JavaScript NaN Property: Number Object


The NaN property of number object represents a value that is not a number. JavaScript prints the value as NaN.


Implemented in JavaScript 1.1




The following web document demonstrates how the NaN() property can be used.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<title>JavaScript Number object - NAN property example</title>
<h1 style="color: red">JavaScript Number object : NAN property</h1>
<hr />
<script type="text/javascript">
//This is done to make the following JavaScript code compatible to XHTML. <![CDATA[
if(123 == Number.NaN)
document.write("This is not a number.... " + "<br>");
document.write("It is a number...." + "<br>");
var week = 17;
if ( week < 1 || week > 7)
week = Number.NaN;

View the example in the browser

Supported Browser

Internet Explorer 7 Firefox 3.6 Google Chrome 7 Safari 5.0.1 Opera 10
Yes Yes Yes Yes Yes

See also:

JavaScript Core objects, methods, properties.

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Next: JavaScript NEGATIVE_INFINITY Property

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JavaScript: Tips of the Day

How do I redirect to another webpage?

window.location.replace(...) is better than using window.location.href, because replace() does not keep the originating page in the session history, meaning the user won't get stuck in a never-ending back-button fiasco.

If you want to simulate someone clicking on a link, use location.href

If you want to simulate an HTTP redirect, use location.replace.

// similar behavior as an HTTP redirect

// similar behavior as clicking on a link
window.location.href = "http://stackoverflow.com";

Ref: https://bit.ly/37JdWH8