JSFiddle - React, Tailwind, and code Playground

HTML

<div id = 'test'></div>

CSS

#test {
  width: 50px;
  height: 50px;
  background: red;
  position: relative;
}

JavaScript

var a = $('#test');
var x = 0;
var n = -5
function animate() {

  if (!x || x == 300) {
    
    n = -n;
  }
  x = x + n;
  a.offset({left:x});
}  
  setInterval(animate,10);