<!DOCTYPE html>
<html>
<body>
<h1>JavaScript 数组</h1>
<p>使用数字索引（从 0 开始）访问 JavaScript 数组元素。</p>
<p id="demo"></p>
<script>
var cars = ["Audi", "BMW", "porsche"];
cars[0] = "Volvo";
document.getElementById("demo").innerHTML = cars;
</script>
</body>
</html>