please dont rip this site

JavaScript: The Definitive Guide

Previous Chapter 21
JavaScript Reference
Next
 

isNaN() Function

Name

isNaN() Function---check for Not-a-Number

Availability

Navigator 3.0; Unix platforms in Navigator 2.0; implemented but nonfunctional in Internet Explorer 3.0

Synopsis

isNaN(x)

Arguments

x

The value to be tested.

Returns

true if x is the reserved value NaN (not-a-number); false if x is a legal number, string, or any other type.

Description

isNaN() tests its argument to determine whether it is the reserved value NaN, which represents an illegal number (such as the result of division by zero). This function is required, because comparing a NaN with any value, including itself, always returns false, so it is not possible to test for NaN with the == operator.

The NaN value is not implmemented in Internet Explorer 3.0, so isNaN() always returns false on that platform.

A common use of isNaN() is to test the result of parseFloat() and parseInt() to determine if they represent legal numbers. You can also use it to check for arithmetic errors, such as division by zero.

See Also

"Number.NaN", "parseFloat()", "parseInt()"


Previous Home Next
Image.width Book Index java

HTML: The Definitive Guide CGI Programming JavaScript: The Definitive Guide Programming Perl WebMaster in a Nutshell

file: /Techref/language/java/script/definitive/refp_176.htm, 5KB, , updated: 2019/10/14 15:00, local time: 2024/11/8 10:11,
TOP NEW HELP FIND: 
3.149.239.65:LOG IN
©2024 PLEASE DON'T RIP! THIS SITE CLOSES OCT 28, 2024 SO LONG AND THANKS FOR ALL THE FISH!

 ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF="http://linistepper.com/Techref/language/java/script/definitive/refp_176.htm"> [Chapter 21] Reference: isNaN()</A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type a nice message (short messages are blocked as spam) in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?