React

React is not a large library. It has one central idea and about seven functions, and almost every difficulty people have with it comes from learning the functions without the idea. The idea is that you never update the interface. You update some state, describe what the interface should look like for any given state, and let React work out the difference. Everything else — hooks, re-renders, the dependency arrays that bite everyone — follows from taking that seriously.

The course starts with a crash course and a longer beginner course, then does something a little unusual: it spends a whole module on hooks individually, one short video each. This is deliberate. Hooks are usually taught in passing inside a project tutorial, which is exactly how people end up copying useEffect patterns for years without knowing what the dependency array does. Ten minutes each, learned properly, saves a great deal of confused debugging.

The order within that module matters too. useState and useEffect cover most real work; useRef and useMemo exist for specific problems you should be able to recognise; useContext and useReducer are for when state has outgrown the component holding it. Learning them in that order is learning them in the order you will need them.

About five hours required, and close to sixty in the pool — three more full courses, a module on state management, and a proper introduction to Next.js. React is unusually punishing to learn passively — the mental model only forms once you have watched your own component re-render at a moment you did not expect. Build something small and slightly too ambitious alongside it.