代码示例:(标识:eg_js_scope_window)
<!DOCTYPE html>
<html>
<body>

<h1>JavaScript 作用域</h1>

<p>在 HTML 中,通过 <b>var</b> 定义的全局变量,会成为 window 变量。</p>

<p id="demo"></p>

<script>
var carName = "porsche";

// code here can use window.carName
document.getElementById("demo").innerHTML = "我可以显示 " + window.carName;
</script>

</body>
</html>
运行结果: