⚡ React Performance 🚀 EpicReact.Dev

React is fast, until it isn't

Learn everything you need to diagnose, profile, and fix performance problems in your React application using the Browser Performance Profiler, React DevTools Profiler, and proven React optimization techniques.

Prerequisites

Install the React DevTools (Chrome (recommended), Firefox)
Experience with React and all hooks

NOTE: The EpicReact.dev videos were recorded with React version ^16.13 and all material in this repo has been updated to React version ^18. Differences are minor and any relevant differences are noted in the instructions.

Quick start

It's recommended you run everything in the same environment you work in every day, but if you don't want to set up the repository locally, you can get started in one click with Gitpod, CodeSandbox, or by following the video demo instructions for GitHub Codespaces.

For a local development environment, follow the instructions below

System Requirements

git v2.13 or greater
NodeJS 14 || 16 || 18
npm v6 or greater

All of these must be available in your PATH. To verify things are set up properly, you can run this:

git --version
node --version
npm --version

If you have trouble with any of these, learn more about the PATH environment variable and how to fix it here for windows or mac/linux.

Setup

If you want to commit and push your work as you go, you'll want to fork first and then clone your fork rather than this repo directly.

After you've made sure to have the correct things (and versions) installed, you should be able to just run a few commands to get set up:

git clone https://github.com/kentcdodds/react-performance.git
cd react-performance
node setup

This may take a few minutes. It will ask you for your email. This is optional and just automatically adds your email to the links in the project to make filling out some forms easier.

If you get any errors, please read through them and see if you can find out what the problem is. If you can't work it out on your own then please file an issue and provide all the output from the commands you ran (even if it's a lot).

If you can't get the setup script to work, then just make sure you have the right versions of the requirements listed above, and run the following commands:

npm install
npm run validate

If you are still unable to fix issues and you know how to use Docker 🐳 you can setup the project with the following command:

docker-compose up

Running the app

To get the app up and running (and really see if it worked), run:

npm start

This should start up your browser. If you're familiar, this is a standard react-scripts application.

You can also open the deployment of the app on Netlify.

Running the tests

npm test

This will start Jest in watch mode. Read the output and play around with it. The tests are there to help you reach the final version, however sometimes you can accomplish the task and the tests still fail if you implement things differently than I do in my solution, so don't look to them as a complete authority.

Exercises

src/exercise/00.md: Background, Exercise Instructions, Extra Credit
src/exercise/00.js: Exercise with Emoji helpers
src/__tests__/00.js: Tests
src/final/00.js: Final version
src/final/00.extra-0.js: Final version of extra credit

The purpose of the exercise is not for you to work through all the material. It's intended to get your brain thinking about the right questions to ask me as I walk through the material.

Helpful Emoji 🐨 💰 💯 📝 🦉 📜 💣 💪 🏁 👨‍💼 🚨

Each exercise has comments in it to help you get through the exercise. These fun emoji characters are here to help you.

Kody the Koala 🐨 will tell you when there's something specific you should do
Marty the Money Bag 💰 will give you specific tips (and sometimes code) along the way
Hannah the Hundred 💯 will give you extra challenges you can do if you finish the exercises early.
Nancy the Notepad 📝 will encourage you to take notes on what you're learning
Olivia the Owl 🦉 will give you useful tidbits/best practice notes and a link for elaboration and feedback.
Dominic the Document 📜 will give you links to useful documentation
Berry the Bomb 💣 will be hanging around anywhere you need to blow stuff up (delete code)
Matthew the Muscle 💪 will indicate that you're working with an exercise
Chuck the Checkered Flag 🏁 will indicate that you're working with a final
Peter the Product Manager 👨‍💼 helps us know what our users want
Alfred the Alert 🚨 will occasionally show up in the test failures with potential explanations for why the tests are failing.

Contributors

Thanks goes to these wonderful people (emoji key):

_{Kent C. Dodds} 💻 📖 🚇 ⚠️	_{Justin Dorfman} 🔍	_{Frédéric Bolvin} 📖	_{Vojta Holik} 💻 🎨	_{Marco Moretti} 💻	_{Ricardo Busquet} 💻	_{Selwyn Yeow} 💻
_{Emmanouil Zoumpoulakis} 📖	_{Peter Hozák} 💻	_{Pritam Sangani} 💻	_{Christian Schurr} 💻 📖	_{Johnny Magrippis} 💻	_Ahmed 💻 📖	_{Robbert Wolfs} 📖
_{Kim Gwan-duk} 📖	_{Rasmus Josefsson} 💻	_{Marcos NASA G} 📖	_{Markus Lasermann} 📖	_{Vasilii Kovalev} 📖	_{Matan Kushner} 📖	_{Michaël De Boey} 💻
_{Veljko Blagojevic} 📖	_{Bobby Warner} 💻	_{Jesús Rodríguez} 📖	_{Valentin Hervieu} 🐛	_{David Sánchez} 📖	_{Merott Movahedi} 📖	_{Arjen Bloemsma} 📖
_{Naveed Elahi} 📖	_{Tyler Knappe} 📖	_0xnoob 💻 📖	_{Emil Esplund} ⚠️	_{Justin Stanley} ⚠️	_{Pavlos Vinieratos} 📖	_{Joe Barrett} 💻
_LochMess 📖	_Michal 📖	_{Mario Sannum} 💻	_CJThornburg 📖	_{Luciano Ayres} 📖	_{Sushil Kumar} 💻