I recently used an xor in a JavaScript project at work and ended up adding 7 lines of comments to explain what was going on. The justification for using xor in that context was that one of the terms (term1 in the example below) could take on not two but three values: undefined, true or false while the other (term2) could be true or false. I would have had to add an additional check for the undefined cases but with xor, the following was sufficient since the xor forces the first term to be first evaluated as a Boolean, letting undefined get treated as false:
if (term1 ^ term2) { ...
It was, in the end, a bit of an overkill, but I wanted to keep it in there anyway, as sort of an easter egg.
