1let test = document.getElementById("test");
2
3test.addEventListener("mouseover", function( event ) {
4  alert("mouse over test!")
5  , false);

1let test = document.getElementById("test");
2  
3// This handler will be executed only once when the cursor
4// moves over the unordered list
5test.addEventListener("mouseenter", function( event ) {   
6  // highlight the mouseenter target
7  event.target.style.color = "purple";
8
9  // reset the color after a short delay
10  setTimeout(function() {
11    event.target.style.color = "";
12  }, 500);
13}, false);