# Storybook Channel

Storybook Channel is similar to an EventEmitter.
Channels are used with Storybook implementations to send/receive events between the Storybook Manager and the Storybook Renderer.

```js
class Channel {
  addListener(type, listener) {}
  addPeerListener(type, listener) {} // ignore events from itself
  emit(type, ...args) {}
  eventNames() {}
  listenerCount(type) {}
  listeners(type) {}
  on(type, listener) {}
  once(type, listener) {}
  prependListener(type, listener) {}
  prependOnceListener(type, listener) {}
  removeAllListeners(type) {}
  removeListener(type, listener) {}
}
```

The channel takes a Transport object as a parameter which will be used to send/receive messages. The transport object should implement this interface.

```js
class Transport {
  send(event) {}
  setHandler(handler) {}
}
```

Currently, channels are baked into storybook implementations and therefore this module is not designed to be used directly by addon developers. When developing addons, use the `getChannel` method exported by `@storybook/addons` module. For this to work, Storybook implementations should use the `setChannel` method before loading addons.

```js
import { addons } from '@storybook/addons';

const channel = addons.getChannel();
```

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For more information visit: [storybook.js.org](https://storybook.js.org)
