Couple days ago, I started working on online IDE using https://ace.c9.io/ .. All the functions they have are good, but documentation wasn't that good and I had to learn things by my own. I customized a theme for it to look more like atom lol, added snippet menus and some other stuff, but thinking about it the reason I started is that i saw Thimble by Mozilla and felt jealous because it looks so cool, and I want to make some thing like it.