[codehero]

This is why you prepend the comma before every succeeding item in a list or map.

[swift]

This is what I do, but it basically just has the effect of making the first item special instead of the last. That's usually better in practice, though.

[Pxtl]

You've slightly improved the problem by moving it away from the last item on the list, but you've now screwed up the first item. You can no longer insert a first-item using the same format, and instead of a trailing comma bug you can get a starting comma bug.

[peferron]

This seems to only move the problem to the first item instead of the last one, not solve it.