I want to disable the two finger swipe that causes Chrome going back or forward. I have a website where the user might lose progress on his work if he doesn't specifically saves.
I have tried using window.onbeforeunload but that doesn't seem to work if I have hashes in the url (back forward would change between www.example.com/work/#step1#unsaved www.example.com/work/#step0) and the event doesn't seem to trigger.
I was about to switch to another solution but today I noticed that in Google Docs it's completely disabled. How did they achieve that?
You're looking at the problem at the wrong level. OnBeforeUnload is simply not triggered because there is nothing being unloaded from the browsers perspective. Therefore you have, quite bluntly, implemented the wrong mechanism for versioning - fragments are for page states, not document states as you are using it now.
If you insist on maintaining state through hash fragments you need to use another mechanism to guard against page state changing. Since all current browsers support LocalStorage I'd use that. And well, while at it, put all the document state data there instead of in the URL, since that is how Google Docs does it and that is why they don't have this issue.