node.js - Webpack for back-end?

Question

I was just wondering, I started using Webpack for a new project and so far it's working fine. I almost would say I like it better than Grunt, which I used before. But now I'm quite confused how and or I should use it with my Express back-end?

See, I'm creating one app with a front-end (ReactJS) and a back-end (ExpressJS). The app will be published on Heroku. Now it seems like I should use Webpack with ExpressJS as well to get the app up and running with one single command (front-end and back-end).

But the guy who wrote this blogpost http://jlongster.com/Backend-Apps-with-Webpack--Part-I seems to use Webpack for bundling all back-end js files together, which is in my opinion really not necessary. Why should I bundle my back-end files? I think I just want to run the back-end, watch my back-end files for changes and use the rest of Webpack's power just for the front-end.

How do you guys bundle the front-end but at the same time run the back-end nodejs part? Or is there any good reason to bundle back-end files with Webpack?

Answer 1

Why to use webpack on node backend

If we are talking about react and node app you can build isomorphic react app. And if you are using import ES6 Modules in react app on client side it's ok - they are bundled by webpack on the client side.

But the problem is on server when you are using the same react modules since node doesn't support ES6 Modules. You can use require('babel/register'); in node server side but it transipile code in runtime - it's not effective. The most common way to solve this problem is pack backend by webpack (you don't need all code to be transpile by webpack - only problematic, like react stuff in this example).

The same goes with JSX.

Bundling frontend and backend at the same time

Your webpack config can have to configs in array: one for frontend and second for backend:

webpack.config.js

const common = {
    module: {
        loaders: [ /* common loaders */ ]
    },
    plugins: [ /* common plugins */ ],
    resolve: {
        extensions: ['', '.js', '.jsx'] // common extensions
    }
    // other plugins, postcss config etc. common for frontend and backend
};

const frontend = {
     entry: [
         'frontend.js'
     ],
     output: {
        filename: 'frontend-output.js'
     }
     // other loaders, plugins etc. specific for frontend
};

const backend = {
     entry: [
         'backend.js'
     ],
     output: {
        filename: 'backend-output.js'
     },
     target: 'node',
     externals: // specify for example node_modules to be not bundled
     // other loaders, plugins etc. specific for backend
};

module.exports = [
    Object.assign({} , common, frontend),
    Object.assign({} , common, backend)
];

If you start this config with webpack --watch it will in parallel build your two files. When you edit frontend specific code only frontend-output.js will be generated, the same is for backend-output.js. The best part is when you edit isomorphic react part - webpack will build both files at once.

You can find in this tutorial explanation when to use webpack for node (in chapter 4).