Definition and Usage
定义与用法

Syntax
语法

NaN

Tips and Notes
提示：

Tip: Use the isNan() function to test a value to see if it is NaN.
提示：可以用isNan()方法测试一个值是否为NaN

Example
实例

In this example we will test two strings and find out if one of them is NaN:
在下面的例子中，我们将对两个值进行测试，找出非数字的值：

<script type="text/javascript">

var test1="300"
var test2="你好！"

document.write(Number(test1)+ "<br />")
document.write(Number(test2)+ "<br />")

document.write(isNaN(test1)+ "<br />")
document.write(isNaN(test2))

</script>

The output of the code above will be:
输出结果为：

300
NaN
false
true

Try-It-Yourself Demos
互动演练

NaN
How to use NaN to evaluate a number.
如何应用NaN来判断数字

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