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ModuleClient class

Package:
azure-iot-device

IoT Hub device client used to connect a device with an Azure IoT hub.

Users of the SDK should call one of the factory methods, fromConnectionString or fromSharedAccessSignature to create an IoT Hub device client.

Extends

InternalClient

Methods

close()
close(Callback<Disconnected>)

Closes the transport connection and destroys the client resources.

Note: After calling this method the ModuleClient object cannot be reused.
fromAuthenticationProvider(AuthenticationProvider, any)

Creates an IoT Hub module client from the given authentication method and using the given transport type.
fromConnectionString(string, any)

Creates an IoT Hub device client from the given connection string using the given transport type.
fromEnvironment(any)
fromEnvironment(any, Callback<ModuleClient>)

Creates an IoT Hub module client by using configuration information from the environment.

If an environment variable called EdgeHubConnectionString or IotHubConnectionString exists, then that value is used and behavior is identical to calling fromConnectionString passing that in. If those environment variables do not exist then the following variables MUST be defined:

- IOTEDGE_WORKLOADURI          URI for iotedged's workload API
- IOTEDGE_DEVICEID             Device identifier
- IOTEDGE_MODULEID             Module identifier
- IOTEDGE_MODULEGENERATIONID   Module generation identifier
- IOTEDGE_IOTHUBHOSTNAME       IoT Hub host name
- IOTEDGE_AUTHSCHEME           Authentication scheme to use; must be "sasToken"
fromSharedAccessSignature(string, any)

Creates an IoT Hub module client from the given shared access signature using the given transport type.
invokeMethod(string, MethodParams)
invokeMethod(string, MethodParams, Callback<MethodResult>)

Invokes a method on a downstream device or on another module on the same IoTEdge device. Please note that this feature only works when the module is being run as part of an IoTEdge device.
invokeMethod(string, string, MethodParams)
invokeMethod(string, string, MethodParams, Callback<MethodResult>)
onMethod(string, DoubleValueCallback<DeviceMethodRequest, DeviceMethodResponse>)

Registers a callback for a method named methodName.
sendOutputEvent(string, Message)
sendOutputEvent(string, Message, Callback<MessageEnqueued>)

Sends an event to the given module output
sendOutputEventBatch(string, Message[])
sendOutputEventBatch(string, Message[], Callback<MessageEnqueued>)

Sends an array of events to the given module output
setOptions(DeviceClientOptions)
setOptions(DeviceClientOptions, Callback<TransportConfigured>)

Passes options to the ModuleClient object that can be used to configure the transport.

Inherited Methods

abandon(Message)
abandon(Message, Callback<MessageAbandoned>)
addListener<E>(string | symbol, (args: any[]) => void)

Alias for emitter.on(eventName, listener).
complete(Message)
complete(Message, Callback<MessageCompleted>)
emit<E>(string | symbol, any[])

Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.

Returns true if the event had listeners, false otherwise.

import { EventEmitter } from 'node:events';
const myEmitter = new EventEmitter();

// First listener
myEmitter.on('event', function firstListener() {
  console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(arg1, arg2) {
  console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...args) {
  const parameters = args.join(', ');
  console.log(`event with parameters ${parameters} in third listener`);
});

console.log(myEmitter.listeners('event'));

myEmitter.emit('event', 1, 2, 3, 4, 5);

// Prints:
// [
//   [Function: firstListener],
//   [Function: secondListener],
//   [Function: thirdListener]
// ]
// Helloooo! first listener
// event with parameters 1, 2 in second listener
// event with parameters 1, 2, 3, 4, 5 in third listener
eventNames()

Returns an array listing the events for which the emitter has registered listeners.

import { EventEmitter } from 'node:events';

const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});

const sym = Symbol('symbol');
myEE.on(sym, () => {});

console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]
getMaxListeners()

Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to events.defaultMaxListeners.
getTwin()
getTwin(Callback<Twin>)
listenerCount<E>(string | symbol, (args: any[]) => void)

Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.
listeners<E>(string | symbol)

Returns a copy of the array of listeners for the event named eventName.

server.on('connection', (stream) => {
  console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]
off<E>(string | symbol, (args: any[]) => void)

Alias for emitter.removeListener().
on<E>(string | symbol, (args: any[]) => void)

Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

server.on('connection', (stream) => {
  console.log('someone connected!');
});

Returns a reference to the EventEmitter, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
once<E>(string | symbol, (args: any[]) => void)

Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.

server.once('connection', (stream) => {
  console.log('Ah, we have our first user!');
});

Returns a reference to the EventEmitter, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
open()
open(Callback<Connected>)
prependListener<E>(string | symbol, (args: any[]) => void)

Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

server.prependListener('connection', (stream) => {
  console.log('someone connected!');
});

Returns a reference to the EventEmitter, so that calls can be chained.
prependOnceListener<E>(string | symbol, (args: any[]) => void)

Adds a one-time listener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.

server.prependOnceListener('connection', (stream) => {
  console.log('Ah, we have our first user!');
});

Returns a reference to the EventEmitter, so that calls can be chained.
rawListeners<E>(string | symbol)

Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).

import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.once('log', () => console.log('log once'));

// Returns a new Array with a function `onceWrapper` which has a property
// `listener` which contains the original listener bound above
const listeners = emitter.rawListeners('log');
const logFnWrapper = listeners[0];

// Logs "log once" to the console and does not unbind the `once` event
logFnWrapper.listener();

// Logs "log once" to the console and removes the listener
logFnWrapper();

emitter.on('log', () => console.log('log persistently'));
// Will return a new Array with a single function bound by `.on()` above
const newListeners = emitter.rawListeners('log');

// Logs "log persistently" twice
newListeners[0]();
emitter.emit('log');
reject(Message)
reject(Message, Callback<MessageRejected>)
removeAllListeners<E>(string | symbol)

Removes all listeners, or those of the specified eventName.

It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).

Returns a reference to the EventEmitter, so that calls can be chained.
removeListener<E>(string | symbol, (args: any[]) => void)

Removes the specified listener from the listener array for the event named eventName.

const callback = (stream) => {
  console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);

removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.

Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them from emit() in progress. Subsequent events behave as expected.

import { EventEmitter } from 'node:events';
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();

const callbackA = () => {
  console.log('A');
  myEmitter.removeListener('event', callbackB);
};

const callbackB = () => {
  console.log('B');
};

myEmitter.on('event', callbackA);

myEmitter.on('event', callbackB);

// callbackA removes listener callbackB but it will still be called.
// Internal listener array at time of emit [callbackA, callbackB]
myEmitter.emit('event');
// Prints:
//   A
//   B

// callbackB is now removed.
// Internal listener array [callbackA]
myEmitter.emit('event');
// Prints:
//   A

Because listeners are managed using an internal array, calling this will change the position indexes of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.

When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping') listener is removed:

import { EventEmitter } from 'node:events';
const ee = new EventEmitter();

function pong() {
  console.log('pong');
}

ee.on('ping', pong);
ee.once('ping', pong);
ee.removeListener('ping', pong);

ee.emit('ping');
ee.emit('ping');

Returns a reference to the EventEmitter, so that calls can be chained.
sendEvent(Message)
sendEvent(Message, Callback<MessageEnqueued>)
sendEventBatch(Message[])
sendEventBatch(Message[], Callback<MessageEnqueued>)
setMaxListeners(number)

By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.

Returns a reference to the EventEmitter, so that calls can be chained.
setRetryPolicy(RetryPolicy)

Sets the retry policy used by the client on all operations. The default is ExponentialBackoffWithJitter.
setTransportOptions(any)
setTransportOptions(any, Callback<TransportConfigured>)
updateSharedAccessSignature(string, Callback<SharedAccessSignatureUpdated>)
[captureRejectionSymbol](Error, string | symbol, any[])

The Symbol.for('nodejs.rejection') method is called in case a promise rejection happens when emitting an event and captureRejections is enabled on the emitter. It is possible to use events.captureRejectionSymbol in place of Symbol.for('nodejs.rejection').

import { EventEmitter, captureRejectionSymbol } from 'node:events';

class MyClass extends EventEmitter {
  constructor() {
    super({ captureRejections: true });
  }

  [captureRejectionSymbol](err, event, ...args) {
    console.log('rejection happened for', event, 'with', err, ...args);
    this.destroy(err);
  }

  destroy(err) {
    // Tear the resource down here.
  }
}

Method Details

close() 

function close(): Promise<Disconnected>

Returns

Promise<Disconnected>

close(Callback<Disconnected>)

Closes the transport connection and destroys the client resources.

Note: After calling this method the ModuleClient object cannot be reused.

function close(closeCallback?: Callback<Disconnected>)

Parameters

closeCallback

Callback<Disconnected>

Optional function to call once the transport is disconnected and the client closed.

fromAuthenticationProvider(AuthenticationProvider, any)

Creates an IoT Hub module client from the given authentication method and using the given transport type.

static function fromAuthenticationProvider(authenticationProvider: AuthenticationProvider, transportCtor: any): ModuleClient

Parameters

authenticationProvider

AuthenticationProvider

Object used to obtain the authentication parameters for the IoT hub.

transportCtor

any

Transport protocol used to connect to IoT hub.

Returns

ModuleClient

fromConnectionString(string, any)

Creates an IoT Hub device client from the given connection string using the given transport type.

static function fromConnectionString(connStr: string, transportCtor: any): ModuleClient

Parameters

connStr

string

A connection string which encapsulates "device connect" permissions on an IoT hub.

transportCtor

any

A transport constructor.

Returns

ModuleClient

fromEnvironment(any) 

static function fromEnvironment(transportCtor: any): Promise<ModuleClient>

Parameters

transportCtor

any

Returns

Promise<ModuleClient>

fromEnvironment(any, Callback<ModuleClient>)

Creates an IoT Hub module client by using configuration information from the environment.

If an environment variable called EdgeHubConnectionString or IotHubConnectionString exists, then that value is used and behavior is identical to calling fromConnectionString passing that in. If those environment variables do not exist then the following variables MUST be defined:

- IOTEDGE_WORKLOADURI          URI for iotedged's workload API
- IOTEDGE_DEVICEID             Device identifier
- IOTEDGE_MODULEID             Module identifier
- IOTEDGE_MODULEGENERATIONID   Module generation identifier
- IOTEDGE_IOTHUBHOSTNAME       IoT Hub host name
- IOTEDGE_AUTHSCHEME           Authentication scheme to use; must be "sasToken"

static function fromEnvironment(transportCtor: any, callback?: Callback<ModuleClient>)

Parameters

transportCtor

any

Transport protocol used to connect to IoT hub.

callback

Callback<ModuleClient>

Optional callback to invoke when the ModuleClient has been constructed or if an error occurs while creating the client.

fromSharedAccessSignature(string, any)

Creates an IoT Hub module client from the given shared access signature using the given transport type.

static function fromSharedAccessSignature(sharedAccessSignature: string, transportCtor: any): ModuleClient

Parameters

sharedAccessSignature

string

A shared access signature which encapsulates "device connect" permissions on an IoT hub.

transportCtor

any

Returns

ModuleClient

invokeMethod(string, MethodParams) 

function invokeMethod(deviceId: string, methodParams: MethodParams): Promise<MethodResult>

Parameters

deviceId

string

methodParams

MethodParams

Returns

Promise<MethodResult>

invokeMethod(string, MethodParams, Callback<MethodResult>)

Invokes a method on a downstream device or on another module on the same IoTEdge device. Please note that this feature only works when the module is being run as part of an IoTEdge device.

function invokeMethod(deviceId: string, methodParams: MethodParams, callback?: Callback<MethodResult>)

Parameters

deviceId

string

target device identifier

methodParams

MethodParams

parameters of the direct method call

callback

Callback<MethodResult>

optional callback that will be invoked either with an Error object or the result of the method call.

invokeMethod(string, string, MethodParams) 

function invokeMethod(deviceId: string, moduleId: string, methodParams: MethodParams): Promise<MethodResult>

Parameters

deviceId

string

moduleId

string

methodParams

MethodParams

Returns

Promise<MethodResult>

invokeMethod(string, string, MethodParams, Callback<MethodResult>) 

function invokeMethod(deviceId: string, moduleId: string, methodParams: MethodParams, callback: Callback<MethodResult>)

Parameters

deviceId

string

moduleId

string

methodParams

MethodParams

callback

Callback<MethodResult>

onMethod(string, DoubleValueCallback<DeviceMethodRequest, DeviceMethodResponse>)

Registers a callback for a method named methodName.

function onMethod(methodName: string, callback: DoubleValueCallback<DeviceMethodRequest, DeviceMethodResponse>)

Parameters

methodName

string

Name of the method that will be handled by the callback

callback

DoubleValueCallback<DeviceMethodRequest, DeviceMethodResponse>

Function that shall be called whenever a method request for the method called methodName is received.

sendOutputEvent(string, Message) 

function sendOutputEvent(outputName: string, message: Message): Promise<MessageEnqueued>

Parameters

outputName

string

message
Message

Returns

Promise<MessageEnqueued>

sendOutputEvent(string, Message, Callback<MessageEnqueued>)

Sends an event to the given module output

function sendOutputEvent(outputName: string, message: Message, callback?: Callback<MessageEnqueued>)

Parameters

outputName

string

Name of the output to send the event to

message
Message

Message to send to the given output

callback

Callback<MessageEnqueued>

Optional function to call when the operation has been queued.

sendOutputEventBatch(string, Message[]) 

function sendOutputEventBatch(outputName: string, messages: Message[]): Promise<MessageEnqueued>

Parameters

outputName

string

messages

Message[]

Returns

Promise<MessageEnqueued>

sendOutputEventBatch(string, Message[], Callback<MessageEnqueued>)

Sends an array of events to the given module output

function sendOutputEventBatch(outputName: string, messages: Message[], callback?: Callback<MessageEnqueued>)

Parameters

outputName

string

Name of the output to send the events to

messages

Message[]

callback

Callback<MessageEnqueued>

Function to call when the operations have been queued.

setOptions(DeviceClientOptions) 

function setOptions(options: DeviceClientOptions): Promise<TransportConfigured>

Parameters

options
DeviceClientOptions

Returns

Promise<TransportConfigured>

setOptions(DeviceClientOptions, Callback<TransportConfigured>)

Passes options to the ModuleClient object that can be used to configure the transport.

function setOptions(options: DeviceClientOptions, done?: Callback<TransportConfigured>)

Parameters

options
DeviceClientOptions

A DeviceClientOptions object.

done

Callback<TransportConfigured>

Optional callback to call once the options have been set.

Inherited Method Details

abandon(Message) 

function abandon(message: Message): Promise<MessageAbandoned>

Parameters

message
Message

Returns

Promise<MessageAbandoned>

Inherited From InternalClient.abandon

abandon(Message, Callback<MessageAbandoned>) 

function abandon(message: Message, abandonCallback: Callback<MessageAbandoned>)

Parameters

message
Message
abandonCallback

Callback<MessageAbandoned>

Inherited From InternalClient.abandon

addListener<E>(string | symbol, (args: any[]) => void)

Alias for emitter.on(eventName, listener).

function addListener<E>(eventName: string | symbol, listener: (args: any[]) => void): ModuleClient

Parameters

eventName

string | symbol

listener

(args: any[]) => void

Returns

ModuleClient

Inherited From InternalClient.addListener

complete(Message) 

function complete(message: Message): Promise<MessageCompleted>

Parameters

message
Message

Returns

Promise<MessageCompleted>

Inherited From InternalClient.complete

complete(Message, Callback<MessageCompleted>) 

function complete(message: Message, completeCallback: Callback<MessageCompleted>)

Parameters

message
Message
completeCallback

Callback<MessageCompleted>

Inherited From InternalClient.complete

emit<E>(string | symbol, any[])

Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.

Returns true if the event had listeners, false otherwise.

import { EventEmitter } from 'node:events';
const myEmitter = new EventEmitter();

// First listener
myEmitter.on('event', function firstListener() {
  console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(arg1, arg2) {
  console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...args) {
  const parameters = args.join(', ');
  console.log(`event with parameters ${parameters} in third listener`);
});

console.log(myEmitter.listeners('event'));

myEmitter.emit('event', 1, 2, 3, 4, 5);

// Prints:
// [
//   [Function: firstListener],
//   [Function: secondListener],
//   [Function: thirdListener]
// ]
// Helloooo! first listener
// event with parameters 1, 2 in second listener
// event with parameters 1, 2, 3, 4, 5 in third listener

function emit<E>(eventName: string | symbol, args: any[]): boolean

Parameters

eventName

string | symbol

args

any[]

Returns

boolean

Inherited From InternalClient.emit

eventNames()

Returns an array listing the events for which the emitter has registered listeners.

import { EventEmitter } from 'node:events';

const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});

const sym = Symbol('symbol');
myEE.on(sym, () => {});

console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]

function eventNames(): (string | symbol)[]

Returns

(string | symbol)[]

Inherited From InternalClient.eventNames

getMaxListeners()

Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to events.defaultMaxListeners.

function getMaxListeners(): number

Returns

number

Inherited From InternalClient.getMaxListeners

getTwin() 

function getTwin(): Promise<Twin>

Returns

Promise<Twin>

Inherited From InternalClient.getTwin

getTwin(Callback<Twin>) 

function getTwin(done: Callback<Twin>)

Parameters

done

Callback<Twin>

Inherited From InternalClient.getTwin

listenerCount<E>(string | symbol, (args: any[]) => void)

Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.

function listenerCount<E>(eventName: string | symbol, listener?: (args: any[]) => void): number

Parameters

eventName

string | symbol

The name of the event being listened for

listener

(args: any[]) => void

The event handler function

Returns

number

Inherited From InternalClient.listenerCount

listeners<E>(string | symbol)

Returns a copy of the array of listeners for the event named eventName.

server.on('connection', (stream) => {
  console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]

function listeners<E>(eventName: string | symbol): (args: any[]) => void[]

Parameters

eventName

string | symbol

Returns

(args: any[]) => void[]

Inherited From InternalClient.listeners

off<E>(string | symbol, (args: any[]) => void)

Alias for emitter.removeListener().

function off<E>(eventName: string | symbol, listener: (args: any[]) => void): ModuleClient

Parameters

eventName

string | symbol

listener

(args: any[]) => void

Returns

ModuleClient

Inherited From InternalClient.off

on<E>(string | symbol, (args: any[]) => void)

Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

server.on('connection', (stream) => {
  console.log('someone connected!');
});

Returns a reference to the EventEmitter, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a

function on<E>(eventName: string | symbol, listener: (args: any[]) => void): ModuleClient

Parameters

eventName

string | symbol

The name of the event.

listener

(args: any[]) => void

The callback function

Returns

ModuleClient

Inherited From InternalClient.on

once<E>(string | symbol, (args: any[]) => void)

Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.

server.once('connection', (stream) => {
  console.log('Ah, we have our first user!');
});

Returns a reference to the EventEmitter, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a

function once<E>(eventName: string | symbol, listener: (args: any[]) => void): ModuleClient

Parameters

eventName

string | symbol

The name of the event.

listener

(args: any[]) => void

The callback function

Returns

ModuleClient

Inherited From InternalClient.once

open() 

function open(): Promise<Connected>

Returns

Promise<Connected>

Inherited From InternalClient.open

open(Callback<Connected>) 

function open(openCallback: Callback<Connected>)

Parameters

openCallback

Callback<Connected>

Inherited From InternalClient.open

prependListener<E>(string | symbol, (args: any[]) => void)

Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

server.prependListener('connection', (stream) => {
  console.log('someone connected!');
});

Returns a reference to the EventEmitter, so that calls can be chained.

function prependListener<E>(eventName: string | symbol, listener: (args: any[]) => void): ModuleClient

Parameters

eventName

string | symbol

The name of the event.

listener

(args: any[]) => void

The callback function

Returns

ModuleClient

Inherited From InternalClient.prependListener

prependOnceListener<E>(string | symbol, (args: any[]) => void)

Adds a one-time listener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.

server.prependOnceListener('connection', (stream) => {
  console.log('Ah, we have our first user!');
});

Returns a reference to the EventEmitter, so that calls can be chained.

function prependOnceListener<E>(eventName: string | symbol, listener: (args: any[]) => void): ModuleClient

Parameters

eventName

string | symbol

The name of the event.

listener

(args: any[]) => void

The callback function

Returns

ModuleClient

Inherited From InternalClient.prependOnceListener

rawListeners<E>(string | symbol)

Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).

import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.once('log', () => console.log('log once'));

// Returns a new Array with a function `onceWrapper` which has a property
// `listener` which contains the original listener bound above
const listeners = emitter.rawListeners('log');
const logFnWrapper = listeners[0];

// Logs "log once" to the console and does not unbind the `once` event
logFnWrapper.listener();

// Logs "log once" to the console and removes the listener
logFnWrapper();

emitter.on('log', () => console.log('log persistently'));
// Will return a new Array with a single function bound by `.on()` above
const newListeners = emitter.rawListeners('log');

// Logs "log persistently" twice
newListeners[0]();
emitter.emit('log');

function rawListeners<E>(eventName: string | symbol): (args: any[]) => void[]

Parameters

eventName

string | symbol

Returns

(args: any[]) => void[]

Inherited From InternalClient.rawListeners

reject(Message) 

function reject(message: Message): Promise<MessageRejected>

Parameters

message
Message

Returns

Promise<MessageRejected>

Inherited From InternalClient.reject

reject(Message, Callback<MessageRejected>) 

function reject(message: Message, rejectCallback: Callback<MessageRejected>)

Parameters

message
Message
rejectCallback

Callback<MessageRejected>

Inherited From InternalClient.reject

removeAllListeners<E>(string | symbol)

Removes all listeners, or those of the specified eventName.

It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).

Returns a reference to the EventEmitter, so that calls can be chained.

function removeAllListeners<E>(eventName?: string | symbol): ModuleClient

Parameters

eventName

string | symbol

Returns

ModuleClient

Inherited From InternalClient.removeAllListeners

removeListener<E>(string | symbol, (args: any[]) => void)

Removes the specified listener from the listener array for the event named eventName.

const callback = (stream) => {
  console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);

removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.

Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them from emit() in progress. Subsequent events behave as expected.

import { EventEmitter } from 'node:events';
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();

const callbackA = () => {
  console.log('A');
  myEmitter.removeListener('event', callbackB);
};

const callbackB = () => {
  console.log('B');
};

myEmitter.on('event', callbackA);

myEmitter.on('event', callbackB);

// callbackA removes listener callbackB but it will still be called.
// Internal listener array at time of emit [callbackA, callbackB]
myEmitter.emit('event');
// Prints:
//   A
//   B

// callbackB is now removed.
// Internal listener array [callbackA]
myEmitter.emit('event');
// Prints:
//   A

Because listeners are managed using an internal array, calling this will change the position indexes of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.

When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping') listener is removed:

import { EventEmitter } from 'node:events';
const ee = new EventEmitter();

function pong() {
  console.log('pong');
}

ee.on('ping', pong);
ee.once('ping', pong);
ee.removeListener('ping', pong);

ee.emit('ping');
ee.emit('ping');

Returns a reference to the EventEmitter, so that calls can be chained.

function removeListener<E>(eventName: string | symbol, listener: (args: any[]) => void): ModuleClient

Parameters

eventName

string | symbol

listener

(args: any[]) => void

Returns

ModuleClient

Inherited From InternalClient.removeListener

sendEvent(Message) 

function sendEvent(message: Message): Promise<MessageEnqueued>

Parameters

message
Message

Returns

Promise<MessageEnqueued>

Inherited From InternalClient.sendEvent

sendEvent(Message, Callback<MessageEnqueued>) 

function sendEvent(message: Message, sendEventCallback: Callback<MessageEnqueued>)

Parameters

message
Message
sendEventCallback

Callback<MessageEnqueued>

Inherited From InternalClient.sendEvent

sendEventBatch(Message[]) 

function sendEventBatch(messages: Message[]): Promise<MessageEnqueued>

Parameters

messages

Message[]

Returns

Promise<MessageEnqueued>

Inherited From InternalClient.sendEventBatch

sendEventBatch(Message[], Callback<MessageEnqueued>) 

function sendEventBatch(messages: Message[], sendEventBatchCallback: Callback<MessageEnqueued>)

Parameters

messages

Message[]

sendEventBatchCallback

Callback<MessageEnqueued>

Inherited From InternalClient.sendEventBatch

setMaxListeners(number)

By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.

Returns a reference to the EventEmitter, so that calls can be chained.

function setMaxListeners(n: number): ModuleClient

Parameters

n

number

Returns

ModuleClient

Inherited From InternalClient.setMaxListeners

setRetryPolicy(RetryPolicy)

Sets the retry policy used by the client on all operations. The default is ExponentialBackoffWithJitter.

function setRetryPolicy(policy: RetryPolicy)

Parameters

policy

RetryPolicy

{RetryPolicy} The retry policy that should be used for all future operations.

Inherited From InternalClient.setRetryPolicy

setTransportOptions(any) 

function setTransportOptions(options: any): Promise<TransportConfigured>

Parameters

options

any

Returns

Promise<TransportConfigured>

Inherited From InternalClient.setTransportOptions

setTransportOptions(any, Callback<TransportConfigured>) 

function setTransportOptions(options: any, done: Callback<TransportConfigured>)

Parameters

options

any

done

Callback<TransportConfigured>

Inherited From InternalClient.setTransportOptions

updateSharedAccessSignature(string, Callback<SharedAccessSignatureUpdated>) 

function updateSharedAccessSignature(sharedAccessSignature: string, updateSasCallback?: Callback<SharedAccessSignatureUpdated>)

Parameters

sharedAccessSignature

string

updateSasCallback

Callback<SharedAccessSignatureUpdated>

Inherited From InternalClient.updateSharedAccessSignature

[captureRejectionSymbol](Error, string | symbol, any[])

The Symbol.for('nodejs.rejection') method is called in case a promise rejection happens when emitting an event and captureRejections is enabled on the emitter. It is possible to use events.captureRejectionSymbol in place of Symbol.for('nodejs.rejection').

import { EventEmitter, captureRejectionSymbol } from 'node:events';

class MyClass extends EventEmitter {
  constructor() {
    super({ captureRejections: true });
  }

  [captureRejectionSymbol](err, event, ...args) {
    console.log('rejection happened for', event, 'with', err, ...args);
    this.destroy(err);
  }

  destroy(err) {
    // Tear the resource down here.
  }
}

function [captureRejectionSymbol](error: Error, event: string | symbol, args: any[])

Parameters

error

Error

event

string | symbol

args

any[]

Inherited From InternalClient.__@captureRejectionSymbol@127