how to access a hover in the dom code example

Example 1: addeventlistener hover js

let test = document.getElementById("test");

test.addEventListener("mouseover", function( event ) {
  alert("mouse over test!")
  , false);

Example 2: hover con js

// Creamos el evento mouseover para cada imagen
	imagenes[i].addEventListener("mouseover", function(e){
		document.getElementById("mostrar").style.backgroundImage="url('"+e.target.currentSrc+"')";
	});
 
// Creamos el evento mouseout para cada imagen
imagenes[i].addEventListener("mouseout", function(e){
  document.getElementById("mostrar").style.backgroundImage="";
});