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

<p>典型的算术运算会操作两个数(或表达式)并返回一个新的数。</p>

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

<script>
var a = 7;
var b = 8;
var x = a + b;
document.getElementById("demo").innerHTML = x;
</script>

</body>
</html>
运行结果: