Question

I don’t have an access to IE6 right now, so, I am asking here.

If I have a comparison such as:

// imagine App being declared as an obj somewhere...
if (App.errorLog === undefined) {
    App.errorLog = [];
}

Would that code throw an error in IE6 if the property was never declared or defined anywhere? It seems to work fine in other browsers even in IE7. I just think that I had some problems with IE6 while a back and used typeof to solve those problems, but I am not sure.

Answer 1

Properties that were not set will simply return the value of undefined. Only undeclared variables will actually raise a ReferenceError, this is where you then have to use typeof foo === 'undefined'.

So yes, your code will work.