js window dimensions

const window {
  width: window.innerWidth,
  height: window.innerHeight
}// better than using window.innerWidth / window.innerHeight 
// because of scrollbars
const client = {
      width: document.documentElement.clientWidth,
      height: document.documentElement.clientHeight
}<p id="demo"></p>

<script>
document.getElementById("demo").innerHTML = 
"Screen width is " + screen.width;
</script>