# nanobus

> Tiny message bus

Latest version **4.5.0** (published 2021-02-18) · MIT license · 0 weekly downloads

## Install

```sh
npm install nanobus
pnpm add nanobus
yarn add nanobus
bun add nanobus
```

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 4.5.0 |
| Published | 2021-02-18 |
| First published | 2017-02-13 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 3 |
| Unpacked size | 23 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 228 |
| Maintainers | benlyn, s3ththompson, substack, yoshuawuyts, bret, lrlna, yerkopalma, juliangruber, timwis, ahdinosaur, toddself, sethvincent, maxogden, shama, freeman-lab, feross, emilbayes, colingourlay, jameskyburz, almost, slaskis, ungoldman, graforlock, tornqvist, amongiants, goto-bus-stop, mafintosh |
| Keywords | emit, event |

## Links

- npm: https://www.npmjs.com/package/nanobus
- Repository: https://github.com/choojs/nanobus
- Homepage: https://github.com/choojs/nanobus#readme
- Issues: https://github.com/choojs/nanobus/issues
- npm.io page: https://npm.io/package/nanobus

## Dependencies (3)

- [nanoassert](https://npm.io/package/nanoassert.md) ^1.1.0
- [nanotiming](https://npm.io/package/nanotiming.md) ^7.2.0
- [remove-array-items](https://npm.io/package/remove-array-items.md) ^1.0.0

## Alternatives

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- [@dashersw/axon](https://npm.io/package/@dashersw/axon.md) — 934 weekly downloads

## Recent versions

- 4.5.0 (latest) — 2021-02-18
- 4.4.0 — 2018-12-13
- 4.3.5 — 2018-10-28
- 4.3.4 — 2018-09-08
- 4.3.3 — 2018-02-13
- 4.3.2 — 2018-01-08
- 4.3.1 — 2017-11-14
- 4.3.0 — 2017-10-30
- 4.2.0 — 2017-06-18
- 4.1.0 — 2017-05-30
- 4.0.0 — 2017-05-20
- 3.3.0 — 2017-05-20
- 3.2.1 — 2017-05-08
- 3.2.0 — 2017-05-08
- 3.1.0 — 2017-04-18
- … 10 more at https://npm.io/package/nanobus/versions

## README

# nanobus [![stability][0]][1]
[![npm version][2]][3] [![build status][4]][5] [![test coverage][6]][7]
[![downloads][8]][9] [![js-standard-style][10]][11]

Tiny message bus.

## Usage
```js
var nanobus = require('nanobus')
var bus = nanobus()

bus.on('foo', function (color) {
  console.log('color is', color)
})

bus.emit('foo', 'blue')
```

## FAQ
### Why not use the Node API?
We had the requirement for a `*` event to catch all calls, and figured we could
improve the file size at the same time. This library is about 1/3rd the size of
Node's version. And it was easy to build, so yeah good enough of an excuse hah.

### How do I listen for replies?
You can do this by using the `.once()` listener and establishing a convention
around naming schemas.

```js
bus.on('foo', function (color) {
  console.log('foo called')
  bus.emit('foo:res')
})

bus.once('foo:res', function () {
  console.log('response received')
})
bus.emit('foo')
```

### When shouldn't I use this package?
If you're only writing code that runs inside Node and don't need a `'*'`
listener, consider using the built-in event emitter API instead.

### Are the emitters asynchronous?
No. If you're interested in doing that, use something like
[nanotick](https://github.com/yoshuawuyts/nanotick) to batch events and ensure
they run asynchronously.

## API
### `bus = nanobus([name])`
Create a new `nanobus` instance. Optionally takes a name that will be used for
tracing in the browser using the `performance.mark` / `performance.measure`
API.

### `bus.emit(eventName, [data])`
Emit an event. Arbitrary data can optionally be passed as an argument. `'*'`
listeners run after named listeners.

### `bus.on(eventName, listener([data]))`
### `bus.addListener(eventName, listener([data]))`
Listen to an event. If the event name is `'*'` the listener signature is
`listener(eventName, [data], [performanceTimingId])`.

### `bus.prependListener(eventName, listener([data]))`
Listen to an event, but make sure it's pushed to the start of the listener
queue. If the event name is `'*'` the listener signature is
`listener(eventName, [data])`.

### `bus.once(eventName, listener([data]))`
Listen to an event, and clear it after it's been called once.  If the event
name is `'*'` the listener signature is
`listener(eventName, [data], [performanceTimingId])`.

### `bus.prependOnceListener(eventName, listener([data]))`
Listen to an event, and clear it after it's been called once.  If the event
name is `'*'` the listener signature is `listener(eventName, [data])`.

### `bus.removeListener(eventName, listener)`
Remove a specific listener to an event.

### `listeners = bus.listeners(eventName)`
Return all listeners for a given event. `'*'` listeners are not included in
this list. Use `bus.listeners('*')` to get a list of `'*'` listeners.

### `bus.removeAllListeners([eventName])`
Remove all listeners to an event. If no event name is passed, removes all
listeners on the message bus. `'*'` listeners are not removed unless
`eventName` is `*` or no event name is passed.

## TypeScript

Optional event typing is available in TypeScript by passing an object type with 
event names as keys and event listener function signatures as values.

```ts
// if compilerOptions.esModuleInterop = true
import Nanobus from "nanobus"
// else
import Nanobus = require("nanobus") 

type Events = {
    foo: (color: string) => void
    bar: (count: number) => void
}

const bus = new Nanobus<Events>()

bus.on("foo", color => {
    // color: string
    console.log("color is", color)
})

bus.on("bar", count => {
    // count: number
    console.log("count is", count)
})

bus.on("*", (eventName, data) => {
    // eventName: "foo" | "bar"
    // data: any[]
    if (eventName === "foo") {
        const [color] = data as Parameters<Events["foo"]>
        // color: string
    } else if (eventName === "bar") {
        const [count] = data as Parameters<Events["bar"]>
        // count: number
    }
})

bus.emit("foo", "blue")  // required arguments: [string]
bus.emit("bar", 100)  // required arguments: [number]
```

## License
[MIT](https://tldrlegal.com/license/mit-license)

[0]: https://img.shields.io/badge/stability-experimental-orange.svg?style=flat-square
[1]: https://nodejs.org/api/documentation.html#documentation_stability_index
[2]: https://img.shields.io/npm/v/nanobus.svg?style=flat-square
[3]: https://npmjs.org/package/nanobus
[4]: https://img.shields.io/travis/choojs/nanobus/master.svg?style=flat-square
[5]: https://travis-ci.org/choojs/nanobus
[6]: https://img.shields.io/codecov/c/github/choojs/nanobus/master.svg?style=flat-square
[7]: https://codecov.io/github/choojs/nanobus
[8]: http://img.shields.io/npm/dm/nanobus.svg?style=flat-square
[9]: https://npmjs.org/package/nanobus
[10]: https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat-square
[11]: https://github.com/feross/standard

---
_Source: https://npm.io/package/nanobus · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._