I assume you had some error message: care to ask a bit more specifically?

Try looking up MDN's documentation for function.apply(). Specifically the first argument. It might help to know what a 'context' is.

I'm assuming javascript...

You're calling the method apply on an object, when it should be called on a function. This is probably because you're calling this.apply. Try presenting a = this and then calling a.apply - it's a weird JS bug.