test.html

<div style="width: 200px; height: 10px; background: red"></div>
<script>

  var div = document.querySelector("div");

  var x = 0;
  var sign = 1;

  // Comment this line out to test with native rAF
  // window.requestAnimationFrame = c => setTimeout(c, 16);

  function step() {
    x += sign * 1;
    if (x == 100 || x == 0) {
      sign = -sign;
    }
    div.style.transform = `translateX(${x}px)`;
    requestAnimationFrame(step);
  }

  step();

</script>