simple-tcp-to-wss - v1.0.0
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    Class SocketServer

    WebSocket 서버 클래스로, TCP 서버와의 연결을 중계하고 클라이언트 연결을 관리합니다.

    const server = new SocketServer();

    server.on('clientConnected', ({ clientId, ip }) => {
    logger.log(`New client connected: ${clientId} from ${ip}`);
    });

    // 서버 종료
    server.shutdown();

    Hierarchy

    • EventEmitter
      • SocketServer
    Index

    Constructors

    Properties

    clients: Map<string, SocketClient> = ...
    debugMode: boolean = true
    eventThrottles: Map<string, { lastBroadcast: number; throttleMs: number }> = ...
    intervals: Map<string, Timeout> = ...
    latestTcpData: any = null
    maxTcpReconnectAttempts: number = 5
    nextSubscriptionId: number = 1
    pingInterval: Timeout = null
    pingPongInterval: Timeout = null
    subscriptions: Map<string, Subscription> = ...
    tcpBroadcastTimer: Timeout = null
    tcpClient: Socket = null
    tcpReconnectAttempts: number = 0
    tcpReconnectInterval: Timeout = null
    wss: WebSocketServer
    captureRejections: boolean

    Value: boolean

    Change the default captureRejections option on all new EventEmitter objects.

    v13.4.0, v12.16.0

    captureRejectionSymbol: typeof captureRejectionSymbol

    Value: Symbol.for('nodejs.rejection')

    See how to write a custom rejection handler.

    v13.4.0, v12.16.0

    defaultMaxListeners: number

    By default, a maximum of 10 listeners can be registered for any single event. This limit can be changed for individual EventEmitter instances using the emitter.setMaxListeners(n) method. To change the default for allEventEmitter instances, the events.defaultMaxListeners property can be used. If this value is not a positive number, a RangeError is thrown.

    Take caution when setting the events.defaultMaxListeners because the change affects all EventEmitter instances, including those created before the change is made. However, calling emitter.setMaxListeners(n) still has precedence over events.defaultMaxListeners.

    This is not a hard limit. The EventEmitter instance will allow more listeners to be added but will output a trace warning to stderr indicating that a "possible EventEmitter memory leak" has been detected. For any single EventEmitter, the emitter.getMaxListeners() and emitter.setMaxListeners() methods can be used to temporarily avoid this warning:

    import { EventEmitter } from 'node:events';
    const emitter = new EventEmitter();
    emitter.setMaxListeners(emitter.getMaxListeners() + 1);
    emitter.once('event', () => {
    // do stuff
    emitter.setMaxListeners(Math.max(emitter.getMaxListeners() - 1, 0));
    });

    The --trace-warnings command-line flag can be used to display the stack trace for such warnings.

    The emitted warning can be inspected with process.on('warning') and will have the additional emitter, type, and count properties, referring to the event emitter instance, the event's name and the number of attached listeners, respectively. Its name property is set to 'MaxListenersExceededWarning'.

    v0.11.2

    errorMonitor: typeof 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.

    v13.6.0, v12.17.0

    Methods

    • Type Parameters

      • K

      Parameters

      • error: Error
      • event: string | symbol
      • ...args: AnyRest

      Returns void

    • Alias for emitter.on(eventName, listener).

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol
      • listener: (...args: any[]) => void

      Returns this

      v0.1.26

    • 모든 클라이언트에게 메시지를 브로드캐스트합니다.

      Parameters

      • type: string

        메시지 타입

      • data: any

        전송할 데이터

      • excludeClientIds: string[] = []

        제외할 클라이언트 ID 목록

      Returns void

      this.broadcast('notice', { text: '서버 재시작' });
      
    • TCP 서버에 연결합니다.

      Parameters

      • host: string

        TCP 서버 호스트명

      • port: number

        TCP 서버 포트

      Returns void

      // TCP 서버에 연결
      this.connectToTcpServer('localhost', 9000);
      // 연결 후 pingPongInterval 설정
      this.pingPongInterval = setInterval(() => {
      this.sendToTcpServer('Hello TCP Server');
      }, 5000);
    • 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

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol
      • ...args: AnyRest

      Returns boolean

      v0.1.26

    • Returns an array listing the events for which the emitter has registered listeners. The values in the array are strings or Symbols.

      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) ]

      Returns (string | symbol)[]

      v6.0.0

    • 클라이언트 ID를 생성합니다.

      Returns string

      생성된 클라이언트 ID

      const id = this.generateClientId();
      
    • Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.

      Returns number

      v1.0.0

    • 클라이언트 연결 해제를 처리합니다.

      Parameters

      • clientId: string

        클라이언트 ID

      Returns void

      // 클라이언트 연결 해제 시
      this.handleClientDisconnect(clientId);
    • 클라이언트로부터의 메시지를 처리합니다.

      Parameters

      • clientId: string

        클라이언트 ID

      • data: any

        수신 데이터

      Returns void

      // 클라이언트 메시지 수신 시
      this.handleClientMessage(clientId, data);
    • 클라이언트 연결 파라미터를 처리합니다.

      Parameters

      • clientId: string

        클라이언트 ID

      • params: any

        파라미터 객체

      Returns void

      // Connection 메시지 타입 처리
      this.handleConnectionParams(clientId, params);
    • 클라이언트의 이벤트 구독을 처리합니다.

      Parameters

      • clientId: string

        클라이언트 ID

      • eventName: string

        구독할 이벤트명

      • Optionaldata: any

        추가 데이터(옵션)

      Returns string

      구독 ID

      // 클라이언트가 이벤트 구독 요청 시
      const subscriptionId = this.handleSubscription(clientId, 'RobotData');
    • 클라이언트의 이벤트 구독 해제를 처리합니다.

      Parameters

      • clientId: string

        클라이언트 ID

      • subscriptionId: string

        구독 ID

      Returns boolean

      성공 여부

      // 클라이언트가 구독 해제 요청 시
      const success = this.handleUnsubscription(clientId, subscriptionId);
    • 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.

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol

        The name of the event being listened for

      • Optionallistener: Function

        The event handler function

      Returns number

      v3.2.0

    • 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] ]

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol

      Returns Function[]

      v0.1.26

    • 이벤트 구독자에게 데이터를 전송합니다.

      Parameters

      • eventName: string

        이벤트명

      • data: any

        전송 데이터

      Returns void

      // 이벤트 구독자에게 데이터 전송
      this.notifyEventSubscribers('RobotData', { foo: 1 });
    • Alias for emitter.removeListener().

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol
      • listener: (...args: any[]) => void

      Returns this

      v10.0.0

    • 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

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol

        The name of the event.

      • listener: (...args: any[]) => void

        The callback function

      Returns this

      v0.1.101

    • 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

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol

        The name of the event.

      • listener: (...args: any[]) => void

        The callback function

      Returns this

      v0.3.0

    • 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.

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol

        The name of the event.

      • listener: (...args: any[]) => void

        The callback function

      Returns this

      v6.0.0

    • Adds a one-timelistener 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.

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol

        The name of the event.

      • listener: (...args: any[]) => void

        The callback function

      Returns this

      v6.0.0

    • 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');

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol

      Returns Function[]

      v9.4.0

    • 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.

      Parameters

      • OptionaleventName: string | symbol

      Returns this

      v0.1.26

    • 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 fromemit() 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 indices 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.

      Type Parameters

      • K

      Parameters

      • eventName: string | symbol
      • listener: (...args: any[]) => void

      Returns this

      v0.1.26

    • TCP 재연결을 예약합니다.

      Parameters

      • host: string

        TCP 서버 호스트명

      • port: number

        TCP 서버 포트

      Returns void

      // 재연결 시도 및 딜레이 적용
      this.scheduleTcpReconnect('localhost', 9000);
    • 클라이언트에게 메시지를 전송합니다.

      Parameters

      • clientId: string

        클라이언트의 고유 ID

      • type: string

        메시지 타입

      • data: any

        전송할 데이터

      Returns void

      this.sendToClient('client_1', 'message', { text: 'Hello' });
      
    • TCP 서버로 데이터를 전송합니다.

      Parameters

      • data: string | Buffer<ArrayBufferLike>

        전송할 데이터 (string 또는 Buffer)

      Returns boolean

      전송 성공 여부

      // TCP 서버로 데이터 전송
      this.sendToTcpServer('hello');
    • 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.

      Parameters

      • n: number

      Returns this

      v0.3.5

    • 기본 WebSocket 이벤트를 설정합니다.

      Returns void

      this.setupDefaultEvents();
      
    • WebSocket 연결 이벤트 및 클라이언트 등록을 처리합니다.

      Returns void

      // WebSocket 연결 시 클라이언트 등록 및 이벤트 바인딩
      this.wss.on('connection', (socket, request) => {
      const clientId = this.generateClientId();
      this.clients.set(clientId, { id: clientId, socket, lastActivity: Date.now(), subscriptions: new Map() });
      this.sendToClient(clientId, 'connection', { success: true, clientId });
      });
    • TCP 서버 연결을 초기화합니다.

      Parameters

      • host: string

        TCP 서버 호스트명

      • port: number

        TCP 서버 포트

      Returns void

      // TCP 서버 연결 초기화
      this.setupTcpClient('localhost', 9000);
    • 서버를 안전하게 종료합니다.

      Returns void

      this.shutdown();
      
    • 하트비트(heartbeat) 체크를 시작합니다.

      Returns void

      this.startHeartbeat();
      
    • TCP 데이터 브로드캐스트를 쓰로틀링하여 전송합니다.

      Parameters

      • eventName: string

        이벤트 이름

      • parsedData: any

        파싱된 데이터

      • receivedAt: number

        수신 시각 (timestamp)

      Returns void

      // TCP 데이터 수신 시 브로드캐스트
      this.throttledTcpBroadcast('RobotData', parsedData, receivedAt);
    • Listens once to the abort event on the provided signal.

      Listening to the abort event on abort signals is unsafe and may lead to resource leaks since another third party with the signal can call e.stopImmediatePropagation(). Unfortunately Node.js cannot change this since it would violate the web standard. Additionally, the original API makes it easy to forget to remove listeners.

      This API allows safely using AbortSignals in Node.js APIs by solving these two issues by listening to the event such that stopImmediatePropagation does not prevent the listener from running.

      Returns a disposable so that it may be unsubscribed from more easily.

      import { addAbortListener } from 'node:events';

      function example(signal) {
      let disposable;
      try {
      signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
      disposable = addAbortListener(signal, (e) => {
      // Do something when signal is aborted.
      });
      } finally {
      disposable?.[Symbol.dispose]();
      }
      }

      Parameters

      • signal: AbortSignal
      • resource: (event: Event) => void

      Returns Disposable

      Disposable that removes the abort listener.

      v20.5.0

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

      For EventEmitters this behaves exactly the same as calling .listeners on the emitter.

      For EventTargets this is the only way to get the event listeners for the event target. This is useful for debugging and diagnostic purposes.

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

      {
      const ee = new EventEmitter();
      const listener = () => console.log('Events are fun');
      ee.on('foo', listener);
      console.log(getEventListeners(ee, 'foo')); // [ [Function: listener] ]
      }
      {
      const et = new EventTarget();
      const listener = () => console.log('Events are fun');
      et.addEventListener('foo', listener);
      console.log(getEventListeners(et, 'foo')); // [ [Function: listener] ]
      }

      Parameters

      • emitter: EventEmitter<DefaultEventMap> | EventTarget
      • name: string | symbol

      Returns Function[]

      v15.2.0, v14.17.0

    • Returns the currently set max amount of listeners.

      For EventEmitters this behaves exactly the same as calling .getMaxListeners on the emitter.

      For EventTargets this is the only way to get the max event listeners for the event target. If the number of event handlers on a single EventTarget exceeds the max set, the EventTarget will print a warning.

      import { getMaxListeners, setMaxListeners, EventEmitter } from 'node:events';

      {
      const ee = new EventEmitter();
      console.log(getMaxListeners(ee)); // 10
      setMaxListeners(11, ee);
      console.log(getMaxListeners(ee)); // 11
      }
      {
      const et = new EventTarget();
      console.log(getMaxListeners(et)); // 10
      setMaxListeners(11, et);
      console.log(getMaxListeners(et)); // 11
      }

      Parameters

      • emitter: EventEmitter<DefaultEventMap> | EventTarget

      Returns number

      v19.9.0

    • A class method that returns the number of listeners for the given eventName registered on the given emitter.

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

      const myEmitter = new EventEmitter();
      myEmitter.on('event', () => {});
      myEmitter.on('event', () => {});
      console.log(listenerCount(myEmitter, 'event'));
      // Prints: 2

      Parameters

      • emitter: EventEmitter

        The emitter to query

      • eventName: string | symbol

        The event name

      Returns number

      v0.9.12

      Since v3.2.0 - Use listenerCount instead.

    • import { on, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ee = new EventEmitter();

      // Emit later on
      process.nextTick(() => {
      ee.emit('foo', 'bar');
      ee.emit('foo', 42);
      });

      for await (const event of on(ee, 'foo')) {
      // The execution of this inner block is synchronous and it
      // processes one event at a time (even with await). Do not use
      // if concurrent execution is required.
      console.log(event); // prints ['bar'] [42]
      }
      // Unreachable here

      Returns an AsyncIterator that iterates eventName events. It will throw if the EventEmitter emits 'error'. It removes all listeners when exiting the loop. The value returned by each iteration is an array composed of the emitted event arguments.

      An AbortSignal can be used to cancel waiting on events:

      import { on, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ac = new AbortController();

      (async () => {
      const ee = new EventEmitter();

      // Emit later on
      process.nextTick(() => {
      ee.emit('foo', 'bar');
      ee.emit('foo', 42);
      });

      for await (const event of on(ee, 'foo', { signal: ac.signal })) {
      // The execution of this inner block is synchronous and it
      // processes one event at a time (even with await). Do not use
      // if concurrent execution is required.
      console.log(event); // prints ['bar'] [42]
      }
      // Unreachable here
      })();

      process.nextTick(() => ac.abort());

      Use the close option to specify an array of event names that will end the iteration:

      import { on, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ee = new EventEmitter();

      // Emit later on
      process.nextTick(() => {
      ee.emit('foo', 'bar');
      ee.emit('foo', 42);
      ee.emit('close');
      });

      for await (const event of on(ee, 'foo', { close: ['close'] })) {
      console.log(event); // prints ['bar'] [42]
      }
      // the loop will exit after 'close' is emitted
      console.log('done'); // prints 'done'

      Parameters

      • emitter: EventEmitter
      • eventName: string | symbol
      • Optionaloptions: StaticEventEmitterIteratorOptions

      Returns AsyncIterator<any[]>

      An AsyncIterator that iterates eventName events emitted by the emitter

      v13.6.0, v12.16.0

    • import { on, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ee = new EventEmitter();

      // Emit later on
      process.nextTick(() => {
      ee.emit('foo', 'bar');
      ee.emit('foo', 42);
      });

      for await (const event of on(ee, 'foo')) {
      // The execution of this inner block is synchronous and it
      // processes one event at a time (even with await). Do not use
      // if concurrent execution is required.
      console.log(event); // prints ['bar'] [42]
      }
      // Unreachable here

      Returns an AsyncIterator that iterates eventName events. It will throw if the EventEmitter emits 'error'. It removes all listeners when exiting the loop. The value returned by each iteration is an array composed of the emitted event arguments.

      An AbortSignal can be used to cancel waiting on events:

      import { on, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ac = new AbortController();

      (async () => {
      const ee = new EventEmitter();

      // Emit later on
      process.nextTick(() => {
      ee.emit('foo', 'bar');
      ee.emit('foo', 42);
      });

      for await (const event of on(ee, 'foo', { signal: ac.signal })) {
      // The execution of this inner block is synchronous and it
      // processes one event at a time (even with await). Do not use
      // if concurrent execution is required.
      console.log(event); // prints ['bar'] [42]
      }
      // Unreachable here
      })();

      process.nextTick(() => ac.abort());

      Use the close option to specify an array of event names that will end the iteration:

      import { on, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ee = new EventEmitter();

      // Emit later on
      process.nextTick(() => {
      ee.emit('foo', 'bar');
      ee.emit('foo', 42);
      ee.emit('close');
      });

      for await (const event of on(ee, 'foo', { close: ['close'] })) {
      console.log(event); // prints ['bar'] [42]
      }
      // the loop will exit after 'close' is emitted
      console.log('done'); // prints 'done'

      Parameters

      • emitter: EventTarget
      • eventName: string
      • Optionaloptions: StaticEventEmitterIteratorOptions

      Returns AsyncIterator<any[]>

      An AsyncIterator that iterates eventName events emitted by the emitter

      v13.6.0, v12.16.0

    • Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.

      This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.

      import { once, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ee = new EventEmitter();

      process.nextTick(() => {
      ee.emit('myevent', 42);
      });

      const [value] = await once(ee, 'myevent');
      console.log(value);

      const err = new Error('kaboom');
      process.nextTick(() => {
      ee.emit('error', err);
      });

      try {
      await once(ee, 'myevent');
      } catch (err) {
      console.error('error happened', err);
      }

      The special handling of the 'error' event is only used when events.once() is used to wait for another event. If events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:

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

      const ee = new EventEmitter();

      once(ee, 'error')
      .then(([err]) => console.log('ok', err.message))
      .catch((err) => console.error('error', err.message));

      ee.emit('error', new Error('boom'));

      // Prints: ok boom

      An AbortSignal can be used to cancel waiting for the event:

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

      const ee = new EventEmitter();
      const ac = new AbortController();

      async function foo(emitter, event, signal) {
      try {
      await once(emitter, event, { signal });
      console.log('event emitted!');
      } catch (error) {
      if (error.name === 'AbortError') {
      console.error('Waiting for the event was canceled!');
      } else {
      console.error('There was an error', error.message);
      }
      }
      }

      foo(ee, 'foo', ac.signal);
      ac.abort(); // Abort waiting for the event
      ee.emit('foo'); // Prints: Waiting for the event was canceled!

      Parameters

      • emitter: EventEmitter
      • eventName: string | symbol
      • Optionaloptions: StaticEventEmitterOptions

      Returns Promise<any[]>

      v11.13.0, v10.16.0

    • Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.

      This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.

      import { once, EventEmitter } from 'node:events';
      import process from 'node:process';

      const ee = new EventEmitter();

      process.nextTick(() => {
      ee.emit('myevent', 42);
      });

      const [value] = await once(ee, 'myevent');
      console.log(value);

      const err = new Error('kaboom');
      process.nextTick(() => {
      ee.emit('error', err);
      });

      try {
      await once(ee, 'myevent');
      } catch (err) {
      console.error('error happened', err);
      }

      The special handling of the 'error' event is only used when events.once() is used to wait for another event. If events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:

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

      const ee = new EventEmitter();

      once(ee, 'error')
      .then(([err]) => console.log('ok', err.message))
      .catch((err) => console.error('error', err.message));

      ee.emit('error', new Error('boom'));

      // Prints: ok boom

      An AbortSignal can be used to cancel waiting for the event:

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

      const ee = new EventEmitter();
      const ac = new AbortController();

      async function foo(emitter, event, signal) {
      try {
      await once(emitter, event, { signal });
      console.log('event emitted!');
      } catch (error) {
      if (error.name === 'AbortError') {
      console.error('Waiting for the event was canceled!');
      } else {
      console.error('There was an error', error.message);
      }
      }
      }

      foo(ee, 'foo', ac.signal);
      ac.abort(); // Abort waiting for the event
      ee.emit('foo'); // Prints: Waiting for the event was canceled!

      Parameters

      • emitter: EventTarget
      • eventName: string
      • Optionaloptions: StaticEventEmitterOptions

      Returns Promise<any[]>

      v11.13.0, v10.16.0

    • import { setMaxListeners, EventEmitter } from 'node:events';

      const target = new EventTarget();
      const emitter = new EventEmitter();

      setMaxListeners(5, target, emitter);

      Parameters

      • Optionaln: number

        A non-negative number. The maximum number of listeners per EventTarget event.

      • ...eventTargets: (EventEmitter<DefaultEventMap> | EventTarget)[]

        Zero or more {EventTarget} or {EventEmitter} instances. If none are specified, n is set as the default max for all newly created {EventTarget} and {EventEmitter} objects.

      Returns void

      v15.4.0