W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
#myDIV {
  background-color: coral;
  border: 1px solid;
  padding: 50px;
  color: white;
}
</style>
</head>
<body>

<p>This example demonstrates a solution that will work for all browsers.</p>

<div id="myDIV">This div element has an onmousemove event handler that displays a random number every time you move your mouse inside this orange field.
  <p>Click the button to remove the DIV's event handler.</p>
  <button onclick="removeHandler()" id="myBtn">Try it</button>
</div>

function myFunction() {
  document.getElementById("demo").innerHTML = Math.random();
}

function removeHandler() {
  if (x.removeEventListener) {
    x.removeEventListener("mousemove", myFunction);
  } else if (x.detachEvent) {
    x.detachEvent("onmousemove", myFunction);
  }
}
</script>

</body>
</html>

​x
 
<!DOCTYPE html><html><head><style>#myDIV {  background-color: coral;  border: 1px solid;  padding: 50px;  color: white;}</style></head><body>​<p>This example demonstrates a solution that will work for all browsers.</p>​<div id="myDIV">This div element has an onmousemove event handler that displays a random number every time you move your mouse inside this orange field.  <p>Click the button to remove the DIV's event handler.</p>  <button onclick="removeHandler()" id="myBtn">Try it</button></div>​<p id="demo"></p>​<script>var x = document.getElementById("myDIV");if (x.addEventListener) {  x.addEventListener("mousemove", myFunction);} else if (x.attachEvent) {  x.attachEvent("onmousemove", myFunction);}​function myFunction() {  document.getElementById("demo").innerHTML = Math.random();}​function removeHandler() {  if (x.removeEventListener) {    x.removeEventListener("mousemove", myFunction);  } else if (x.detachEvent) {    x.detachEvent("onmousemove", myFunction);  }}</script>​