[fyp]

I don't know the details but I heard the original codebase was javascript but they used an automated script to convert it to coffeescript as an hack week project! That's some serious long term damage they did in that one week.

Edit: Found the 2012 post, pretty useful for doing a postmortem https://dropbox.tech/application/dropbox-dives-into-coffeesc...

[dgoldstein0]

I don't view it so black and white. While certainly parts of how we ended up using coffeescript weren't great and ended up causing lots of problems, in 2012 it looked like a net win - we got a bunch of new language features several years before they were actually standardized in any form.

It wasn't until 2015 that es6 came around, and we saw how things could be better; and typescript didn't have much momentum until 2015 either. Without a crystal ball, it'd have been very hard to predict this shift.

[city41]

I wonder if Dropbox devs would say CoffeeSctipt was a net negative. The authors mentioned how it made supporting IE11 easier for example.

[arkanciscan]

The devs that did it probably quit immediately after and started a consulting company where they advised all their clients on how to convert to coffeescript too