0.41.1 • Public • Published


A frontend prototyper tool for rapid prototyping of websites

Known Vulnerabilities Linux Build Status Mac Build Status Windows Build Status Coverage Status Node Version License

This is the npm that powers these Fepper prototypers:

  • Fepper Main - main distribution.
  • Fepper Base - no unnecessary assets, styles, demo website, or fp-stylus extension.
  • Fepper for Drupal - templates configured for Drupal, along with a Drupal theme built to accommodate those templates.
  • Fepper for Wordpress - templates configured for WordPress, along with a WordPress theme built to accommodate those templates.

Please consult any of the above links for documentation on getting started and on power-usage of Fepper.

Under the Hood

Minimum supported Node.js version 18.0.0

To just run a Node.js implementation of Pattern Lab, instantiate a patternlab object as follows:

const config = require('./patternlab-config.json');
const cwd = process.cwd();
const Patternlab = require('fepper/ui/core/lib/patternlab');
const patternlab = new Patternlab(config, cwd);

Fepper's Patternlab constructor recognizes a second argument (current working directory) for instantiating a patternlab object. This allows it to be instantiated from any directory within any task runner or custom application.

Fepper exposes these methods on the patternlab object:

  • build: function (options)
  • compile: function (options)
  • resetConfig: function (config)

The options argument is optional. If submitted, it must be an object whose properties are intended to override one or more properties in the config object consumed by the Patternlab constructor.

Keep in mind that configs overridden by an options argument will persist through all future operations on that Patternlab instance. In order to revert the configs back to the original configs, call resetConfig with the original configs. resetConfig will reset any number of properties submitted but will not delete any preexisting properties.

Fepper is 100% compatible with Pattern Lab PHP Mustache code. It aims to maintain parity with the PHP distribution with respect to performance and core features.

Upfront and Onscreen

Using this npm decoupled from a full Fepper project requires compiling the UI by running this line of Node.js:


The word "compile" takes on a special meaning in Fepper, referring to assembling "components" into a whole. "Build" refers to outputting patterns to be displayed by the UI.

All aspects of the UI are available for customization. For example, the toolbar can accept additions, modifications, and deletions per the needs of end-users. The UI markup is compiled by recursive, functional React calls. The recursion tree is reflected by the directory structure containing the modules which compose the UI. To override any given module, copy the directory structure leading to the module from https://github.com/electric-eloquence/fepper-npm/tree/dev/ui/core/styleguide/index/html to source/_ui/index/html, respective to your implementation. Modifications to modules in that directory will override the corresponding modules in core. Additions (so long as they are correctly nested) will also be recognized.

A working example of UI customization can be found at https://github.com/electric-eloquence/fepper-drupal/blob/dev/source/_ui/index/html/00-head/head.component.js. The Fepper for Drupal project overrides its HTML title to read "Fepper D8" instead of "Fepper". In order to do so, it has the head.component.js module nested in directories that correspond to the tags that nest the head HTML element. Both head.component.js and its nesting directories must be named similarly to their corresponding elements. .component.js indicates that the file is a module to be rendered by React. It must export properties that React.createElement() understands. The numeric prefix to 00-head orders it to precede 01-body, even though "body" precedes "head" alphabetically.

In this example, by allowing customizations in the 00-head directory separate from the core components, core updates will be respected for all components except for the HTML head.

Browser JavaScript and CSS customizations can (and should) be componentized this way as well. While a head element is unlikely to have associated scripts or styles, the UI's main element does have its scripts and styles componentized as main.js and main.css in index/html/01-body/40-main. A big advantage for this type of componentization comes when elements are renamed or deleted. When you rename or delete an element, are you absolutely sure you'll rename or delete accordingly in some far-flung, monolithic script or style file?

Alas, no one should be forced to componentize this way. Generic modifications to UI scripts can be added to source/_scripts/ui-extender.js.

Similarly, generic modifications to UI CSS can be added to source/_styles/pattern-scaffolding.css. (The file is named this way to adhere to the Pattern Lab documentation on pattern states. It should not be relied on for pattern scaffolding.)

View All markup can also be overridden by copying the .mustache files in https://github.com/electric-eloquence/fepper-npm/tree/dev/ui/core/styleguide/viewall and pasting them to source/_ui/viewall (nested correctly). Modifications will then be recognized and displayed in the UI. (No additions are allowed.) Custom View All styles can be added to source/_styles/pattern-scaffolding.css.

You will need to compile the UI in order for the browser to pick up custom changes to the UI. Within a full Fepper project, this can be accomplished with the following command:

fp ui:compile

New UI customizations will not be picked up simply by restarting Fepper.

Just the Fepper Instance

While it is recommended that you use Fepper with the Fepper CLI, and its fp command, you can alternatively instantiate a barebones Fepper instance:

const cwd = process.cwd();
const Fepper = require('fepper');
const fepper = new Fepper(cwd);

cwd must contain conf.yml, patternlab-config.json, pref.yml, and the source and public directories.

There is currently no public API for object-oriented Fepper. To express demand for one, please open an issue.




DownloadsWeekly Downloads






Unpacked Size

26.1 MB

Total Files


Last publish


  • e2tha-e
  • electric-el