Question

How do I test if a variable in my javascript code is initialized?

This test should return false for

var foo;

and true for

var foo = 5;

Answer 1

if (foo === undefined) { /* not initialized */ }

or for the paranoid

if (foo === (void) 0)

This is the sort of thing that you can test right in your JavaScript console. Just declare a variable and then use it in (well, as) an expression. What the console prints is a good hint to what you need to do.