HORIZON PROJECT

# Emitter [![Build Status](https://travis-ci.org/component/emitter.png)](https://travis-ci.org/component/emitter)

  Event emitter component.

## Installation

```

$ component install component/emitter

```

## API

### Emitter(obj)

  The `Emitter` may also be used as a mixin. For example

  a "plain" object may become an emitter, or you may

  extend an existing prototype.

  As an `Emitter` instance:

```js

var Emitter = require('emitter');

var emitter = new Emitter;

emitter.emit('something');

```

  As a mixin:

```js

var Emitter = require('emitter');

var user = { name: 'tobi' };

Emitter(user);

user.emit('im a user');

```

  As a prototype mixin:

```js

var Emitter = require('emitter');

Emitter(User.prototype);

```

### Emitter#on(event, fn)

  Register an `event` handler `fn`.

### Emitter#once(event, fn)

  Register a single-shot `event` handler `fn`,

  removed immediately after it is invoked the

  first time.

### Emitter#off(event, fn)

  * Pass `event` and `fn` to remove a listener.

  * Pass `event` to remove all listeners on that event.

  * Pass nothing to remove all listeners on all events.

### Emitter#emit(event, ...)

  Emit an `event` with variable option args.

### Emitter#listeners(event)

  Return an array of callbacks, or an empty array.

### Emitter#hasListeners(event)

  Check if this emitter has `event` handlers.

## License

MIT