Javascript - animate()

animate.js

export function animate(cb, time) {
  return new Promise((resolve, reject) => {
    const startTime = performance.now();
    const endTime = startTime + time;

    function run() {
      const currentTime = performance.now();
      const deltaTime = currentTime - startTime;

      const pctDone = deltaTime / time;
      if (currentTime < endTime) {
        if (cb(pctDone) !== false) {
          window.requestAnimationFrame(run);
        } else {
          reject();
        }
      } else {
        cb(1)
        resolve();
      }
    }

    window.requestAnimationFrame(run)
  });
}