<!DOCTYPE html>
<html>
<body>
<h1>JavaScript 变量</h1>
<p>相加 3 + 5 + "8" 的结果是：</p>
<p id="demo"></p>
<script>
var x = 3 + 5 + "8"
document.getElementById("demo").innerHTML = x;
</script>
</body>
</html>