• When installing a package that will be bundled into your production bundle, you should use npm install --save. If you're installing a package for development purposes (e.g. a linter, testing libraries, etc.) then you should use npm install --save-dev.

• By stating what dependencies a module needs, webpack can use this information to build a dependency graph. It then uses the graph to generate an optimized bundle where scripts will be executed in the correct order

• The import and export statements have been standardized in ES2015. They are supported in most of the browsers at this moment, however there are some browsers that don't recognize the new syntax. But don't worry, webpack does support them out of the box.

• Behind the scenes, webpack actually "transpiles" the code so that older browsers can also run it

• Note that webpack will not alter any code other than import and export statements. If you are using other ES2015 features, make sure to use a transpiler such as Babel via webpack's loader system

$ npx webpack --config webpack.config.js

• If a webpack.config.js is present, the webpack command picks it up by default. We use the --config option here only to show that you can pass a configuration of any name. This will be useful for more complex configurations that need to be split into multiple files.

• A configuration file allows far more flexibility than CLI usage. We can specify loader rules, plugins, resolve options and many other enhancements this way

• Note that within scripts we can reference locally installed npm packages by name the same way we did with npx. This convention is the standard in most npm-based projects because it allows all contributors to use the same set of common scripts

• Custom parameters can be passed to webpack by adding two dashes between the npm run build command and your parameters, e.g. npm run build -- --color.

• In order to import a CSS file from within a JavaScript module, you need to install and add the style-loader and css-loader to your module configuration

module: {
    rules: [
      {
        test: /\.css$/i,
        use: ['style-loader', 'css-loader'],
      },
    ],
  },

• The above order of loaders should be maintained: 'style-loader' comes first and followed by 'css-loader'. If this convention is not followed, webpack is likely to throw errors

• webpack uses a regular expression to determine which files it should look for and serve to a specific loader. In this case, any file that ends with .css will be served to the style-loader and the css-loader.