I'm getting a runtime error when I try to run a piece of JavaScript. The line that is causing the problem is the first line of an if statement:

if(QueryString != undefined && QueryString["date"] != undefined) {

The error states that undefined is undefined. Note this only happens in some browsers!

From some research I have found that the undefined keyword only works for some browsers has anyone got any more info on this e.g. which browsers it will work for? Can anyone come up with a workaround so that I can check if variables are undefined.

Help appreciated.

DJ