<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
#div1 {
width: 100px;
height: 100px;
background: red;
}
</style>
<script type="text/javascript">
function toGreen()
{
document.getElementById('div1').style.width='200px';document.getElementById('div1').style.height='200px';document.getElementById('div1').style.background='green';
}
function toRed() {
document.getElementById('div1').style.width='100px';document.getElementById('div1').style.height='100px';document.getElementById('div1').style.background='red';
}
</script>
</head>
<body>
<div id="div1" onmouseover="toGreen()" onmouseout="toRed()">
</div>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
#div1 {
width: 100px;
height: 100px;
background: red;
}
</style>
</head>
<body>
<div id="div1" onmouseover="document.getElementById('div1').style.width='200px';document.getElementById('div1').style.height='200px';document.getElementById('div1').style.background='green';" onmouseout="document.getElementById('div1').style.width='100px';document.getElementById('div1').style.height='100px';document.getElementById('div1').style.background='red';">
</div>
</body>
</html>