animate

animate.js

let frameCounter = 0;

function countFrames () { 
    frameCounter++;
    requestAnimationFrame(countFrames);
}

requestAnimationFrame(countFrames);

function* animate (from, to, numFrames) {
    let lastFrameCount = frameCounter;

    const delta = (to - from) / numFrames;
    let current = from;

    while (numFrames > 0) {
        const framesPassed = frameCounter - lastFrameCount;
        numFrames -= framesPassed;
        lastFrameCount = frameCounter;
        current += delta * framesPassed;
        yield current;
    }

    if (current !== to) yield to;
}