Angle math functions in JavaScript

angle.js

/**
 * `n` modulo `d` (because JavaScript `%` remainder operator is useless when `n < 0`)
 * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Remainder
 * @param {number} n
 * @param {number} d
 */
export function mod(n, d) {
  return ((n % d) + d) % d
}

/**
 * Smallest equivalent angle, from -π to +π
 * @param {number} angle
 */
export function equivalentAngle(angle) {
  return mod(angle + Math.PI, Math.PI * 2) - Math.PI
}

/**
 * Same as `to`, but closest to `from` (can be used to prevent over-rotation)
 * @param {number} from
 * @param {number} to
 */
export function closestAngle(from, to) {
  return from + equivalentAngle(to - from)
}