4.7 循环广告条

数组存图片，切换属性；
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="refresh" content="20">
    <link rel="stylesheet" href="myCSS.css">
    <script>
        var index = 0;
        function start() {
            var images = ["src/test_on.png","src/test_off.png"];
            var myImage = document.getElementById("myImageID");
            myImage.src = images[index % 2];
            this.index++;
            setTimeout(start,2000);
        }
        window.onload = start;
    </script>
</head>
<body>
<img id="myImageID" src="src/test_on.png">
</body>
</html>