FAQ: The Effect Hook - Separate Hooks for Separate Effects

This community-built FAQ covers the “Separate Hooks for Separate Effects” exercise from the lesson “The Effect Hook”.

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This exercise can be found in the following Codecademy content:

Learn React

FAQs on the exercise Separate Hooks for Separate Effects

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I have reported a bug. My code below was “passed” as valid from the existing “tests” installed in the dependency files. My code below is WRONG. The app did not work even though my code passed all the tests. So, I did find the errors by comparing my code to the solution and suggest if your app is not working you might compare your answer side by side to the solution to discover the simple fix. You can see in my code below the incorrect syntax was used for the setters.


should have been

//mine is different than the given solution but the Codecademy solution checker doesn't catch the mistakes. 
//you must compare to the solution to see your mistakes from this point.  
import React, { useState, useEffect } from 'react';
import { get } from './mockBackend/fetch';

export default function SocialNetwork() {
  const [menu, setMenu] = useState(null);
    useEffect(() => {
      get('/menu').then((response) => {
   }, []);

  const [newsFeed, setNewsFeed] = useState(null);
  useEffect(() => {
    get('/news-feed').then((reponse) => {
  }, []);

  const [friends, setFriends] = useState(null);
  useEffect(() => {
    get('/friends').then((response) => {
   }, []);

  return (
    <div className='App'>
      <h1>My Network</h1>
      {!menu ? <p>Loading..</p> : (
          {menu.map((menuItem) => (
            <button key={menuItem}>{menuItem}</button>
      <div className='content'>
        {!newsFeed ? <p>Loading..</p> : (
            {newsFeed.map(({ id, title, message, imgSrc }) => (
              <article key={id}>
                <img src={imgSrc} alt='' />
        {!friends ? <p>Loading..</p> : (
                .sort((a, b) => (a.isOnline && !b.isOnline ? -1 : 0))
                .map(({ id, name, isOnline }) => (
                  <li key={id} className={isOnline ? 'online' : 'offline'}>

useEffect(() => {
  const handleMove = (event) => ...

Why is an event handler being defined in useEffect()?

Perhaps it has to do with the fact that this particular useEffect is being called with an empty dependency array. This means that the effect doesn’t get called after every render. The effect is only called once i.e. after the first render. Similarly, the cleanup function is also called once i.e. after the last render. Since the handleMove event handler is not being used elsewhere and the useEffect is only going to get triggered just once, so the definition of the event handler is not going to happen multiple times. Packaging the definition with the effects works adequately for this particular case. If the dependency array was omitted or a non-empty dependency array was used, then defining the event handler within the useEffect would not be suitable because the useEffect would be triggered multiple times.