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Create the App | React Todos

Table of Contents

Step 1 - Creating a new directory

create-react-app will create a new directory for our frontend application as well as handle the heavy lifting of configuring all of our build tools.

  1. Create a new folder to contain the frontend, and eventually the backend, application. Open a terminal window, navigate to the new folder, and run the command:
npx create-react-app web --skip-git
  1. Next create a package.json file and copy into it the following:
"scripts": {
"start": "npm --prefix web start",
"postinstall": "npm i --prefix web"
  1. Then create a .gitignore file and copy into it the following:
  1. Finally return to the terminal and run the command:
npm run start

You'll be greeted by the following screen:

create react app result

Step 2 - Starting with a blank canvas

While the introductory application is nice, we'll want to start with a blank canvas.

  1. Open up the amplication-react directory in the IDE of your choice.

  2. Open up web/src/App.css and delete all the content in this file. Delete the file web/src/logo.svg.

  3. Open web/src/index.css and replace the content of this file with the following:


:root {
--spacing: 4px;
--font-size: 20px;
--on-primary: #ffffff;
--on-secondary: #ffffff;
--primary: #f44336;
--secondary: #2196f3;
--text: #212121;

body {
margin: 0;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto",
"Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans",
"Helvetica Neue", sans-serif;
-webkit-font-smoothing: antialiased;
-moz-osx-font-smoothing: grayscale;

button {
border: none;
background-color: var(--secondary);
color: var(--on-secondary);
font-size: var(--font-size);
height: 60px;
margin: var(--spacing) 0;
max-width: 450px;
width: 100%;

button[type="submit"] {
background-color: var(--primary);
color: var(--on-primary);
text-transform: uppercase;

button:hover {
filter: brightness(80%);

button:active {
filter: brightness(120%);

code {
font-family: source-code-pro, Menlo, Monaco, Consolas, "Courier New",

form {
align-items: center;
display: flex;
flex-direction: column;
margin: var(--spacing) 0;
padding: calc(4 * var(--spacing));

input {
background: transparent;
border: 1px solid var(--text);
border-radius: 3px;
line-height: 30px;
font-size: var(--font-size);
margin: var(--spacing) 0;
max-width: 416px;
padding: calc(4 * var(--spacing));
width: 100%;

input[type="checkbox"] {
height: 48px;
margin: var(--spacing);
width: 48px;

li {
display: flex;
height: calc(48px + calc(2 * var(--spacing)));
max-width: 450px;
width: 100%;

li.completed {
text-decoration: line-through;

span {
flex: 1;
font-size: var(--font-size);
line-height: calc(48px + calc(2 * var(--spacing)));

ul {
align-items: center;
display: flex;
flex-direction: column;
list-style-type: none;
padding: calc(4 * var(--spacing));
  1. Then open web/src/App.js and replace the content in this file with below:


import "./App.css";

function App() {
return <div></div>;

export default App;

Step 3 - Adding our components

To build this todo list app, we'll need a few components.


Our first component will be used to render an individual task. It takes in as parameters:

  • task - The task object itself. It has the following properties:
    • text - A string of the task itself.
    • completed - A boolean property that tracks if a task is completed.
    • id - A unique number to identify a task.
  • toggleCompleted - This function bubbles up when a user taps on the checkbox, toggling the state of the task.

Create the following file with this code.


import { useState } from "react";

export default function Task({ task, toggleCompleted }) {
const [completed, setCompleted] = useState(task.completed);

return (
<li className={completed ? "completed" : "incompleted"}>
onClick={() => toggleCompleted(}
onChange={() => setCompleted(task.completed)}


Our second component will be used to render a list of tasks. It takes in as parameters:

  • tasks - An array of tasks.
  • toggleCompleted - This function bubbles up when a user taps on the checkbox in the Task component, toggling the state of the task.

Create the following file with this code.


import Task from "./Task";

export default function Tasks({ tasks, toggleCompleted }) {
return (
{ => (
<Task key={} task={task} toggleCompleted={toggleCompleted} />


The final component will be a form to allow users to create a new task. It takes in as parameters:

  • addTask - This function bubbles up when a user submits the form with the new task they want to create.

Create the following file with this code.


import { useState } from "react";

export default function CreateTask({ addTask }) {
const [task, setTask] = useState("");

const handleChange = (e) => {

const handleSubmit = (e) => {

return (
<form onSubmit={handleSubmit}>
<button type="submit">Add</button>

Step 4 - Putting it together

With our different components created, we'll next put them together and see how they work!

  1. Open up web/src/App.js and import React's useState function as well as our newly created CreateTask and Tasks components.
+ import { useState } from "react";
import "./App.css";

+ import CreateTask from "./CreateTask";
+ import Tasks from "./Tasks";
  1. In the App function we will want to create our tasks array, so we'll use useState to create a reactive array.
function App() {
+ const [tasks, setTasks] = useState([]);
  1. We'll also want ways to add and toggle the state of tasks.
function App() {
const [tasks, setTasks] = useState([]);

+ const createTask = (text, id) => ({
+ id,
+ text,
+ completed: false,
+ });
+ const addTask = (task) => {
+ const temp = [...tasks];
+ temp.push(createTask(task, tasks.length));
+ setTasks(temp);
+ };
+ const toggleCompleted = (id) => {
+ let temp = [...tasks];
+ const i = temp.findIndex((t) => === id);
+ temp[i].completed = !temp[i].completed;
+ setTasks(temp);
+ };
  1. With all of our logic and components in place, we'll finally render our components! Replace the return statement with the following so we can see our tasks list and add tasks to that list.
return (
<CreateTask addTask={addTask} />
<Tasks tasks={tasks} toggleCompleted={toggleCompleted} />
  1. Go to GitHub and create a new repository.

  2. Run the following commands in the working folder.

git init
git add .
git commit -m "first commit"
git branch -M main
  1. Finally, set your remote origin URL and push up the code.
git remote add origin <URL copied from github repository>
git push origin main

Step 5 - Wrap Up

Go ahead and try adding tasks or marking them as complete.

The only problem is that these tasks aren't being saved anywhere, so when you refresh the page poof they're gone. In our next step, we will create our backend with Amplication to be able to save our tasks to a database!

To view the changes for this step, visit here.