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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 of build configurations.

Its code falls into two categories:

Build Features

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


Confirm that you satisfy the minimum node.js version.


Install the dependency

npm install --save @rei/febs core-js@^3.1.x

Assign build tasks

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

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

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

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.less

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



Source Maps

Source maps are generated for your bundles via the following webpack methods:

  • dev: eval-source-map
  • prod: source-map


As FEBS is responsible only for building your code, it does not provide for linting. You should implement a linting step per your style guide as a separate npm task in your package.json.

Code watching

To enable code watching, run:

febs dev --no-dev-server --watch

Live reloading

@TODO: additional detail


Command-line interface

FEBS provides a simple command-line interface.

Production and Development Builds

Production Build Task

febs prod

Development Build Task

febs dev
febs dev -no-dev-server
febs dev --no-dev-server --watch

Unless no-dev-server is specified, febs will use webpack-dev-server to create an express server on port 8080. If that port is already in use, an open port will be found and displayed in the terminal.

FEBS Configuration

If the default entry/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 entry/output paths using a typical Java/Maven-like project directory structure.


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


  • the febs-config.json overrides the webpack.overrides.config.js file. (i.e., if entry and output are specified in both, the build will use the entries in febs-config.json.
  • the entry/output paths are resolved relative to npm root.
  • the output path is appended with <package name>, i.e., dist/details/. Use the overrides file if you want to specify a unique path.

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.

Note: The entry paths are specified relative to npm root directory.

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.


  • The output paths are specified relative to npm root directory.
  • the output path is appended with <package name>, i.e., dist/<package name>/. Use the overrides file if you want to specify a unique path.

ssr property

This value determines whether or not to build the vue-ssr-server-bundle.json required for server-side rendering.


  • Enabling this will add additional time to the build as it essentially needs to run 2 builds, one for the client and one for the server. Additionally, the generated vue-ssr-server-bundle.json is very large.
  • This is automatically disabled during development builds, i.e., febs dev.

Example configuration output

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

./target/classes/dist/<package name>/details.1234.js
./target/classes/dist/<package name>/detail-reviews.1234.js
  • 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

You may also configure additional loaders and update your input/output entries in a local file called webpack.overrides.conf.js (See below example).

If you do need an override, consider opening a PR to get this pulled into the base config or reach out to support. By doing so, we can all benefit from your overrides and prevent others from needing to duplicate the same overrides.

// 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 config.

Additional Concepts

Build Manifest

A febs-manifest.json is built to the output directory. 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 febs-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 Thymeleaf, 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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