What is the best javascript framework for whatsapp-like web app?
I think there's a few key points your missing here: I don't connect a javascript framework into mysql, unless you're talking about a Node app, but based on the tags, I think you're referring to a front end application. You still need a back end application, and in creating a whatsapp like application (sxprojects), that's considerably more important than what kid of front end application you use. For that I'd suggest functional or high concurrency languages, like Go, like Erlang, Akka, Node that can rip through tons of requests, which is what happens with messaging services.