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

[Zester]

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:

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

I also tried:

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.]

try this:

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

this should solve your problem...

of course, drop the space between = and =

[emthree]

You must nul your var

[Zester]

Originally Posted by J.P.

try this:

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

this should solve your problem...

of course, drop the space between = and =

thanks mate