# Bacon.js — Functional Reactive Programming for JavaScript

> Handle complex event streams and asynchronous data flows with a composable reactive programming library for the browser and Node.js.

## Install

Save in your project root:

# Bacon.js — Functional Reactive Programming for JavaScript

## Quick Use
```bash
npm install baconjs
```
```javascript
const Bacon = require("baconjs")
// Create an event stream from DOM clicks
const clicks = Bacon.fromEvent(document.querySelector("#btn"), "click")
// Transform and subscribe
clicks
  .map(() => new Date().toISOString())
  .onValue(time => console.log("Clicked at:", time))
```

## Introduction
Bacon.js is a functional reactive programming (FRP) library for JavaScript that models asynchronous events as composable streams and properties. It provides a declarative way to handle complex event logic, replacing tangled callback chains with clean, testable data flow pipelines.

## What Bacon.js Does
- Represents event sequences as EventStreams and time-varying values as Properties
- Provides operators to map, filter, combine, merge, and throttle streams
- Handles async operations with flatMap, retry, and error propagation
- Integrates with DOM events, Node.js EventEmitters, Promises, and callbacks
- Supports lazy evaluation so unused stream branches carry no overhead

## Architecture Overview
Bacon.js models two core abstractions: EventStream (a series of discrete events over time) and Property (a value that changes over time and always has a current value). Both support the same composable operators. The library uses a push-based evaluation model where events propagate through the operator graph. Subscriptions manage lifecycle, and streams are garbage-collected when all subscribers unsubscribe.

## Self-Hosting & Configuration
- Install from npm: `npm install baconjs`
- Import the full library or use tree-shakable ESM imports for smaller bundles
- No configuration file needed; the library is stateless and side-effect-free
- Works in browsers via bundlers (webpack, Rollup, Vite) and in Node.js directly
- TypeScript definitions are included in the package

## Key Features
- Clean separation between EventStreams and Properties
- Rich combinator library: merge, zip, combine, sampledBy, and debounce
- Built-in error handling through the stream pipeline
- Bus class for imperative event injection when bridging non-FRP code
- Works with any UI framework or vanilla JavaScript

## Comparison with Similar Tools
- **RxJS** — larger API surface with more operators and scheduler support; Bacon.js is simpler with its EventStream/Property distinction
- **Most.js** — focused on performance with a monadic API; Bacon.js prioritizes readability
- **Kefir** — inspired by Bacon.js with a lighter footprint and similar API
- **Solid.js signals** — fine-grained reactivity for UI; Bacon.js is a general-purpose FRP library

## FAQ
**Q:** How does Bacon.js differ from RxJS?
A: Bacon.js distinguishes EventStreams from Properties (time-varying values), while RxJS uses Observables for both. Bacon's API is smaller and more opinionated.

**Q:** Is Bacon.js suitable for production?
A: Yes. It has been used in production applications for over a decade and has a stable API.

**Q:** Does it support TypeScript?
A: Yes. TypeScript type definitions ship with the npm package.

**Q:** What is the bundle size?
A: The full library is about 18 KB gzipped. Tree-shaking reduces this when using ESM imports.

## Sources
- https://github.com/baconjs/bacon.js
- https://baconjs.github.io/

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Source: https://tokrepo.com/en/workflows/asset-dfe99632
Author: AI Open Source