Build a Quiz App with React and Firebase

Intro and What We’ll Cover

We are going to build a Quiz app using React that enables saving of high scores in Firebase.This app will load random trivia questions from the Open Trivia DB API and allow users to run through x number of questions (typically 10) at a time.

Create Initial Project using Create React App

For this project, we are going to use Create React App to generate a starter React application. We will also use the built in NPM commands to run and build our application. We will also be copying in pre-written CSS instead of writing styles along the way.

create new Create React App application using NPX
copy in pre-written CSS
run locally

Create Home Page Component

We will create the initial home page/component. It will display a title and have two buttons, one to play/take a quiz and the other to view high scores.

create components directory
create Home component
add two buttons (one to play and one for High Scores)

Add React Router

For this application, our different pages (home, game, and high scores) are going to live on different routes. Since we need to show different components on different routes, we are going to use React Router. We will need to update our Home component to link to the Game and High Scores pages.

add react-router-dom NPM package
create stubbed out Game and High Scores components
wrap our application content with BrowserRouter
demo navigation

Create Question Component With Static Data

We will create the Question component which will be used to display quiz questions. We will create dummy question data to display. In the next video, we will load questions from the Open Trivia DB API.

create Question component
create dummy question data in Game component and pass it to the Question component

Load Questions using Fetch API

We will use the built in JavaScript Fetch API to retrieve questions from the Open Trivia DB API. We will need to convert the returned question data into the format we plan to work with. We will then load one of the questions to be displayed.

explore the Open Trivia DB API
use the Fetch API to make requests to API
convert question data to desired format

Move Code to Questions Utility Class

We will take some of the logic for requesting and parsing question data out of the Game Component into its own helper file. This will help to minimize the size of the component itself. We will also change the display of the question to handle encoding issues by using dangerouslySetInnerHTML().

create utility class to retrieve and convert question data
use dangerouslySetInnerHTML to fix encoding issues when displaying question data

Add an Animated Loader

It will take a small amount of time to retrieve questions from the API. Because of this, we will create and display an animated loader until the questions have been fully retrieved. We can use a throttle in the Chrome Developer tools to slow down the request to make sure the loader is visible.

create a loading state property (default to true)
update loading property to false after retrieving questions
display loader while loading is true

Add Logic to Change Questions

After retrieving a set of random questions from the API, we will add the logic to choose a random question to start with and change questions as the user answers each one.

create changeQuestion() function
choose random question
remove it from list of questions going forward
set random question as current question in state

Add Answer Validation Logic

As the user answers each question, we will add logic to validate the answer. Based on the user’s answer, we will display a green or red background for correct and incorrect answers accordingly. In this section, we will introduce React Hooks. This will allow use to write these components as functional components instead of class based ones but still track state.

create checkAnswer() function
compare user's selected answer to correct answer
highlight selected answer green/red based on correctness

Add Score Tracking Logic

As the user answers questions, we additionally need to keep track of the user’s score. This score will then be used when the user completes the quiz and optionally saves it to Firebase.

create score variable on state
update appropriately score after answering question

Create Heads Up Display Components

We will create a few components to display information to the user about the state of the quiz. We will display the current question number as well as the score. We will create and display a progress bar component to show the user how far he/she has progressed through the quiz.

create HUD component
create progress bar component
display question number, score, and progress bar

Add Quiz Completed Logic

We will add the logic to track when the user has finished the quiz and set a “done” flag to be true. This flag will be used to conditionally show the save high score component in the next couple of videos.

create done variable on state
update done state to true when there are no questions left

Create Save High Score Component

We will create the High Score component that the user will use to save his/her high score. This will be a simple form that displays the user’s name and then prompts for a username.

create SaveHighScore component
add form with username input and save button

Score Bug Fix and Code Cleanup

In the previous section, we created a bug in score tracking. If the user answered the question correctly, the score was not being updated. We will fix this bug and do a little bit of cleanup in the JSX of our Game component.

Create Project in Firebase

We will create the Firebase project that we will interact with add and display high scores. We will store the necessary credentials for connecting to Firebase inside of a .env file.

Don't ever check in your .env files to source control. I've included a sample file for you to reference.

create new Firebase project
add Firebase credentials to .env file

Connect React Project to Firebase

We will set up our React application to be able to talk to Firebase. We will use the React Context API combined with React Hooks to share the firebase instance between components.

install firebase package from NPM
create Firebase class
create Firebase Context and useFirebase Hook
wrap the application in Firebase Context

Save High Scores to Firebase

We will add the logic to have the High Score component actually save high scores in the Firebase database. After the score has been saved, the user will be taken to the home screen.

use Firebase object to save high score
navigate home after score is saved

Display High Scores

With users being able to save their high scores, we now need to be able to display them. We will now make a request to the Firebase DB to retrieve and display real high scores.

use Firebase object to read high scores
convert high score data to correct format
display high scores

Convert Game Component to React Hooks

Since the game component is significantly more intensive than the other components, we did not write it using React Hooks initially. Now that you have a bit of experience with React Hooks from the other components, we will refactor this one to use React Hooks as well.

convert Game Component to functional component
use useEffect() and useCallback()

Deploy to Netlify

We will create a new website in Netlify by connecting it to our github repository. We will then configure Netlify to build out site every time we push a change to the code. By hosting in Netlify, you can share your app with anyone across the world.

create Netlify account (if necessary)
create Github repository
create website in Netlify connected to Github repo

Wrap Up and Where to Go From Here

We will recap what we covered in this series and talk about potential next steps and features you can add to your trivia game to go above and beyond.

alex-wengg / build-a-quiz-app-with-react-and-firebase Goto Github PK