Faces of Webpack

Łukasz Kiełczykoski

This post is not a tutorial of Webpack. It is more of a reference or directions for me and for you (I hope). Below you can find some blogposts about Webpack as well as some conference talks and cookbooks. After that, I want to get my head around connecting Rails and Webpack together in “all in with Webpack” approach.

Let’s begin…

Beginner steps

My experience with Webpack is equal zero. I had known what is it, but I had never used it. That is why I started looking for some beginner guides.

But before any reading, below you can watch a great talk by Pete Hunt who worked for Instagram at the time. The talk will show you successful usage of Webpack, the real world example (a quite popular one) and also reasons why they switched to fairly new solution.

The talk shows more advanced configuration, but it will warm you up for some reading below!

Next up, I advise you to read Nader’s post. He shows basic commands Webpack offers and he explains step by step how to build your first basic config along with an explanation of used attributes.

At this point, some of the concepts from Pete Hunt’s talk can clarify.

Yet, one thing is bugging me. I had a problem with webpack-dev-server. Everything was working. Webpack was bundling my files and browser outputed what it suppose to, but webpack-dev-server didn’t work when I wanted use presets. It shouted at me that there are any react or es2015 presets, even if everything had been installed (I mean it).

If you think somethink will work out of the box, it probably will not.

  • Paulo Programmero

Maybe I did something stupid or I’m not aware of some step. I have no idea… If you had the same problem and you solved it, please let me know in the comments.

I know what Webpack is and that’s enough!

Pete Hunt started a repo, which is in a form of a cookbook. It lets you pick up some configuration, apply to yours and you are ready to go. This will work as summary of the talk above.

Spliting up your app - chunks and styles

Now, if you need more than putting js files into single bundle, this section is for you. Below you can watch another talk, but this time it contains more advanced topics like bundling your files into several bundles - chunks, and extracting common modules into separate chunk.

As a summary, here and here are two posts written by the speaker.

I will test it and check if it is a good fit for me. Probably, there will be some post about it.

The all in

Here you can find a great article / tutorial about Webpack and how to use it with Rails. It is long, but it shows a lot.

The first thing I liked was moving your javscript files to a different folder rather than to assets/javascripts. The author proposed frontend/javascripts and the previous one should be for Webpack’s output. Then, we put assets/javascripts folder to .gitignore. Of course, there’s other way - putting everything together, but bundled output would be mixed up with our whole frontend. In my opinion, author’s view seems interesting and worth of trying and this is what I’m going to do.

There is one section that I’d like to focus on - Using webpack in production. I want to clarify for myself why I need those steps.

First of all, I read The Asset Pipeline Guide. At this point, a sort of poor understanding of steps in mentioned blogpost, turned out to be more clear now. Digesting, fingerprinting, caching, in one hand I knew about these things, but because Rails provides them out of the box I’ve never thought about manually doing them and what actually is happening in there.

We could let Sprockets to take care of Webpack’s bundles as well, but we are all in, remember?

Sprockets in order to being able to figure out the real filename of our fingerprinted bundles, creates a manifest file, which is a json file containing the real name and generated digest. To create Webpack’s manifest file the author created a rake task for that purpose which is convenient and clean. However, without proper configuration within Rails files, an app won’t use it (the manifest).

Then, the author creates some helpers to actually make the files available for browser.

I don’t know how about you, but I feel pretty amazed by this. That amazement shows I can’t take everything for granted…


When I wanted to write a post about Webpack, I had a vision of just a guide, few steps - how to start and where to move on. But, after diving more into some advanced Webpack’s freatures, I knew that I have to write not only a guide, but a little discussion with myself for myself. You see, Rails was created having in mind fast development, convenience and above all - convention over configuration. As far as I’m concerned, this caused a little bit of ignorance among developers. However, this is understandable. We can’t know everything, can we?.

It turned out for me that Webpack has more than one face. In one hand, the basic config is simple, which allows us start quickly, but then if we want more advanced configuration, it requires more awareness. In fact, isn’t it actually perfect?

Share with me your experience with Webpack and / or other thoughts.