The best way to interpolate 2D angles

betterAngleLerp.js

//note: degrees only

const lerp = (start,end,amt) => start+(end-start)*amt
const clamp = (num, min, max) => Math.min(Math.max(num, min), max);
const repeat = (t, m) => clamp(t - Math.floor(t / m) * m, 0, m);

function lerpTheta(a, b, t) {
  const dt = repeat(b - a, 360);
  return lerp(a, a + (dt > 180 ? dt - 360 : dt), t);
}

//

why use "(1-t)a+tb" this "a+(b-a)*t" is much easier to read and write.

gotcha, I have updated it

The updated code is incorrect: amt+(end-start)*amt should be start+(end-start)*amt

How did I miss this?! Thanks so much for catching this.