JS DOM Animation

<!DOCTYPE html>
<html>
<style>
#container {
  width: 400px;
  height: 100px;
  position: relative;
  background: yellow;
}
#animate {
  width: 50px;
  height: 50px;
  position: absolute;
  background-color: red;
  border-radius:50%;
  margin-top:20px;
}
</style>
<body>

<p><button onclick="myMove()">Click Me</button></p> 

<div id ="container">
  <div id ="animate"></div>
</div>

<script>
var id = null;
function myMove() {
  var elem = document.getElementById("animate");   
  var pos = 0;
  clearInterval(id);
  id = setInterval(frame, 5);
  function frame() {
    if (pos == 350) {
      clearInterval(id);
    } else {
      pos++; 
      elem.style.left = pos + "px"; 
    }
  }
}
</script>

</body>
</html>