<html>
<head>
</head>
<body>
<div id="box">
</div>
<script>
var head = document.getElementsByTagName('head')[0];
var box = document.getElementById('box');
if (false){
var style = box.style;
style.width = '200px';
style.height = '200px';
style.backgroundColor = '#eed';
}
if (false){
box.style.cssText = 'width:200px;height:200px;background-color:#eed';
}
if (true){
var style = document.createElement('style');
head.appendChild(style);
var sheet = style.sheet;
sheet.insertRule('#box{width:200px;height:200px;background-color:#eed}',
sheet.cssRules.length);
console.log(sheet.cssRules.length);
}
</script>
</body>
</html>