1、class——获取样式名or长度
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<script>function(){
var oBtn = document.getElementById('btn1');
oBtn.onclick = function(){
//alert(this.className);
//alert(this.classList.length);
//alert(this.tagName);
//alert(this.classList[1]);</script>
</head>
<body>
<input id="btn1" class="add active box" type="button" value="按钮"
</body>
</html>
2、class——添加删除
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<script>function(){
var oBtn = document.getElementById('btn1');
oBtn.onclick = function(){
//this.classList.add("active");//添加一个样式
//this.classList.remove("active");//删除一个样式
//alert(this.classList.contains("add1"));//判断是否包含一个样式
this.classList.toggle("active");//添加删除一个样式状态切换</script>
</head>
<body>
<input id="btn1" class="add active box active active active" type="button" value="按钮"
</body>
</html>
