addEventListener
HTML
<div id="foo">
this my test
</div>JavaScript
var foo = document.getElementById('foo');
foo.addEventListener('mouseover', mousedown1);
foo.addEventListener('mouseleave', mouseleave1);
function mousedown1() {
console.log('red');
this.style.border = "1px solid red";
}
function mouseleave1() {
console.log('green');
this.style.border = "1px solid green";
}