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

<h2>JavaScript 数据类型</h2>

<p>空的字符串变量既有值也有类型。</p>

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

<script>
var car = "";
document.getElementById("demo").innerHTML =
"其值是:" +
car + "<br>" +
"类型是:" + typeof car;
</script>

</body>
</html>
运行结果: