var box = document.getElementById('box'), boxPos = 10, boxVelocity = 0.08, limit = 300, lastFrameTimeMs = 0, maxFPS = 60, delta = 0, timestep = 1000 / 60; function update(delta) { boxPos += boxVelocity * delta; // Switch directions if we go too far if (boxPos >= limit || boxPos <= 0) boxVelocity = -boxVelocity; } function draw() { box.style.left = boxPos + 'px'; } function mainLoop(timestamp) { // Throttle the frame rate. if (timestamp < lastFrameTimeMs + (1000 / maxFPS)) { requestAnimationFrame(mainLoop); return; } delta += timestamp - lastFrameTimeMs; lastFrameTimeMs = timestamp; while (delta >= timestep) { update(timestep); delta -= timestep; } draw(); requestAnimationFrame(mainLoop); } requestAnimationFrame(mainLoop);
<div id="box" style="position: absolute; top: 10px; left: 10px; height: 50px; width: 50px; background-color: red;"></div>