随机切换图片技术

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>random</title>
</head>
<body>
<img src="" id="imgid" alt="">
<script>
    function selectImg(){
        arr = ['a.jpg','b.jpg','c.jpg','d.jpg','e.jpg'];
        key = Math.floor(Math.random()*arr.length);
        val = arr[key];
        imgobj = document.getElementById("imgid");
        imgobj.src = 'img/'+val;
    }
    setInterval(selectImg,100);
</script>
</body>
</html>