<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>随机选择器</title>
</head>
<style>
*{
margin: 0px;
padding: 0px;
user-select: none;
}
#show{
480px;
height: 320px;
background: rgb(255, 127, 39);
margin: 0px auto;
margin-top: 100px;
overflow: hidden;
border-radius: 20px;
}
#uname{
320px;
height: 80px;
background: blue;
color: #FFF;
font-size: 30px;
text-align: center;
margin: 0 auto;
line-height: 80px;
margin-top: 60px;
border-radius: 10px;
margin-top: 80px;
}
#btn{
200px;
height:60px;
border: none;
background: #FFF;
border-radius: 10px;
margin: 0 auto;
margin-top: 30px;
display: block;
color: blue;
font-size: 40px;
text-align: center;
}
#btn:hover{
cursor: pointer;
}
</style>
<body>
<div id="show">
<div id="uname">答案</div>
<div id="btn">开始</div>
</div>
<script>
var uname = document.getElementById("uname");
var btn = document.getElementById("btn");
var select = ["A", "B", "C", "D"];
var start;
var rand = function(m, n) {
var num = Math.floor(Math.random()*(n - m) + m);
return num;
}
btn.onclick = function() {
if(this.innerHTML == "开始") {
/*解决定时器叠加*/
if(start) {
return;
}
start = setInterval(function() {
var index = rand(0, select.length - 1);
uname.innerHTML = select[index];
},50);
this.innerHTML = "停止";
}else{
clearInterval(start);
start = "";
this.innerHTML = "开始";
}
}
</script>
</body>
</html>
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