1. 新建```webpack.json.js```
```javascript
module.exports = {
  entry: './src/index.js',

  output: {
    path: 'bundle',
    filename: 'bundle.js'
  },

  module: {
    loaders: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        loaders: ['react-hot', 'babel-loader']
      },
      {
        test: /\.css$/,
        loader: 'style-loader!css-loader'
      }
    ]
  }

};
```
```entry```: the start point of react app
```output```: webpack needs to know where it should output and save transformed code, we can also use ***path*** to locate the location
```modules```: we define which transformation to make on our code
> we want our react app to transpile JSX to JavaScript and ES2015 to ES5. We specify ***babel-loader*** to make webpack know to checkout the ```.babelrc``` file

2. Webpack Dev Server
Runs ```npm install --save-dev webpack-dev-server``` to install the webpack dev server

3. CSS loader
We can bundle our stylesheets into a single bundled JavaScript file via CSS loader. Simply run ```npm install --save-dev style-loader css-loader```
> the ***style-loader*** is going to embed the CSS in the bundle.js and the ***css-loader*** parses the css and applies it to the DOM.