代码如下：
<!DOCTYPE html>
<html>
<head>
<style>
div#circle
{
width:100px;
height:100px;
overflow:hidden;
transform-origin:100% 100%;
}
#fan{
width:0; height:0; border-radius:100px; border-width:100px; border-style:solid; border-color:red transparent transparent transparent; line-height:99em; overflow:hidden; cursor:pointer;
transform:rotate(-45deg);
}
</style>
</head>
<body>
<div style="width:200px; height:200px; background-color:green; margin:30px">
<div id="circle">
<div id="fan">Hello World</div>
</div></div>
<button onClick="rotate()">旋转</button>
<script>
var deg=0;
function rotate(){
console.log(222)
deg=deg+90;
var circle=document.getElementById("circle");
circle.style.transform ="rotate("+deg+"deg)";
}
</script>
</body>
</html>
