​x
 
<!DOCTYPE html>
<html>
<body>
​
<h1>JavaScript 数字</h1>
​
<p>假如您在数学运算中使用了 NaN，则结果也将是 NaN：</p>
​
<p id="demo"></p>
​
<script>
var x = NaN;
var y = 5;
document.getElementById("demo").innerHTML = x + y;
</script>
​
</body>
</html>
​
​