React Custom Hooks Examples - Practical Tutorial

import { useState, useEffect } from 'react';

function useWindowWidth() {
  const [width, setWidth] = useState(window.innerWidth);

  useEffect(() => {
    function handleResize() {
      setWidth(window.innerWidth);
    }
    window.addEventListener('resize', handleResize);
    return () => window.removeEventListener('resize', handleResize);
  }, []);

  return width;
}

import { useState } from 'react';

function useFormInput(initialValue) {
  const [value, setValue] = useState(initialValue);

  function handleChange(e) {
    setValue(e.target.value);
  }

  return {
    value,
    onChange: handleChange
  };
}

import { useState, useEffect } from 'react';

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

  useEffect(() => {
    setLoading(true);
    fetch(url)
      .then(response => {
        if (!response.ok) {
          throw new Error('Network response was not ok');
        }
        return response.json();
      })
      .then(json => {
        setData(json);
        setLoading(false);
      })
      .catch(err => {
        setError(err);
        setLoading(false);
      });
  }, [url]);

  return { data, loading, error };
}