1.点击切换颜色:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
.my{
background-color: red;
width: 100px;
height: 100px;
}
</style>
</head>
<body>
<div class = "my"></div>
<script>
var flag = true;
var oMy = document.getElementsByClassName("my")[0]
oMy.onclick = function(){
if (flag){
oMy.style.backgroundColor = 'green';
flag = false;
}else{
oMy.style.backgroundColor = 'red';
flag = true;
}
}
</script>
</body>
</html>