I've used it before, but I forgot the name. Its purpose is to provide very effective code completion. This tool works by executing the file you are currently editing and reads fields of all the variables in real-time, so it provided very accurate code completion suggestions. It was similar to TernJS in a way, because you have to start a server first, then a plugin for your text editor connects to the server and gets code completion data from there. I believe it was written by Russian developers. Does anyone remember something like this?
It turns out the tool I was looking for is called COLT. Its main purpose is live reloading of js/html/css, but it can also do decent code completion. I don't think it's being supported anymore.