html运行实例（js_datatypes_undefined

代码示例：（标识：js_datatypes_undefined_2）

<!DOCTYPE html>
<html>
<body>

<h1>JavaScript</h1>

<p>如果将值设置为 <b>undefined</b>，则可以清空变量。</p>

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

<script>
let car = "Volvo";
car = undefined;

document.getElementById("demo").innerHTML = car + "<br>" + typeof car;
</script>

</body>
</html>