Build Your Own (Simple) React From Scratch!

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Have you ever wondered how React works?

What would it feel like to create the magical lines that make up the tool we all grew to learn and love?

Come along on our journey to implement React from scratch, making a simple React project work with your own my-react.js library.

What's included

- Introduction

- Rendering our first component

- Update cycle and the VDOM

- Meet the hooks


- Some knowledge of React.

Sean Blundell
Sean Blundell
Jean Duthon
Jean Duthon
112 min
28 Nov, 2022


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Video Summary and Transcription

This Workshop focuses on creating a React app from scratch and covers topics such as rendering components, handling state, and optimizing rendering. It provides step-by-step instructions and a GitHub repository with a test case and boilerplate code. The workshop also explores the use of hooks, such as useState and useEffect, for state management and handling side effects. The implementation includes a diff module to optimize rendering by identifying specific elements that require updates. Overall, the Workshop offers a comprehensive understanding of React development and provides practical examples for building a React app.

1. Introduction to React Workshop

Short description:

This workshop today will be creating our own React from scratch. We'll cover React basics, rendering components, handling state, diffing, and targeting updates. We have a GitHub repository with a to-do app as a test case and a boilerplate for your own version of React. The process is step by step with branches for each step and solutions available. Questions can be asked in the Discord channel. Clone the repository, navigate to the terminal, open the repo in your text editor, and follow the instructions in the read-me. React is a declarative, component-based JavaScript library that uses props to pass data through the application.

Gotcha! Yeah, so for those that are just joined, this workshop today will be creating our own React from scratch. So, how are we gonna do this? So, the agenda for today, it's the three-hour workshop, so I appreciate your time and also your patience. I'm gonna kick off with a small introduction and then look at some React basics quickly and then we're going to move on to, this workshop's kind of split into four chapters, where the first chapter's going to look at how do we render components in our intro to the virtual DOM, which is a key part of React, how we handle state. Is the second chapter, then chapter three will be about diffing and how do we target updates for a specific component rather than rendering the whole application and then our last chapter, we'll look at the user effect specifically.

We've just got some more latecomers. So this is kind of an important part about this workshop. We've created a GitHub repository for you. And this repository contains two things, a simple to do React application to add items to your to do list, you won't be touching that, but the repo also contains a boilerplate for your own version of React which is what we will be editing. And the goal at the end of the workshop is to have all the features of the to do app working with your own version of React. And the process is step by step. So, we've created branches for each step, which contains also then the solutions to the previous step. So, it's kind of an iterative approach and hopefully will be quite easy to follow. And if not, you've got the solutions available at the next step. And if you have questions, we'd ask you not to ask them here. But in the Discord channel, which you should have all access to. Maybe I can drop it in the link in case you haven't. I'll add it to the chat. I can find the chat. I'll drop it in the chat after. Or maybe, Zsányi, you can put in the chat.

So first things first, we need to clone our repository. That is also available in the Discord chat, I provided a link. So first thing is to clone that repository. So navigate to your terminal, clone it, then navigate into the directory and open the repo in your text editor of choice. And then all further instructions are in the read-me. That's your best friend and guide. And we also have quite extensive docs in the repository, too, that can help cover key concepts and give a bit more information in a detailed way about the concepts that we'll be covering in each step. And the slides from this point on are just kind of focusing on some overarching React concepts. All the fun will be happened in your own kind of code editor.

So, what is React? React is a JavaScript library. And key thing about it is it's declarative. Which means that your code is in a way that describes what you want to do and not how you want to do it. The great thing about React, it's component-based. So, you create lots of encapsulated components that are responsible for their own state. And they take in input data, which we call props. And it's written in JavaScript instead of a template language. So, data can easily be passed through your application by these props. And it helps keep state out of the dump. And I'm now going to pass over... Oh, no. So, let's meet the project first. So, as I said, we've got a to-do app, we won't be touching that. But we'll use it as kind of our test case. So, you can kind of test your progress. And, yeah, it uses all the concepts that we are trying to learn throughout this workshop. And again, our version of React. Let me just get more people in. So, if you've cloned the repository, just for those who have joined, you can access the GitHub repository in the Discord channel. And you need to clone that and then open it up. But I'm going to then navigate to what that repository looks like, quickly.

2. Setting Up the Environment and Updating Key Files

Short description:

To get started, change into the repository and run npm install to install the required dependencies. Once installed, start the local development server with npm start. Inside the packages folder, you'll find our own React version, which includes the key files we'll be updating. The index file acts as the entry point where we'll handle React's functions like state, effects, and rendering.

So, it should look like this. You want to first probably say change into the repository. And you want to do an npm install. So, that we install all of our dependencies that we require. And once those are installed, we want to run npm start. Which starts our local development server. And let's take a quick look at our kind of file structure. So, we have the todo app, which contains our React app. Don't really need to look into that. But what we do need to look into is inside this packages folder, which contains our own React version. And these are the key files that we will then be updating. And this index file kind of acts as our entry point. And it's where we'll be replacing React's functions that we want to handle. Such as the state, these effects, our render functions and things like that.