if (file.type.match(textType) && file.size<1000)
...this will only upload small files. Torrent files are around 9kb.
1000 bytes is the max for size for sendMessage.
It wouldn't be too hard to chunk it and then create another message that contains an array of transaction ids.
Yep, that's what my application does. I don't think it would be too hard to convert into javascript.