Can I make games using ONLY javascript?

I don't know of any tutorials doing so, but you have to keep in mind that Javascript is meant to be for a specific use case. It is not a language like C#, Java or any other VM-compiled language.

Javascript is a single threaded, non-blocking IO language, meaning that its use case is fetching some data or doing some operation and coming back to that in the future. If you are planning on doing heavy processor work in your game, Javascript is not the right language. An example of heavy processor work is calculating a Mandelbrot collection. It works perfectly fine if it's for one person, but if you want to do other tasks, the Javascript thread (think of updating the UI or doing HTTP requests) will choke. It is however an excellent language for running a game loop (waiting some time and executing a function when it's time), doing some quick updates, etc.

TLDR; You can build games in Javascript, but it is definitely not the go-to language when building games. A better language might be C(++), a VM-compiled language (C# or Java) or a language which does support multi-threading.

/r/javascript Thread