It's a pretty straightforward use-case: you have a function that returns a function, and in the case of an internal error, you want the returned function to hav

It's a pretty straightforward use-case: you have a function that returns a function, and in the case of an internal error, you want the returned function to have a reference to the error object. And the only reliable way to do that is to declare a variable with function scope, declare a function in function scope, and conditionally return this function? That's absurdly broken. As for variable scoping rules, if you have never been bitten by loop counters being used improperly, then I assert that you haven't programmed enough javascript. There are so many ways to mess this up: forget a var declaration and it leaks scope -- and since you can only declare it once, you can't just always use "for (var i = ...". If you want to defer access to a loop counter, then you have to remember to explicitly pass it by value to an inner closure. That last one in particular bites me all the time -- JSLint at least warns you about the first one.