Back in the days I've used to write libraries, generic algorithms and functions targeting ActionScript 3 (Flash) in HaXe to be able to quickly unit test them, but use them in the actual Flash projects. To unit test AS3/Flash code directly was a pain. HaXe speed up the dev workflow tremendously. Having very good memories. Now I just use modern JavaScript and TypeScript directly. But HaXe has a warm place in my heart and I am glad it still exists.