[void()]

<textarea></textarea>
<hr>
<button>click me</button>
<hr>
<div class="boll"></div>

<style>
.boll{
  position: absolute;
  left: 10px;
  top: 120px;
  width: 10px;
  height: 10px;
  background-color: #333;
  border-radius: 50%;
  transition: left .5s, top .5s;
}
</style>

<script>
let textBlock = document.querySelector('textarea');
textBlock.addEventListener('keyup', function(e){
        alert(e.keyCode + ' : ' + e.key);
});

let btn = document.querySelector('button');
btn.addEventListener('mouseup', function(e){
if(e.ctrlKey){
        this.style.backgroundColor = 'red';
}
});

let boll = document.querySelector('.boll');
document.addEventListener('click', function(e){
	boll.style.left = e.clientX + 'px';
  boll.style.top = e.clientY + 'px';
});
</script>