInOut } from "@justwant/bezier/animation";

API

| Export | Description | |--------|-------------| | createBezierCurve({ p1x, p1y, p2x, p2y }) | Create curve from control points (all ∈ [0,1]) | | BezierCurve.at(t) | Evaluate at t ∈ [0,1], returns y ∈ [0,1] (clamped) | | InvalidBezierParamsError | Thrown when params outside [0,1] |

Subpaths

| Path | Presets | |------|---------| | @justwant/bezier | createBezierCurve, types, errors | | @justwant/bezier/classic | linear, easeIn, easeOut, easeInOut | | @justwant/bezier/feature | slowRollout, fastRollout, gradual | | @justwant/bezier/animation | easeIn, easeOut, easeInOut | | @justwant/bezier/errors | BezierError, InvalidBezierParamsError |

License

MIT