[valtism]

React is this for me. Before it, I was fumbling around with libraries like ExtJS for my first job, but after I started using it the concept of components that produce a view as a functional output of state really made so much sense to me.

It has given me so many powerful primitives to use while coding for the web

[JoeyJoJoJr]

I would also say Redux. Even though I grew to dislike Redux, understanding the power of reducers was quite mind blowing.

And further I would throw in Tanstack/Redux query.