requestAnimationFrame-basic-example.js

let starttime;
 
function moveit(timestamp, x, duration){
    const runtime = timestamp - starttime;
    let progress = Math.min((runtime / duration), 1);
    console.log(x * progress);
    if (runtime < duration) requestAnimationFrame(timestamp => moveit(timestamp, x, duration));
}
 
requestAnimationFrame(timestamp => {
    starttime = timestamp;
    moveit(timestamp, 400, 2000);
});