Setting up reactjs development environment from scratch

Basic Tools needed to work with ReactJS are react, babel and webpack. Babel transcompiles JSX syntax into javascript syntax.

What is ReactJS ?

ReactJS is a javascript library. It is used to build web user interfaces. It is mostly used to develop single page web applications. We can also develop mobile applications using library ReactJS. To develop mobile applications we use library ReactNative.

Advantages of ReactJS

  • ReactJS a opensource library
  • ReactJS is used to build single page web applications.
  • ReactJS is component based. A webpage can be devided into simple modules called a “component”. We can build a complex component using basic components. Every component has it’s own state to respond to the events. Because component logics are writtern in javascript.
  • ReactJs uses a virtual DOM to speed up the rendering process.
  • Code re-usability is a must in Software Development. In web development most of the functionality is repeated. So, we can reuse the components.
  • ReactJS uses ES06 javasxript syntax called as JSX. It speeds up the ReactJS appliations development time. JSX is a advanced javascript syntax.

Install NodeJS and NPM

Nodejs is a cross platform javascript runtime environment. It’s capable of executing the javascript code server-side. It is used with ReactJS to run the react development server. NPM(node package manager) is a manager of javascript packages. By using it we can install javascript packages required for our project. It’s just like python pip.

To install NodeJS and NPM on ubuntu run the below commands on terminal

curl -sL | sudo -E bash -
sudo apt-get install -y nodejs
sudo npm install npm --global

Confirm installation of NodeJs and NPM

node -v
# v8.0.0
npm -v
# 6.0.0

Basic Tools needed to work with ReactJS

  1. React: To work with react we need to install it’s dependencies like react, react-dom, etc.
  2. Babel: ReactJS uses JSX syntax to speed up the development process. But the syntax is not understandable by browsers. So, we need a transcompiler (Babel) to convert JSX into a javascript code.
  3. Webpack: It is a javascript code bundler. In ReactJS we deal with the components so, every component is written in a seperate file to quickly navigate to the component and make changes. It will be difficult to add all these files to webpage. So, we use webpack to to bundle all these components.

setting up dev environment for a simple app

  1. create and navigate to the directory “react_app”
     mkdir react_app && cd react_app
  2. create a react package using command npm init. It will ask some questions either answer or just press key. It will create a file `package.json` file to manage the react app dependencies. `package.json` file looks similar to
     "name": "react_app",
     "version": "1.0.0",
     "description": "",
     "main": "index.js",
     "scripts": {
         "test": "echo \"Error: no test specified\" && exit 1"
     "author": "Agiliq",
     "license": "ISC"
  3. Now, install webpack and webpack-dev-server
    • webpack: to generate a single javascript files out of all components and host it on the dev server.
    • webpack-dev-server: it helps us to transcompile the jsx every time we make changes to any component and it loads the newly generated file onto the development server. Install it with the below command
      npm install webpack webpack-cli webpack-dev-server --save-dev
  4. install react, react-dom, babel and it’s dependencies
    npm install --save react react-dom
    npm install --save-dev babel-core babel-loader babel-preset-env babel-preset-react
    npm install --save-dev style-loader css-loader
    npm install --save-dev html-webpack-plugin
    echo '{ "presets": ["react", "env"] }' > .babelrc
    • babel-core: It transforms ES6 code into ES5
    • babel-loader: It is a webpack helper to transform the JavaScript dependencies with babel
    • babel-preset-env: It determines the plugins to use and provides modern functionality on older browsers that do not natively support it.
    • babel-preset-react: Babel preset for all React plugins, for example, turning JSX into javascript functions
    • css-loader: we import css files in JSX files, it helps to resolve them.
    • style-loader: it collects all the styles and makes it a single file and injects it into DOM.
    • html-webpack-plugin: It is needed to inject this into our DOM — adding a <style> tag into the <head> element of our HTML.
  5. We will going to create a directory structure as below for our application
         ├── src
         │   ├── components
         │   │   └── HelloWorld
         │   │       ├── HelloWorld.css
         │   │       └── HelloWorld.js
         │   ├── index.html
         │   └── index.js
         ├── .babelrc
         ├── package.json
         └── webpack.config.js
    • react_app: Root of project directory.
    • react_app/src: It contains all our react app source code.
    • react_app/src/components: It contains the components of react app.
    • react_app/src/index.html: It it used by html webpack plugin to work with react. It contains the root element which react renderer will use.
    • react_app/src/index.js: It is the entry point where react starts rendering the components.
    • .babelrc: It provide the options for babel-loader.
    • package.json: It contains the package dependency information and startup scripts to be used.
    • webpack.config.js: It contains the configuration information of webpack.

    Now, we know why we use above files. Let’s configure all these files.

  6. To configure webpack create webpack.config.js and add below code to it.
     const HtmlWebPackPlugin = require("html-webpack-plugin");
     const htmlWebpackPlugin = new HtmlWebPackPlugin({
       template: "./src/index.html",
       filename: "./index.html"
     module.exports = {
       module: {
         rules: [
             test: /\.js$/,
             exclude: /node_modules/,
             use: {
               loader: "babel-loader"
             test: /\.css$/,
             use: [
                 loader: "style-loader"
                 loader: "css-loader",
                 options: {
                   modules: true,
                   importLoaders: 1,
                   localIdentName: "[name]_[local]_[hash:base64]",
                   sourceMap: true,
                   minimize: true
       plugins: [htmlWebpackPlugin]

    Note: we can also use other plugins like scss-loader to work with it.

  7. Now, open package.json and add below start scripts to it.
     "scripts": {
         "start": "webpack-dev-server --mode development --open --port 3000",
         "build": "webpack --mode production"

    These are aliases for lengthy commands. If run command npm run start then it will run command webpack-dev-server --mode development --open --port 3000 which will opens a browser with dev host on port 3000 http://localhost:3000 For production, use command npm run build. After running the command it will creates a new directory named dist with bundled javascript, css and images.

    After adding the above code package.json looks like below

      "name": "react_app",
      "version": "1.0.0",
      "description": "",
      "main": "index.js",
      "scripts": {
     "start": "webpack-dev-server --mode development --open --port 3000",
     "build": "webpack --mode production"
      "keywords": ["react from scratch"],
      "author": "Agiliq",
      "license": "ISC",
      "devDependencies": {
     "babel-core": "^6.26.3",
     "babel-loader": "^7.1.4",
     "babel-preset-env": "^1.7.0",
     "babel-preset-react": "^6.24.1",
     "css-loader": "^0.28.11",
     "html-webpack-plugin": "^3.2.0",
     "style-loader": "^0.21.0",
     "webpack": "^4.8.3",
     "webpack-cli": "^2.1.3",
     "webpack-dev-server": "^3.1.4"
      "dependencies": {
     "react": "^16.3.2",
     "react-dom": "^16.3.2"
  8. Let’s see how other files looks like
     <html lang="en">
       <meta charset="UTF-8">
       <meta name="viewport" content="width=device-width, initial-scale=1.0">
       <meta http-equiv="X-UA-Compatible" content="ie=edge">
       <title>React App</title>
       <section id="main"></section>


     import React from "react";
     import ReactDOM from "react-dom";
     import Hello from "./components/HelloWorld/HelloWorld"
     ReactDOM.render(<Hello />, document.getElementById("main"));


     import React from "react";
     import style from "./HelloWorld.css";
     const HelloWorld = () => {
       return (<div className={style.Hello}>
     module.exports = HelloWorld;


         font-size: 100px;
         color: green;

Now, open your terminal and change directory to react_app and run the command npm run start. It will open browser with url http://localhost:3000. You can find text Hello world with font size 100px with green color. When we run command npm run start or webpack-dev-server --mode development --open --port 3000 webpack runs the dev server using the configuration file webpack.config.js and starts execution from file index.js because index.js pointed in package.json

To test it let’s change the text in HelloWorld component to "Hello Agiliq".

Stay tuned for our next post “Understanding State and Props in ReactJS”

Thank you for reading the Agiliq blog. This article was written by Anjaneyulu Batta on May 23, 2018 in javascriptreactjsdev-environmentfrom scratch .

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