https://webpack.js.org/guides/getting-started/

    npm init -y
    npm install webpack webpack-cli —save-dev
    npm install —save lodash

    1. webpack-demo
    2. |- package.json
    3. |- webpack.config.js
    4. |- /dist
    5.   |- main.js
    6.   |- index.html
    7. |- /src
    8.   |- index.js
    9. |- /node_modules
    1. <!-- /dist/index.html --> 
    2. <!doctype html>
    3.   <html>
    4.    <head>
    5.      <title>Getting Started</title>
    6.    </head>
    7.    <body> 
    8.     <script src="main.js"></script>
    9.    </body>
    10.   </html>
    1. // /webpack.config.js
    2. const path = require('path');
    4. module.exports = {
    5.   entry: './src/index.js',
    6.   output: {
    7.     filename: 'main.js',
    8.     path: path.resolve(__dirname, 'dist')
    9.   }
    10. };
    1. // /index.js
    2. import _ from 'lodash';
    4. function component() {
    5.   let element = document.createElement('div');
    6.   element.innerHTML = _.join(['Hello', 'webpack'], ' ');
    7.   return element;
    8. }
    10. document.body.appendChild(component());

    控制台，执行webpack
    会自动生成dist文件夹，index.html页面要手动拷贝进去
    会从src中找到index.js然后“通过加工”在dist文件夹中自动生成main.js，需要你配置加载器，就会对js进行加工了