> [Globals](../globals) / PgChannelEmitter

# Class: PgChannelEmitter

Implements event emitting/subscribing on PostgreSQL LISTEN/NOTIFY
named channels.

## Hierarchy

* EventEmitter

  ↳ **PgChannelEmitter**

## Index

### Constructors

* [constructor](PgChannelEmitter#constructor)

### Events

* [channel](PgChannelEmitter#channel)

### Properties

* [defaultMaxListeners](PgChannelEmitter#defaultmaxlisteners)
* [errorMonitor](PgChannelEmitter#errormonitor)

### Methods

* [addListener](PgChannelEmitter#addlistener)
* [emit](PgChannelEmitter#emit)
* [eventNames](PgChannelEmitter#eventnames)
* [getMaxListeners](PgChannelEmitter#getmaxlisteners)
* [listenerCount](PgChannelEmitter#listenercount)
* [listeners](PgChannelEmitter#listeners)
* [off](PgChannelEmitter#off)
* [on](PgChannelEmitter#on)
* [once](PgChannelEmitter#once)
* [prependListener](PgChannelEmitter#prependlistener)
* [prependOnceListener](PgChannelEmitter#prependoncelistener)
* [rawListeners](PgChannelEmitter#rawlisteners)
* [removeAllListeners](PgChannelEmitter#removealllisteners)
* [removeListener](PgChannelEmitter#removelistener)
* [setMaxListeners](PgChannelEmitter#setmaxlisteners)
* [listenerCount](PgChannelEmitter#listenercount)

## Constructors

### constructor

\+ **new PgChannelEmitter**(`options?`: EventEmitterOptions): [PgChannelEmitter](PgChannelEmitter)

*Inherited from [PgChannelEmitter](PgChannelEmitter).[constructor](PgChannelEmitter.md#constructor)*

#### Parameters:

Name | Type |
------ | ------ |
`options?` | EventEmitterOptions |

**Returns:** [PgChannelEmitter](PgChannelEmitter)

## Events

### channel

• **channel**(`payload`: [AnyJson](../globals#anyjson)): void

Channel listener event, occurs whenever the listening channel gets a new
payload message.

**`asmemberof`** PgChannelEmitter

#### Parameters:

Name | Type | Description |
------ | ------ | ------ |
`payload` | [AnyJson](../globals#anyjson) | event payload  |

**Returns:** void

## Properties

### defaultMaxListeners

▪ `Static` **defaultMaxListeners**: number

*Inherited from [PgChannelEmitter](PgChannelEmitter).[defaultMaxListeners](PgChannelEmitter.md#defaultmaxlisteners)*

___

### errorMonitor

▪ `Static` `Readonly` **errorMonitor**: unique symbol

*Inherited from [PgChannelEmitter](PgChannelEmitter).[errorMonitor](PgChannelEmitter.md#errormonitor)*

This symbol shall be used to install a listener for only monitoring `'error'`
events. Listeners installed using this symbol are called before the regular
`'error'` listeners are called.

Installing a listener using this symbol does not change the behavior once an
`'error'` event is emitted, therefore the process will still crash if no
regular `'error'` listener is installed.

## Methods

### addListener

▸ **addListener**(`event`: string \| symbol, `listener`: (...args: any[]) => void): this

*Inherited from [PgClient](../PgClient).[addListener](../interfaces/PgClient.md#addlistener)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |
`listener` | (...args: any[]) => void |

**Returns:** this

___

### emit

▸ **emit**(`event`: string \| symbol, ...`args`: any[]): boolean

*Inherited from [PgClient](../PgClient).[emit](../interfaces/PgClient.md#emit)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |
`...args` | any[] |

**Returns:** boolean

___

### eventNames

▸ **eventNames**(): Array\<string \| symbol>

*Inherited from [PgClient](../PgClient).[eventNames](../interfaces/PgClient.md#eventnames)*

**Returns:** Array\<string \| symbol>

___

### getMaxListeners

▸ **getMaxListeners**(): number

*Inherited from [PgClient](../PgClient).[getMaxListeners](../interfaces/PgClient.md#getmaxlisteners)*

**Returns:** number

___

### listenerCount

▸ **listenerCount**(`event`: string \| symbol): number

*Inherited from [PgClient](../PgClient).[listenerCount](../interfaces/PgClient.md#listenercount)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |

**Returns:** number

___

### listeners

▸ **listeners**(`event`: string \| symbol): Function[]

*Inherited from [PgClient](../PgClient).[listeners](../interfaces/PgClient.md#listeners)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |

**Returns:** Function[]

___

### off

▸ **off**(`event`: string \| symbol, `listener`: (...args: any[]) => void): this

*Inherited from [PgClient](../PgClient).[off](../interfaces/PgClient.md#off)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |
`listener` | (...args: any[]) => void |

**Returns:** this

___

### on

▸ **on**(`channelName`: string, `listener`: *typeof* channel): this

*Overrides void*

Sets channel listener event handler

#### Parameters:

Name | Type | Description |
------ | ------ | ------ |
`channelName` | string | channel name to listen |
`listener` | *typeof* channel | channel event handler |

**Returns:** this

___

### once

▸ **once**(`channelName`: string, `listener`: *typeof* channel): this

*Overrides [PgClient](../PgClient).[once](../interfaces/PgClient.md#once)*

Sets channel listener event handler which will be fired only one time

#### Parameters:

Name | Type | Description |
------ | ------ | ------ |
`channelName` | string | channel name to listen |
`listener` | *typeof* channel | channel event handler |

**Returns:** this

___

### prependListener

▸ **prependListener**(`event`: string \| symbol, `listener`: (...args: any[]) => void): this

*Inherited from [PgClient](../PgClient).[prependListener](../interfaces/PgClient.md#prependlistener)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |
`listener` | (...args: any[]) => void |

**Returns:** this

___

### prependOnceListener

▸ **prependOnceListener**(`event`: string \| symbol, `listener`: (...args: any[]) => void): this

*Inherited from [PgClient](../PgClient).[prependOnceListener](../interfaces/PgClient.md#prependoncelistener)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |
`listener` | (...args: any[]) => void |

**Returns:** this

___

### rawListeners

▸ **rawListeners**(`event`: string \| symbol): Function[]

*Inherited from [PgClient](../PgClient).[rawListeners](../interfaces/PgClient.md#rawlisteners)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |

**Returns:** Function[]

___

### removeAllListeners

▸ **removeAllListeners**(`event?`: string \| symbol): this

*Inherited from [PgClient](../PgClient).[removeAllListeners](../interfaces/PgClient.md#removealllisteners)*

#### Parameters:

Name | Type |
------ | ------ |
`event?` | string \| symbol |

**Returns:** this

___

### removeListener

▸ **removeListener**(`event`: string \| symbol, `listener`: (...args: any[]) => void): this

*Inherited from [PgClient](../PgClient).[removeListener](../interfaces/PgClient.md#removelistener)*

#### Parameters:

Name | Type |
------ | ------ |
`event` | string \| symbol |
`listener` | (...args: any[]) => void |

**Returns:** this

___

### setMaxListeners

▸ **setMaxListeners**(`n`: number): this

*Inherited from [PgClient](../PgClient).[setMaxListeners](../interfaces/PgClient.md#setmaxlisteners)*

#### Parameters:

Name | Type |
------ | ------ |
`n` | number |

**Returns:** this

___

### listenerCount

▸ `Static`**listenerCount**(`emitter`: EventEmitter, `event`: string \| symbol): number

*Inherited from [PgChannelEmitter](PgChannelEmitter).[listenerCount](PgChannelEmitter.md#listenercount)*

**`deprecated`** since v4.0.0

#### Parameters:

Name | Type |
------ | ------ |
`emitter` | EventEmitter |
`event` | string \| symbol |

**Returns:** number