Building a React ecosystem from scratch

What do we need?

• An entry point
• Support ES6 and JSX
• Building and serving with Webpack
• React-hot-loader

---

An entry point

1. Create a folder to hold the project
2. Go to this folder and run npm init -y to initialize a new npm package
3. Create a public folder to hold our static code
4. Create a src folder to hold our React code
5. Create an index.html file inside the public folder. This is what is sent to the client when a request to our website is made by the user.
6. Create a div with id="root" in the index.html. This div will receive the React content.
7. Add a script tag to load the React code: <script src="../dist/bundle.js"></script> (it doesn't exist yet)

Support ES6 ans JSX

1. Install Babel compiler npm i --save-dev @babel/core @babel/cli @babel/preset-env @babel/preset-react
2. Create a .babelrc file in the root of the project to tell Babel which presets and plugins should be used to transpile the code
3. Insert a json object inside this file with preset-env (transform ES6 in VanillaJS) and preset-react (understands JSX): {"presets": ["@babel/preset-env", "@babel/preset-react"]}

Building and serving with Webpack

1. Install react and react-dom to be able to run a React project: npm i react react-dom
2. Create the index.js and App.js files inside the src folder to start coding the application

index.js

import React from "react";
import ReactDOM from "react-dom";
import App from "./App";

ReactDOM.render(<App/>, document.getElementById("root"));

App.js

import React from "react";

const App = () => <div>Hello</div>;

export default App;

3. Install webpack to build and serve the project npm i --save-dev webpack webpack-cli webpack-dev-server style-loader css-loader babel-loader
4. Create a webpack.config.js file in the root directory and add:

const path = require('path');
const webpack = require('webpack');

module.exports = {
  entry: './src/index.js',
  mode: 'development',
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /(node_modules)/,
        loader: 'babel-loader',
        options: { presets: ["@babel/env"] }
      },
      {
        test: /\.css$/,
        use: ["style-loader", "css-loader"]
      }
    ]
  },
  resolve: { extensions: ['*', '.js', '.jsx'] },
  output: {
    path: path.resolve(__dirname, 'dist/'),
    publicPath: '/dist/',
    filename: 'bundle.js'
  },
  devServer: {
    contentBase: path.join(__dirname, 'public/'),
    port: 3000,
    publicPath: 'http://localhost:3000/dist/',
    hotOnly: true
  },
  plugins: [new webpack.HotModuleReplacementPlugin()]
};

5. Run the server npx webpack-dev-server --mode development. It will run in the port 3000.
6. To make it easier, add the following script in the package.json file: "dev": "npx webpack-dev-server --mode development"

React-hot-loader

1. Enable auto-reload installing react-hot-loader npm i --save-dev react-hot-loader
2. Add import {hot} from "react-hot-loader" and export default hot(module)(App) in the App.js file