<style>
.style1{
width: 200px;
height: 200px;
border: solid 1px red;
}
.style2{
background-color: #00b8e9;
position: absolute;
right: 10px;
}
</style>
<body>
<div class="style1" id="div1">div1</div>
<button id="change">移位</button>
</body>
<script> var change = document.getElementById("change"); change.addEventListener("click", function () { var div=document.getElementById("div1"); div.className += " style2";
// className可以设置或返回元素的 class 属性
// div.style.width = "500px";// div.style.backgroundColor = "red"; div.style.cssText="font-size=50px;color=red"/*一定要加上分号*/ });</script>