I suspect some of the JS frameworks started with a set of JS functions, etc. to do things dynamically on a page. And it grew. And then someone comes by and says

I suspect some of the JS frameworks started with a set of JS functions, etc. to do things dynamically on a page. And it grew. And then someone comes by and says "hey we're building a new app, mind if we use that?". And it was cloned and morphed. And it grew. Maybe that repeated a bit, and then someone created a framework of generic tools. Then this happened in multiple places. Or hackers didn't like how something worked so they came up with their own spin. I believe React came out of or is strongly influenced by FB, which makes sense - a Single Page App is the design and progressively loading more ads, ahh I mean content. And here we are building client/server apps with a technology invented for document sharing. There are 2 frameworks solving the "keep track of state" problem on the server and allowing for dynamic/reactive UI via web sockets instead of XHR: Ruby/Rails 7 and Elixir/Phoenix LiveView. They still use JS but you can limit it to client-side things and maintain state and validations on server.