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

<h2>JavaScript 变量</h2>

<p>在本例中,x 被定义为变量。然后 x 被赋值 7:</p>

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

<script>
var x;
x = 7;
document.getElementById("demo").innerHTML = x;
</script>

</body>
</html>
运行结果: