示例：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<script>
window.onload = function(){
var current = 0;
document.getElementById('target').onclick = function(){
current = (current+90)%360;
this.style.transform = 'rotate('+current+'deg)';
}
};
</script>
</head>
<body>
<img id ="target" src="1.jpg" alt="">
</body>
</html>
