Easing functions in TypeScript.

easings.ts

const EASINGS: Record<string, (t: number) => number> = {
  linear: (t) => t,
  easeInQuad: (t) => t * t,
  easeOutQuad: (t) => t * (2 - t),
  easeInOutQuad: (t) => (t < 0.5 ? 2 * t * t : -1 + (4 - 2 * t) * t),
  easeInCubic: (t) => t * t * t,
  easeOutCubic: (t) => --t * t * t + 1,
  easeInOutCubic: (t) =>
    t < 0.5 ? 4 * t * t * t : (t - 1) * (2 * t - 2) * (2 * t - 2) + 1,
  easeInQuart: (t) => t * t * t * t,
  easeOutQuart: (t) => 1 - --t * t * t * t,
  easeInOutQuart: (t) =>
    t < 0.5 ? 8 * t * t * t * t : 1 - 8 * --t * t * t * t,
  easeInQuint: (t) => t * t * t * t * t,
  easeOutQuint: (t) => 1 + --t * t * t * t * t,
  easeInOutQuint: (t) =>
    t < 0.5 ? 16 * t * t * t * t * t : 1 + 16 * --t * t * t * t * t,
  easeInSine: (t) => 1 - Math.cos((t * Math.PI) / 2),
  easeOutSine: (t) => Math.sin((t * Math.PI) / 2),
  easeInOutSine: (t) => -(Math.cos(Math.PI * t) - 1) / 2,
  easeInExpo: (t) => (t <= 0 ? 0 : Math.pow(2, 10 * t - 10)),
  easeOutExpo: (t) => (t >= 1 ? 1 : 1 - Math.pow(2, -10 * t)),
  easeInOutExpo: (t) =>
    t <= 0
      ? 0
      : t >= 1
      ? 1
      : t < 0.5
      ? Math.pow(2, 20 * t - 10) / 2
      : (2 - Math.pow(2, -20 * t + 10)) / 2,
}