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

<h1>JavaScript 变量</h1>

<p>在本例中,x、y 以及 z 都是变量。</p>

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

<script>
var x = 7;
var y = 8;
var z = x + y;
document.getElementById("demo").innerHTML =
"z 的值是:" + z;
</script>

</body>
</html>
运行结果: