<html>
<body>
<p>点击按钮按降序循环数组。</p>
<button onclick="myFunction()">点我</button>
<p id="demo"></p>
<script>
function myFunction() {
var cars = ["BMW", "Volvo", "Saab", "Ford"];
var text = "";
var len = cars.length;
while (len--) {
text += cars[len] + "<br>";
}
document.getElementById("demo").innerHTML = text;
}
</script>
</body>
</html>