W3Schools.com

l is great for explaining web frontend programming.

React Home | React Intro | React Get Started | React UpgradeReact ES6 | React Render HTML | React JSX | React Components | React Class | React Props | React Events | React Conditionals | React Lists | React Forms | React RouterReact Memo | React CSS Styling | React Sass Styling

React Hooks

What is a Hook? | useState | useEffect | useContext | useRef | useReducer | useCallback | useMemo | Custom Hooks

React Exercises

React Compiler | React Quiz | React Exercises | React Bootcamp | React Certificate