What is a Custom Hook?

First, a hook in React is a special function that lets you "hook into" React features, like state management and side effects, without writing a class. A custom hook is a hook you make yourself to reuse some behavior across different components.

Why Create Custom Hooks?

• Reuse Code: Avoid repeating the same logic in different components.
• Simplify Components: Keep the component code clean and focused on its primary job.
• Shareable Logic: You can share hooks between projects or with the community.

When to Use Custom Hooks?

• When you see duplicated logic across multiple components.
• For complex logic that involves state or lifecycle features, which you want to abstract away.
• When interacting with external data sources, like APIs, you want to centralize the fetching and error handling logic.

How to Create Custom Hooks - A Simple Guide

Step 1: Identify Common Logic

Look for patterns or repeated code in your components. This could be anything from fetching data, subscribing to a service, or even handling user inputs.

Step 2: Create a Hook

A custom hook is just a JavaScript function. The convention is to start its name with use, like useFetch for a data fetching hook.

Example: A Simple useFetch Custom Hook

Let's say we often fetch data from an API in multiple components. We can create a useFetch hook to make this process easier and reusable.

import { useState, useEffect } from 'react';


function useFetch(url) {
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);


  useEffect(() => {
    fetch(url)
      .then(response => response.json())
      .then(data => {
        setData(data);
        setLoading(false);
      })
      .catch(error => {
        setError(error);
        setLoading(false);
      });
  }, [url]); // Dependency array ensures this runs only when url changes


  return { data, loading, error };
}

Step 3: Use Your Custom Hook in Components

Now, instead of repeating fetch logic in every component, you can just use your useFetch hook.

function App() {
  const { data, loading, error } = useFetch("https://api.example.com/data");


  if (loading) return <div>Loading...</div>;
  if (error) return <div>Error: {error.message}</div>;


  return (
    <div>
      {/* Render your data here */}
    </div>
  );
}

Tips for Creating Custom Hooks

• Always start the hook name with use (like useData, useFormInput).
• Keep them focused. Each hook should have a clear, single purpose.
• Test them separately. Ensure your hooks work correctly in isolation before using them in components.