Javascript: How do I check if a var is null or hasn't been set?? - GoFuckYourself.com

Zester · 12-08-2005, 03:02 AM

sounds simple doesn't it? this is fucking driving crazy

lets say "myvar" was never mentioned in the code anywhere.
the following gives an error message "myvar is undefined" which I want to avoid:

Code:

if ( myvar = =  undefined )
{
   // do nothing
}

I also tried:

Code:

if ( myvar = =  null )
if ( myvar = =   0 )
if ( myvar = =   "" )
if ( myvar = =   '' )

of course I don't use spaces between the two "=" but that's just for displaying

J.P. · 12-08-2005, 03:53 AM

try this:

Code:

if (typeof myvar = = "undefined") {
   // do something - or nothing :)
}

this should solve your problem...

of course, drop the space between = and =

emthree · 12-08-2005, 06:09 AM

You must nul your var

Zester · 12-08-2005, 09:55 AM

Quote:

Originally Posted by J.P.

try this:

Code:

if (typeof myvar = = "undefined") {
   // do something - or nothing :)
}

this should solve your problem...

of course, drop the space between = and =

thanks mate

12-08-2005, 03:02 AM	#1
Zester Confirmed User Industry Role: Join Date: Jul 2003 Posts: 5,344	Javascript: How do I check if a var is null or hasn't been set?? sounds simple doesn't it? this is fucking driving crazy lets say "myvar" was never mentioned in the code anywhere. the following gives an error message "myvar is undefined" which I want to avoid: Code: if ( myvar = = undefined ) { // do nothing } I also tried: Code: if ( myvar = = null ) if ( myvar = = 0 ) if ( myvar = = "" ) if ( myvar = = '' ) of course I don't use spaces between the two "=" but that's just for displaying __________________ * Mainstream ? $65 per sale * new male contraception

12-08-2005, 03:53 AM	#2
J.P. Confirmed User Join Date: Jun 2004 Posts: 689	try this: Code: if (typeof myvar = = "undefined") { // do something - or nothing :) } this should solve your problem... of course, drop the space between = and = __________________ Webmasters! Looking for new affiliate programs to promote? Affiliate Program Search <-- Search for programs with FHGs, RSS feed, specific niche sponsors, ... Last edited by J.P.; 12-08-2005 at 03:56 AM..

12-08-2005, 06:09 AM	#3
emthree Dialer Kingpin Join Date: Jun 2003 Location: New York Posts: 10,816	You must nul your var __________________ • Sell Patches & Pills •