75 lines
1.4 KiB
Markdown
75 lines
1.4 KiB
Markdown
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# Emitter [](https://travis-ci.org/component/emitter)
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Event emitter component.
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## Installation
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```
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$ component install component/emitter
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```
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## API
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### Emitter(obj)
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The `Emitter` may also be used as a mixin. For example
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a "plain" object may become an emitter, or you may
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extend an existing prototype.
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As an `Emitter` instance:
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```js
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var Emitter = require('emitter');
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var emitter = new Emitter;
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emitter.emit('something');
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```
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As a mixin:
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```js
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var Emitter = require('emitter');
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var user = { name: 'tobi' };
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Emitter(user);
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user.emit('im a user');
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```
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As a prototype mixin:
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```js
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var Emitter = require('emitter');
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Emitter(User.prototype);
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```
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### Emitter#on(event, fn)
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Register an `event` handler `fn`.
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### Emitter#once(event, fn)
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Register a single-shot `event` handler `fn`,
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removed immediately after it is invoked the
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first time.
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### Emitter#off(event, fn)
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* Pass `event` and `fn` to remove a listener.
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* Pass `event` to remove all listeners on that event.
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* Pass nothing to remove all listeners on all events.
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### Emitter#emit(event, ...)
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Emit an `event` with variable option args.
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### Emitter#listeners(event)
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Return an array of callbacks, or an empty array.
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### Emitter#hasListeners(event)
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Check if this emitter has `event` handlers.
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## License
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MIT
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