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Summary - Advanced custom hooks

Combine useFetch with useDebounce to write a search box.

Summary - Advanced custom hooks

In this group we wrote three powerful custom hooks: useLocalStorage for persistent state, useFetch for data fetching, and useDebounce for slowing changes. All three are daily tools in real projects.

The common principle: hooks combine state and effect, pull complex logic out of components, and form testable, reusable pieces. Composable structures can be built by nesting hooks.

In the next step you'll write a data page with useFetch; you'll handle loading and error states.

Practice DataPage with useFetch

Complete the skeleton. Write a DataPage component. Call useFetch("https://api.example.com/items"); destructure as [data, loading, error]. If loading, show <p>Loading</p>; if error, show <p>Error</p>; otherwise <p>{ '{ data.length }' } items</p>. Export it.

Starter code

App.jsx
// Write the DataPage component here

Sample solution

App.jsx
function DataPage() {
  const [data, loading, error] = useFetch("https://api.example.com/items");
  if (loading) return <p>Loading</p>;
  if (error) return <p>Error</p>;
  return <p>{data.length} items</p>;
}

export default DataPage;

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Which hook is ideal for a search box?

  • useDebounce Correct answer
  • usePrevious
  • useToggle
  • useCounter

Explanation: useDebounce is ideal for search boxes.

2 Match the three hooks

Term Meaning
useLocalStorage Persistent
useFetch Data
useDebounce Delay
useEffect Side effect

All lessons in Intermediate

1 Custom hook basics

  1. What is a custom hook?
  2. useToggle
  3. usePrevious
  4. Summary - Custom hook basics

2 Advanced custom hooks

  1. useLocalStorage
  2. useFetch
  3. useDebounce
  4. Summary - Advanced custom hooks

3 Context deep dive

  1. Context separation
  2. Context + useReducer
  3. Default value and error
  4. Summary - Context deep dive

4 useReducer pattern

  1. The reducer pattern
  2. Action types
  3. Composition
  4. Summary - useReducer pattern

5 Cart management

  1. Project: Cart management
  2. Cart reducer
  3. Cart context
  4. Add product UI

6 useMemo

  1. What is useMemo?
  2. Dependency control
  3. Pitfalls
  4. Summary - useMemo

7 useCallback

  1. What is useCallback?
  2. Sibling re-render
  3. useMemo vs useCallback
  4. Summary - useCallback

8 React.memo

  1. What is React.memo?
  2. Prop comparison
  3. Custom comparator
  4. Summary - React.memo

9 Performance project

  1. Project: Performance
  2. Expensive computation
  3. Stable handler
  4. Memoized list

10 Router basics

  1. What is React Router?
  2. Defining routes
  3. Link and NavLink
  4. Summary - Router basics

11 Advanced router

  1. URL parameters
  2. Nested routes
  3. Programmatic navigation
  4. Summary - Advanced router

12 Multi-page app

  1. Project: Multi-page app
  2. Layout and router
  3. List and detail
  4. Navigation and 404

13 Layout components

  1. The layout pattern
  2. Sidebar and header
  3. Layout with Outlet
  4. Summary - Layout components

14 Error boundary

  1. What is an error boundary?
  2. Class component structure
  3. Fallback UI
  4. Summary - Error boundary

15 Suspense and lazy

  1. What is React.lazy?
  2. Suspense boundary
  3. Multiple boundaries
  4. Summary - Suspense and lazy

16 Portals

  1. What is a portal?
  2. Modal example
  3. Event bubbling
  4. Summary - Portal

17 Advanced useRef

  1. useRef and computation
  2. Measuring
  3. forwardRef
  4. Summary - Advanced useRef

18 RTL tests

  1. React Testing Library
  2. render and screen
  3. Firing events
  4. Summary - RTL tests

19 Dashboard project

  1. Project: Dashboard
  2. Layout and route
  3. Stats widget
  4. Add via modal

20 Intermediate final

  1. Challenge: useFetch hook
  2. Challenge: Theme provider
  3. Challenge: Memoized list
  4. Challenge: Routed cart