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Brittney Postma
Brittney Postma

Posted on • Updated on • Originally published at console-logs.netlify.app

Create React App from Scratch

#react #webpack #babel #eslint

Table of Contents

TLDR: Just use create-react-app or this tool to help config webpack Create App.

Hi, I'm Brittney and I'm an instructor over at ZTM Academy and the owner, designer, and developer at bDesigned. You can find more dev notes by me at Console Logs.

Webpack

     Webpack is probably the most widely used module bundler. Webpack requires a lot of setup, but that also comes with a lot of control over what and how you want to use things. There are 4 main concepts in Webpack. Entry is a JavaScript file where Webpack will enter your project, typically index.js. Output is where you tell Webpack to output all of the files in bundles together, typically a build folder. Loaders are what you put your code through to compile or transpile your code, a popular tool for this is Babel. Lastly, Plugins play a vital role in outputting your code. Webpack has a rich plugin interface you can explore here: Webpack Plugins.

Build Webpack with React from Scratch

     Create React App comes with Webpack already pre-configured for you. This is going to teach you how it is done. Go to the directory of your choice and follow these steps to create a new project and setup Webpack.

  • 1. mkdir webpack-project and then cd webpack-project
  • 2. npm init - this will walk you through the steps of creating a basic package.json file.
  • 3. npm i --save-dev webpack webpack-dev-server webpack-cli - install webpack.
  • 4. mkdir build then cd build then touch index.html and touch bundle.js- create our build folder, html entry point, and js bundle file.
  • 5. cd .. to go back to the root directory of your project.

  • 6. touch webpack.config.js to create the webpack configuration file we will use next.

  • 7. Open up the project in your favorite editor. Mine is VS Code and I wrote a whole article on getting it setup with a good developer environment here VS Code Setup. In your package.json file we are going to edit the "scripts" section. Make sure your file looks like this unless you customized the package.json setup. Change the "scripts" section to include "start": "webpack-dev-server --config ./webpack.config.js --mode development" so we can run our server with Webpack using npm start.

{
  "name": "webpack-project",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "webpack-dev-server --config ./webpack.config.js --mode development"
  },
  "author": "",
  "license": "ISC",
    "devDependencies": {
    "webpack": "^4.43.0",
    "webpack-dev-server": "^3.11.0",
    "webpack-cli": "^3.3.11"
  }
}
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  • 8. mkdir src - in your root directory create a src folder.
  • 9. cd src then touch index.js to change into src folder and create our js entry point. Add console.log('Webpack wizard!') to the index.js file.
  • 10. Next, open up the webpack.config.js file and add the following code. 
module.exports = {
  entry: [
    './src/index.js' // The entry point
  ],
  output: {
    path: (__dirname = '/build'), // folder webpack should output files to
    publicPath: '/', // path to build directory
    filename: 'bundle.js' // file to output js to
  },
  devServer: {
    contentBase: './build' // dev server folder to use
  }
}
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  • 11. Now, open up the index.html file and add the following code. We will inject React into the div with id="app" and Webpack will bundle our js into the bundle.js file. 
<!-- index.html file -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Webpack Wizard</title>
  </head>
  <body>
    <h1>Webpack Wizard</h1>
    <div id="app"></div>
    <script src="/bundle.js"></script>
  </body>
</html>
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  • 12. At this step, we should check to ensure Webpack is configured correctly. Run npm start from the root directory. This will output some information to the terminal, but if you visit http://localhost:8080/ in your browser, you should see something like this.

webpack output

Part 2 - Build Webpack with React from Scratch

     Yay! Part 1 is done. Now, we move onto Babel to transpile our code back to ES5 so we have full browser support.

  • 1. npm i --save-dev babel-core babel-loader babel-preset-env babel-preset-react - in your root directory, install babel core, babel loader, and babel preset env.
  • 2. Open package.json and add "babel": { "presets": [ "env", "react" ]} to it. It should now look like this. 
{
    "name": "webpack-project",
    "version": "1.0.0",
    "description": "building webpack from scratch",
    "main": "index.js",
    "scripts": {
        "start": "webpack-dev-server --config ./webpack.config.js --mode development"
    },
    "babel": {
        "presets": [
            "env",
            "react"
        ]
    },
    "author": "Brittney Postma",
    "license": "ISC",
    "devDependencies": {
        "babel-core": "^6.26.3",
        "babel-loader": "^8.1.0",
        "babel-preset-env": "^1.7.0",
        "babel-preset-react": "^6.24.1",
        "webpack": "^4.43.0",
        "webpack-cli": "^3.3.11",
        "webpack-dev-server": "^3.11.0"
    }
}
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  • 3. In webpack.config.js add module: { rules: [{ test: /\.(js|jsx)$/, exclude: /node_modules/, use: ['babel-loader'] }]}, resolve: { extensions: ['js', 'jsx'] }. It now should look like this. 
module.exports = {
  entry: ['./src/index.js'],
  output: {
    path: (__dirname = '/build'),
    publicPath: '/',
    filename: 'bundle.js'
  },
  devServer: {
    contentBase: './build'
  },
  module: {
    rules: [
      {
        // test for all js and jsx files
        test: /\.(js|jsx)$/,
        // exclude node modules folder
        exclude: /node_modules/,
        // run all js and jsx through babel-loader
        use: ['babel-loader']
      }
    ]
  },
  resolve: {
    // makes it so you don't have to
    // write .js and .jsx at the end of imports
    extensions: ['js', 'jsx']
  }
}
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Part 3 - Build Webpack with React from Scratch

     Finally, Webpack and Babel are setup. The last step is to install React and ESLint.

  • 1. npm i react react-dom then npm i --save-dev eslint eslint-config-airbnb eslint-plugin-import eslint-plugin-jsx-a11y eslint-plugin-react eslint-plugin-react-hooks @babel/core @babel/preset-env @babel/preset-react babel-eslint babel-loader to install React and ESLint from your root directory.
  • 2. Now edit webpack.config.js to include { test: /\.(js|jsx)$/, exclude: /node_modules, use: ['eslint-loader'] } in the rules section. 
module.exports = {
  entry: ['./src/index.js'],
  output: {
    path: (__dirname = '/build'),
    publicPath: '/',
    filename: 'bundle.js'
  },
  devServer: {
    contentBase: './build'
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: ['babel-loader']
      },
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: ['eslint-loader']
      }
    ]
  },
  resolve: {
    extensions: ['.js', '.jsx']
  }
}
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  • 3. touch .eslintrc.json to create the ESLint configuration file.
  • 4. Open .eslintrc and input the following code to configure ESLint, and Babel. 
// .eslintrc
{
    "extends": ["airbnb-base"],
    "env": {
        "node": true,
        "es6": true,
        "browser": true
    },
    "parser": "babel-eslint",
    "rules": {
        "no-console": "off"
    }
}
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  • 5. Open package.json and add "babel": { "presets": ["@babel/preset-env","@babel/preset-react"] }, to configure babel.
  • 6. Finally, it is time to test our configuration. Run npm start 🍀 and fingers crossed it is working.

Warning - If you run into errors or issues when running npm start, which you probably will, then first try fully reading the error and then Googling the error. I spent an hour looking for the reason babel-core was missing and nothing worked. I looked down and saw this error and the answer was staring me in the face. I was using a deprecated version of babel and had to redo my entire setup.

Connect React

     The last thing to do is connect React and insert it into our div with the id="app" we created earlier. Remove the console log from src/index.js and we are going to build our React component.

import React from 'react'
import ReactDOM from 'react-dom'

const WebpackWizard = () => {
  return (
    <div>
      <h1>Webpack Wizard</h1>
    </div>
  )
}

ReactDOM.render(<WebpackWizard />, document.getElementById('app'))
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Congratulations! If you are still with me, we now have a working version of basically create-react-app, but we built it from scratch. 🎉

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