fbjs

What is fbjs?

The fbjs package is a collection of utility libraries used by Facebook in building its JavaScript applications. It is not specifically designed for external use but offers various utilities that can be beneficial in web development, such as manipulation of DOM elements, event handling, and AJAX requests.

What are fbjs's main functionalities?

DOM Manipulation

This feature allows developers to check if one DOM element is contained within another. The function 'containsNode' from fbjs can be used to verify if a specific child node is a descendant of a given parent node.

import { containsNode } from 'fbjs/lib/containsNode';
const parent = document.getElementById('parent');
const child = document.getElementById('child');
console.log(containsNode(parent, child));

Event Handling

fbjs provides utilities for handling DOM events. The 'addEvent' function can be used to attach event listeners to DOM elements, simplifying the process of managing events.

import { addEvent } from 'fbjs/lib/EventListener';
const button = document.getElementById('myButton');
addEvent(button, 'click', function() { alert('Button clicked!'); });

AJAX Requests

The 'fetchWithRetries' function from fbjs enhances the standard fetch API by adding automatic retries for failed requests, which is particularly useful in network-unstable environments.

import { fetchWithRetries } from 'fbjs/lib/fetchWithRetries';
fetchWithRetries('https://api.example.com/data', {
  method: 'GET'
}).then(response => response.json()).then(data => console.log(data));

Other packages similar to fbjs

lodash

Lodash is a comprehensive utility library offering a wide range of functions for tasks like array manipulation, object handling, and string operations. It is more modular and generally has broader usage than fbjs, which is more tailored to Facebook's internal structure and needs.

underscore

Underscore is another utility library similar to lodash but with a slightly different API. It provides functional programming helpers without extending any built-in objects. It's comparable to fbjs in terms of providing utility functions but is more focused on functional programming.

README

FBJS

Purpose

To make it easier for Facebook to share and consume our own JavaScript. Primarily this will allow us to ship code without worrying too much about where it lives, keeping with the spirit of @providesModule but working in the broader JavaScript ecosystem.

Note: If you are consuming the code here and you are not also a Facebook project, be prepared for a bad time. APIs may appear or disappear and we may not follow semver strictly, though we will do our best to. This library is being published with our use cases in mind and is not necessarily meant to be consumed by the broader public. In order for us to move fast and ship projects like React and Relay, we've made the decision to not support everybody. We probably won't take your feature requests unless they align with our needs. There will be overlap in functionality here and in other open source projects.

Usage

Any @providesModule modules that are used by your project should be added to src/. They will be built and added to module-map.json. This file will contain a map from @providesModule name to what will be published as fbjs. The module-map.json file can then be consumed in your own project, along with the rewrite-modules Babel plugin (which we'll publish with this), to rewrite requires in your own project. Then, just make sure fbjs is a dependency in your package.json and your package will consume the shared code.

// Before transform
var emptyFunction = require('emptyFunction');
// After transform
var emptyFunction = require('fbjs/lib/emptyFunction');

See React for an example of this. Coming soon!

Building

It's as easy as just running gulp. This assumes you've also done npm install -g gulp.

gulp

Alternatively npm run build will also work.

Layout

Right now these packages represent a subset of packages that we use internally at Facebook. Mostly these are support libraries used when shipping larger libraries, like React and Relay, or products. Each of these packages is in its own directory under src/.

Process

Since we use @providesModule, we need to rewrite requires to be relative. Thanks to @providesModule requiring global uniqueness, we can do this easily. Eventually we'll try to make this part of the process go away by making more projects use CommmonJS.

TODO

• Flow: Ideally we'd ship our original files with type annotations, however that's not doable right now. We have a couple options:
  • Make sure our transpilation step converts inline type annotations to the comment format.
  • Make our build process also build Flow interface files which we can ship to npm.
• Split into multiple packages. This will be better for more concise versioning, otherwise we'll likely just be shipping lots of major versions.