Similar. Built a very complex app officially aimed at oldIE but made a point of ensuring it worked on other browsers too, largely on a skunkworks basis. A few years later (when we're no longer actively working on the app) everyone switched to Chrome and it Just Worked. Someone tried it on an iPad and it Just Worked (modulo some fat-finger challenges with small UI affordances).

At the time, jQuery was a big help in this, especially in hiding the event model mess. Things are a lot better now. Although I do wish we had a strict compatibility-checking layer that'd warn you if you used any feature of the web platform that wasn't supported by everything you wanted to support.