Only merge files ending in .js from ./chat-plugins/

i.e. stop trying to merge ViM swap files during testing
Does ``.indexOf()`` make sense to use if you're looking for it to return 0? From the analogy you made, it makes it sounds like ``.substr()`` has to grab the length of text it's told to use, then compare, but ``indexOf()`` would search for the string it's told to look for and quickly finds it at index 0.