<!DOCTYPE html>
<html>
<body>

<p>This example demonstrates how to assign an "onmouseenter" and "onmouseleave" event to a h1 element.</p>

<h1 id="demo" onmouseenter="mouseEnter()" onmouseleave="mouseLeave()">Mouse over me</h1>

<script>
function mouseEnter() {
    document.getElementById("demo").style.color = "red";
}

function mouseLeave() {
    document.getElementById("demo").style.color = "black";
}
</script>

</body>
</html>