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2.8.0 • Public • Published

Build Status



FEBS is an extensible Webpack-based front-end build system designed to be used by a community of front-end developers or a series of projects using a similar set of technologies in order to reduce duplicate effort on build configuration.

Its code falls into two categories

Build Features

JavaScript / Style, Source Maps, Live reloading, Code Watching, Linting, etc.

FEBS core

Learn more about REI's Front-End Build System by checking out the introductory post on the REI Co-op Engineering blog

Getting Started


Install the dependency

npm install --save @rei/febs

Assign build tasks

FEBS exposes an executable named febs to be used within the scripts of your package.json

"scripts": {
  "build": "NODE_ENV=prod febs prod",
  "dev": "NODE_ENV=dev febs dev --no-dev-server",
  "live-reload": "NODE_ENV=dev febs dev"
  "watch": "NODE_ENV=dev febs dev --no-dev-server --watch"

There is some work to remove the requirement on NODE_ENV and give full respect to the second argument.

Update or use defaults to specify paths for the CSS and JS you want to compile and run


npm run build - Uses the Production build task

npm run dev - Uses the Development build task

npm run live-reload - Uses the Live reloading feature

npm run watch - Uses the Code watching feature

See Command-line Interface for more details and additional ways to run.

Default Configuration

Entry points

  • Default JavaScript entry point: /src/js/entry.js
  • Default Style entry point: /src/style/entry.css

Output path

  • Bundles written to: /dist/<packageName>/.

Given the above defaults, FEBS will generate two bundles at the following paths:


You can adjust these default configurations using the febs configuration

Build Features


@TODO: additional detail


@TODO: additional detail

Source Maps

@TODO: additional detail


Linting is provided via eslint

eslint will run on both JavaScript and Vue components using the .eslintrc.json that is created on febs init. This config is used by both webpack during a build and eslint at the command line so the results should be identical.

  • To run eslint at the command line: npx eslint <file/directory/etc>

  • To fix eslint errors, npx eslint --fix <file/directory/etc>

  • Currently, febs init copies over the .eslintrc.json file but in the future we'll likely be creating a shared eslint configuration used by both wp and the eslint at the command line.

  • febs is configured to return Linux compatible exit codes in order to signal to a global build tool (such as Maven) the success / failure of the front-end build. In the case of lint-only errors, we do not return an error code 1 (error) as we don't want to fail the global build due to linting errors, however, they are still reported. In the near future, this will be configurable.

Code watching

@TODO: additional detail

Live reloading

@TODO: additional detail


Command-line interface

@TODO: additional detail (npx tip)

Production and Development Builds

Production Build Task

@TODO: additional detail

Development Build Task

@TODO: additional detail

FEBS Configuration

If the default entry points / output paths don't work for you, you can specify them by using a febs-config.json file next to your package.json that is using febs.

Here is an example of a entry / output configuration that might be made to use a more Java / Maven like file structure.


  "entry": {
    "details": [
    "details-reviews": [
  "output": {
    "path": "./target/classes/dist"

entry property

In the febs-config.json example above we are creating our own entry points, instead of using the defaults. We specify the path where our JavaScript and styles live.

output property

In the febs-config.json example above we change the default output path to the Java classpath where a Java asset injector will be able to read for injection.

Example configuration output

Given the above example, FEBS will generate two bundles at the following paths:

  • details.1234.js will only contain JavaScript contained in entry.js (including its dependencies)

  • details-reviews.1234.js will bundle reviews.js and write-review.js files into one bundle

If you'd like to further configure FEBS, you can look at the webpack overrides

Webpack Overrides

FEBS uses Webpack to build and is providing a default Webpack configuration under the hood.

You can override or create new configurations through webpack directly where necessary. If you think others might need the override please file a ticket or reach out for support. Where you can, attempt to avoid using this feature to reduce duplication of work.

To customize your build, creating a webpack.overrides.conf.js at the root of your npm package. Anything that Webpack understands is fair game for the overrides file. Want to add a loader or a plugin?

// Webpack.overrides.conf.js
module.exports = {
  module: {
    rules: [{
      test: '/\.js$/'
      use: {
        loader: 'cool-js-loader'
  plugins: [
    new CoolPlugin()

You can find out all of the Webpack defaults by reviewing the base Webpack configuration file.

Additional Concepts

Build Manifest

A manifest.json is built to ./dist/<packageName>/manifest.json. This is a mechanism to be used by an asset injector to insert assets onto a page.

@TODO: Additional detail

Asset Injector

An asset injector uses a manifest.json to insert production assets into the markup of a webpage.

See our example JavaScript implementation of the an asset injector. One could create one to be used by Thymleaf, Freemarker, JSP Tags, Vue, React, Mustache, Handlebars, etc.

@TODO: publish JavaScript implementation and asset pipeline architectural diagrams and relate to an "asset pipeline".

Project Information

Release management

The project strictly use semver.

The main thing to call out here is that if maintainers (intentionally) introduce an incompatible Webpack configuration change, the major version is bumped. When the project moves from Webpack 3 to 4, the major version is bumped.

If the project unintentionally introduces a new bug through a change through febs core or build features, there will be a prompt fix. Additionally, maintainers will continue to improve our unit and functional testing strategies and bug response times.

Somewhat related, the intention is to move the Webpack configuration to a separate repository and have that be configurable. At that point the project can have more fine-grained release management and flexibility as well as allow non-internal customers to have complete control over their shared base configuration.


When something gets deprecated, it will not be supported in the next major release but will continue to get supported for the previous version.


The project focus is around FEBS core. For Build Features it should be look at as community of practice effort, this is one of the main ideas. However, a maintainer should be a major contributor to features.

For our internal customers: Think of FEBS as just a base Webpack config that you can edit that happens to be in a different repository

Maintainers support one major version behind and attempt to minimize and group up major version releases to reduce upgrade/support burden.

Internal open source customers

We fully support our internal customers. That means we will respond to Slack messages and help troubleshoot issues, feature requests, etc.

Feel free to swing by or hit us up on Slack in the #febs-users channel or just file an issue here :)

External open source customers

Maintainers will respond to Github issues within a week for issues with FEBS core. Unfortunately, there are no guarantees for "immediate" support due to bandwidth. However, we are happy to collaborate and work together on pull requests. You are very much welcome and encouraged to fork this project and see where it goes.

Also, we'd love to hear your ideas and feedback on different approaches or similar solutions in the community that you think could improve FEBS.




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