Node dgram.Socket class | API Reference | Bun

Node dgram.Socket class | API Reference | BunBuildDocsReferenceGuidesBlogDiscord/node:dgram/SocketM[Symbol.asyncDispose]M[events.captureRejectionSymbol]MaddListenerMaddMembershipMaddressMaddSourceSpecificMembershipMbindMcloseMconnectCoconstructorMdisconnectMdropMembershipMdropSourceSpecificMembershipMemitMeventNamesMgetMaxListenersMgetRecvBufferSizeMgetSendBufferSizeMgetSendQueueCountMgetSendQueueSizeMlistenerCountMlistenersMoffMonMonceMprependListenerMprependOnceListenerMrawListenersMrefMremoteAddressMremoveAllListenersMremoveListenerMsendMsetBroadcastMsetMaxListenersMsetMulticastInterfaceMsetMulticastLoopbackMsetMulticastTTLMsetRecvBufferSizeMsetSendBufferSizeMsetTTLMunref

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BuildDocsReferenceGuidesBlogDiscord/node:dgram/SocketM[Symbol.asyncDispose]M[events.captureRejectionSymbol]MaddListenerMaddMembershipMaddressMaddSourceSpecificMembershipMbindMcloseMconnectCoconstructorMdisconnectMdropMembershipMdropSourceSpecificMembershipMemitMeventNamesMgetMaxListenersMgetRecvBufferSizeMgetSendBufferSizeMgetSendQueueCountMgetSendQueueSizeMlistenerCountMlistenersMoffMonMonceMprependListenerMprependOnceListenerMrawListenersMrefMremoteAddressMremoveAllListenersMremoveListenerMsendMsetBroadcastMsetMaxListenersMsetMulticastInterfaceMsetMulticastLoopbackMsetMulticastTTLMsetRecvBufferSizeMsetSendBufferSizeMsetTTLMunref

class

dgram.Socketclass SocketEncapsulates the datagram functionality.

New instances of dgram.Socket are created using createSocket. The new keyword is not to be used to create dgram.Socket instances.

[Symbol.asyncDispose](): Promisevoid>;Calls socket.close() and returns a promise that fulfills when the socket has closed.

[events.captureRejectionSymbol](error: Error,event: string | symbol,...args: any[]): void;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. } } addListenerE extends keyof SocketEventMap>(eventName: E,listener: (...args: SocketEventMap[E]) => void): this;Alias for emitter.on(eventName, listener).

addListener(eventName: string | symbol,listener: (...args: any[]) => void): this;Alias for emitter.on(eventName, listener).

{ s.addMembership('224.0.0.114'); }); } ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">addMembership(multicastAddress: string,multicastInterface?: string): void;Tells the kernel to join a multicast group at the given multicastAddress and multicastInterface using the IP_ADD_MEMBERSHIP socket option. If the multicastInterface argument is not specified, the operating system will choose one interface and will add membership to it. To add membership to every available interface, call addMembership multiple times, once per interface.

When called on an unbound socket, this method will implicitly bind to a random port, listening on all interfaces.

When sharing a UDP socket across multiple cluster workers, thesocket.addMembership() function must be called only once or anEADDRINUSE error will occur:

import cluster from 'node:cluster'; import dgram from 'node:dgram'; if (cluster.isPrimary) { cluster.fork(); // Works ok. cluster.fork(); // Fails with EADDRINUSE. } else { const s = dgram.createSocket('udp4'); s.bind(1234, () => { s.addMembership('224.0.0.114'); }); } address(): AddressInfo;Returns an object containing the address information for a socket. For UDP sockets, this object will contain address, family, and port properties.

This method throws EBADF if called on an unbound socket.

addSourceSpecificMembership(sourceAddress: string,groupAddress: string,multicastInterface?: string): void;Tells the kernel to join a source-specific multicast channel at the given sourceAddress and groupAddress, using the multicastInterface with the IP_ADD_SOURCE_MEMBERSHIP socket option. If the multicastInterface argument is not specified, the operating system will choose one interface and will add membership to it. To add membership to every available interface, call socket.addSourceSpecificMembership() multiple times, once per interface.

When called on an unbound socket, this method will implicitly bind to a random port, listening on all interfaces.

{ console.error(`server error:\n${err.stack}`); server.close(); }); server.on('message', (msg, rinfo) => { console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`); }); server.on('listening', () => { const address = server.address(); console.log(`server listening ${address.address}:${address.port}`); }); server.bind(41234); // Prints: server listening 0.0.0.0:41234 ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">bind(port?: number,address?: string,callback?: () => void): this;For UDP sockets, causes the dgram.Socket to listen for datagram messages on a named port and optional address. If port is not specified or is 0, the operating system will attempt to bind to a random port. If address is not specified, the operating system will attempt to listen on all addresses. Once binding is complete, a 'listening' event is emitted and the optional callback function is called.

Specifying both a 'listening' event listener and passing a callback to the socket.bind() method is not harmful but not very useful.

A bound datagram socket keeps the Node.js process running to receive datagram messages.

If binding fails, an 'error' event is generated. In rare case (e.g. attempting to bind with a closed socket), an Error may be thrown.

Example of a UDP server listening on port 41234:

import dgram from 'node:dgram'; const server = dgram.createSocket('udp4'); server.on('error', (err) => { console.error(`server error:\n${err.stack}`); server.close(); }); server.on('message', (msg, rinfo) => { console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`); }); server.on('listening', () => { const address = server.address(); console.log(`server listening ${address.address}:${address.port}`); }); server.bind(41234); // Prints: server listening 0.0.0.0:41234 @param callbackwith no parameters. Called when binding is complete.

bind(port?: number,callback?: () => void): this;For UDP sockets, causes the dgram.Socket to listen for datagram messages on a named port and optional address. If port is not specified or is 0, the operating system will attempt to bind to a random port. If address is not specified, the operating system will attempt to listen on all addresses. Once binding is complete, a 'listening' event is emitted and the optional callback function is called.

Specifying both a 'listening' event listener and passing a callback to the socket.bind() method is not harmful but not very useful.

A bound datagram socket keeps the Node.js process running to receive datagram messages.

If binding fails, an 'error' event is generated. In rare case (e.g. attempting to bind with a closed socket), an Error may be thrown.

Example of a UDP server listening on port 41234:

import dgram from 'node:dgram'; const server = dgram.createSocket('udp4'); server.on('error', (err) => { console.error(`server error:\n${err.stack}`); server.close(); }); server.on('message', (msg, rinfo) => { console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`); }); server.on('listening', () => { const address = server.address(); console.log(`server listening ${address.address}:${address.port}`); }); server.bind(41234); // Prints: server listening 0.0.0.0:41234 @param callbackwith no parameters. Called when binding is complete.

bind(callback?: () => void): this;For UDP sockets, causes the dgram.Socket to listen for datagram messages on a named port and optional address. If port is not specified or is 0, the operating system will attempt to bind to a random port. If address is not specified, the operating system will attempt to listen on all addresses. Once binding is complete, a 'listening' event is emitted and the optional callback function is called.

Specifying both a 'listening' event listener and passing a callback to the socket.bind() method is not harmful but not very useful.

A bound datagram socket keeps the Node.js process running to receive datagram messages.

If binding fails, an 'error' event is generated. In rare case (e.g. attempting to bind with a closed socket), an Error may be thrown.

Example of a UDP server listening on port 41234:

import dgram from 'node:dgram'; const server = dgram.createSocket('udp4'); server.on('error', (err) => { console.error(`server error:\n${err.stack}`); server.close(); }); server.on('message', (msg, rinfo) => { console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`); }); server.on('listening', () => { const address = server.address(); console.log(`server listening ${address.address}:${address.port}`); }); server.bind(41234); // Prints: server listening 0.0.0.0:41234 @param callbackwith no parameters. Called when binding is complete.

bind(options: BindOptions,callback?: () => void): this;For UDP sockets, causes the dgram.Socket to listen for datagram messages on a named port and optional address. If port is not specified or is 0, the operating system will attempt to bind to a random port. If address is not specified, the operating system will attempt to listen on all addresses. Once binding is complete, a 'listening' event is emitted and the optional callback function is called.

Specifying both a 'listening' event listener and passing a callback to the socket.bind() method is not harmful but not very useful.

A bound datagram socket keeps the Node.js process running to receive datagram messages.

If binding fails, an 'error' event is generated. In rare case (e.g. attempting to bind with a closed socket), an Error may be thrown.

Example of a UDP server listening on port 41234:

import dgram from 'node:dgram'; const server = dgram.createSocket('udp4'); server.on('error', (err) => { console.error(`server error:\n${err.stack}`); server.close(); }); server.on('message', (msg, rinfo) => { console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`); }); server.on('listening', () => { const address = server.address(); console.log(`server listening ${address.address}:${address.port}`); }); server.bind(41234); // Prints: server listening 0.0.0.0:41234 @param callbackwith no parameters. Called when binding is complete.

close(callback?: () => void): this;Close the underlying socket and stop listening for data on it. If a callback is provided, it is added as a listener for the 'close' event.

@param callbackCalled when the socket has been closed.

connect(port: number,address?: string,callback?: () => void): void;Associates the dgram.Socket to a remote address and port. Every message sent by this handle is automatically sent to that destination. Also, the socket will only receive messages from that remote peer. Trying to call connect() on an already connected socket will result in an ERR_SOCKET_DGRAM_IS_CONNECTED exception. If address is not provided, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default. Once the connection is complete, a 'connect' event is emitted and the optional callback function is called. In case of failure, the callback is called or, failing this, an 'error' event is emitted.

@param callbackCalled when the connection is completed or on error.

connect(port: number,callback: () => void): void;Associates the dgram.Socket to a remote address and port. Every message sent by this handle is automatically sent to that destination. Also, the socket will only receive messages from that remote peer. Trying to call connect() on an already connected socket will result in an ERR_SOCKET_DGRAM_IS_CONNECTED exception. If address is not provided, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default. Once the connection is complete, a 'connect' event is emitted and the optional callback function is called. In case of failure, the callback is called or, failing this, an 'error' event is emitted.

@param callbackCalled when the connection is completed or on error.

disconnect(): void;A synchronous function that disassociates a connected dgram.Socket from its remote address. Trying to call disconnect() on an unbound or already disconnected socket will result in an ERR_SOCKET_DGRAM_NOT_CONNECTED exception.

dropMembership(multicastAddress: string,multicastInterface?: string): void;Instructs the kernel to leave a multicast group at multicastAddress using the IP_DROP_MEMBERSHIP socket option. This method is automatically called by the kernel when the socket is closed or the process terminates, so most apps will never have reason to call this.

If multicastInterface is not specified, the operating system will attempt to drop membership on all valid interfaces.

dropSourceSpecificMembership(sourceAddress: string,groupAddress: string,multicastInterface?: string): void;Instructs the kernel to leave a source-specific multicast channel at the given sourceAddress and groupAddress using the IP_DROP_SOURCE_MEMBERSHIP socket option. This method is automatically called by the kernel when the socket is closed or the process terminates, so most apps will never have reason to call this.

If multicastInterface is not specified, the operating system will attempt to drop membership on all valid interfaces.

emitE extends keyof SocketEventMap>(eventName: E,...args: SocketEventMap[E]): boolean;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 emit(eventName: string | symbol,...args: any[]): boolean;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 {}); myEE.on('bar', () => {}); const sym = Symbol('symbol'); myEE.on(sym, () => {}); console.log(myEE.eventNames()); // Prints: [ 'foo', 'bar', Symbol(symbol) ] ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">eventNames(): string | symbol[];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(): number;Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to events.defaultMaxListeners.

getRecvBufferSize(): number;This method throws ERR_SOCKET_BUFFER_SIZE if called on an unbound socket.

@returnsthe SO_RCVBUF socket receive buffer size in bytes.

getSendBufferSize(): number;This method throws ERR_SOCKET_BUFFER_SIZE if called on an unbound socket.

@returnsthe SO_SNDBUF socket send buffer size in bytes.

getSendQueueCount(): number;@returnsNumber of send requests currently in the queue awaiting to be processed.

getSendQueueSize(): number;@returnsNumber of bytes queued for sending.

listenerCountE extends keyof SocketEventMap>(eventName: E,listener?: (...args: SocketEventMap[E]) => void): number;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.

@param eventNameThe name of the event being listened for

@param listenerThe event handler function

listenerCount(eventName: string | symbol,listener?: (...args: any[]) => void): number;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.

@param eventNameThe name of the event being listened for

@param listenerThe event handler function

{ console.log('someone connected!'); }); console.log(util.inspect(server.listeners('connection'))); // Prints: [ [Function] ] ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">listenersE extends keyof SocketEventMap>(eventName: E): (...args: SocketEventMap[E]) => void[];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] ] listeners(eventName: string | symbol): (...args: any[]) => void[];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] ] offE extends keyof SocketEventMap>(eventName: E,listener: (...args: SocketEventMap[E]) => void): this;Alias for emitter.removeListener().

off(eventName: string | symbol,listener: (...args: any[]) => void): this;Alias for emitter.removeListener().

{ 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. ```js 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 ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">onE extends keyof SocketEventMap>(eventName: E,listener: (...args: SocketEventMap[E]) => void): this;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 @param eventNameThe name of the event.

@param listenerThe callback function

on(eventName: string | symbol,listener: (...args: any[]) => void): this;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 @param eventNameThe name of the event.

@param listenerThe callback function

{ 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. ```js 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 ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">onceE extends keyof SocketEventMap>(eventName: E,listener: (...args: SocketEventMap[E]) => void): this;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 @param eventNameThe name of the event.

@param listenerThe callback function

once(eventName: string | symbol,listener: (...args: any[]) => void): this;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 @param eventNameThe name of the event.

@param listenerThe callback function

{ console.log('someone connected!'); }); ``` Returns a reference to the `EventEmitter`, so that calls can be chained." data-algolia-static="false" data-algolia-merged="false" data-type="Method">prependListenerE extends keyof SocketEventMap>(eventName: E,listener: (...args: SocketEventMap[E]) => void): this;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.

@param eventNameThe name of the event.

@param listenerThe callback function

prependListener(eventName: string | symbol,listener: (...args: any[]) => void): this;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.

@param eventNameThe name of the event.

@param listenerThe callback function

{ console.log('Ah, we have our first user!'); }); ``` Returns a reference to the `EventEmitter`, so that calls can be chained." data-algolia-static="false" data-algolia-merged="false" data-type="Method">prependOnceListenerE extends keyof SocketEventMap>(eventName: E,listener: (...args: SocketEventMap[E]) => void): this;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.

@param eventNameThe name of the event.

@param listenerThe callback function

prependOnceListener(eventName: string | symbol,listener: (...args: any[]) => void): this;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.

@param eventNameThe name of the event.

@param listenerThe callback function

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'); ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">rawListenersE extends keyof SocketEventMap>(eventName: E): (...args: SocketEventMap[E]) => void[];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'); rawListeners(eventName: string | symbol): (...args: any[]) => void[];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'); ref(): this;By default, binding a socket will cause it to block the Node.js process from exiting as long as the socket is open. The socket.unref() method can be used to exclude the socket from the reference counting that keeps the Node.js process active. The socket.ref() method adds the socket back to the reference counting and restores the default behavior.

Calling socket.ref() multiples times will have no additional effect.

The socket.ref() method returns a reference to the socket so calls can be chained.

remoteAddress(): AddressInfo;Returns an object containing the address, family, and port of the remote endpoint. This method throws an ERR_SOCKET_DGRAM_NOT_CONNECTED exception if the socket is not connected.

removeAllListenersE extends keyof SocketEventMap>(eventName?: E): this;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.

removeAllListeners(eventName?: string | symbol): this;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.

{ 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. ```js 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: ```js 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." data-algolia-static="false" data-algolia-merged="false" data-type="Method">removeListenerE extends keyof SocketEventMap>(eventName: E,listener: (...args: SocketEventMap[E]) => void): this;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.

removeListener(eventName: string | symbol,listener: (...args: any[]) => void): this;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.

{ client.close(); }); ``` Example of sending a UDP packet composed of multiple buffers to a port on`127.0.0.1`; ```js import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const buf1 = Buffer.from('Some '); const buf2 = Buffer.from('bytes'); const client = dgram.createSocket('udp4'); client.send([buf1, buf2], 41234, (err) => { client.close(); }); ``` Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster. Example of sending a UDP packet using a socket connected to a port on `localhost`: ```js import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">send(msg: string | readonly any[] | ArrayBufferViewArrayBufferLike>,port?: number,address?: string,callback?: (error: null | Error, bytes: number) => void): void;Broadcasts a datagram on the socket. For connectionless sockets, the destination port and address must be specified. Connected sockets, on the other hand, will use their associated remote endpoint, so the port and address arguments must not be set.

The msg argument contains the message to be sent. Depending on its type, different behavior can apply. If msg is a Buffer, any TypedArray or a DataView, the offset and length specify the offset within the Buffer where the message begins and the number of bytes in the message, respectively. If msg is a String, then it is automatically converted to a Buffer with 'utf8' encoding. With messages that contain multi-byte characters, offset and length will be calculated with respect to byte length and not the character position. If msg is an array, offset and length must not be specified.

The address argument is a string. If the value of address is a host name, DNS will be used to resolve the address of the host. If address is not provided or otherwise nullish, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default.

If the socket has not been previously bound with a call to bind, the socket is assigned a random port number and is bound to the "all interfaces" address ('0.0.0.0' for udp4 sockets, '::0' for udp6 sockets.)

An optional callback function may be specified to as a way of reporting DNS errors or for determining when it is safe to reuse the buf object. DNS lookups delay the time to send for at least one tick of the Node.js event loop.

The only way to know for sure that the datagram has been sent is by using a callback. If an error occurs and a callback is given, the error will be passed as the first argument to the callback. If a callback is not given, the error is emitted as an 'error' event on the socket object.

Offset and length are optional but both must be set if either are used. They are supported only when the first argument is a Buffer, a TypedArray, or a DataView.

This method throws ERR_SOCKET_BAD_PORT if called on an unbound socket.

Example of sending a UDP packet to a port on localhost;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.send(message, 41234, 'localhost', (err) => { client.close(); }); Example of sending a UDP packet composed of multiple buffers to a port on127.0.0.1;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const buf1 = Buffer.from('Some '); const buf2 = Buffer.from('bytes'); const client = dgram.createSocket('udp4'); client.send([buf1, buf2], 41234, (err) => { client.close(); }); Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster.

Example of sending a UDP packet using a socket connected to a port on localhost:

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); @param msgMessage to be sent.

@param portDestination port.

@param addressDestination host name or IP address.

@param callbackCalled when the message has been sent.

send(msg: string | readonly any[] | ArrayBufferViewArrayBufferLike>,port?: number,callback?: (error: null | Error, bytes: number) => void): void;Broadcasts a datagram on the socket. For connectionless sockets, the destination port and address must be specified. Connected sockets, on the other hand, will use their associated remote endpoint, so the port and address arguments must not be set.

The msg argument contains the message to be sent. Depending on its type, different behavior can apply. If msg is a Buffer, any TypedArray or a DataView, the offset and length specify the offset within the Buffer where the message begins and the number of bytes in the message, respectively. If msg is a String, then it is automatically converted to a Buffer with 'utf8' encoding. With messages that contain multi-byte characters, offset and length will be calculated with respect to byte length and not the character position. If msg is an array, offset and length must not be specified.

The address argument is a string. If the value of address is a host name, DNS will be used to resolve the address of the host. If address is not provided or otherwise nullish, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default.

If the socket has not been previously bound with a call to bind, the socket is assigned a random port number and is bound to the "all interfaces" address ('0.0.0.0' for udp4 sockets, '::0' for udp6 sockets.)

An optional callback function may be specified to as a way of reporting DNS errors or for determining when it is safe to reuse the buf object. DNS lookups delay the time to send for at least one tick of the Node.js event loop.

The only way to know for sure that the datagram has been sent is by using a callback. If an error occurs and a callback is given, the error will be passed as the first argument to the callback. If a callback is not given, the error is emitted as an 'error' event on the socket object.

Offset and length are optional but both must be set if either are used. They are supported only when the first argument is a Buffer, a TypedArray, or a DataView.

This method throws ERR_SOCKET_BAD_PORT if called on an unbound socket.

Example of sending a UDP packet to a port on localhost;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.send(message, 41234, 'localhost', (err) => { client.close(); }); Example of sending a UDP packet composed of multiple buffers to a port on127.0.0.1;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const buf1 = Buffer.from('Some '); const buf2 = Buffer.from('bytes'); const client = dgram.createSocket('udp4'); client.send([buf1, buf2], 41234, (err) => { client.close(); }); Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster.

Example of sending a UDP packet using a socket connected to a port on localhost:

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); @param msgMessage to be sent.

@param portDestination port.

@param callbackCalled when the message has been sent.

send(msg: string | readonly any[] | ArrayBufferViewArrayBufferLike>,callback?: (error: null | Error, bytes: number) => void): void;Broadcasts a datagram on the socket. For connectionless sockets, the destination port and address must be specified. Connected sockets, on the other hand, will use their associated remote endpoint, so the port and address arguments must not be set.

The msg argument contains the message to be sent. Depending on its type, different behavior can apply. If msg is a Buffer, any TypedArray or a DataView, the offset and length specify the offset within the Buffer where the message begins and the number of bytes in the message, respectively. If msg is a String, then it is automatically converted to a Buffer with 'utf8' encoding. With messages that contain multi-byte characters, offset and length will be calculated with respect to byte length and not the character position. If msg is an array, offset and length must not be specified.

The address argument is a string. If the value of address is a host name, DNS will be used to resolve the address of the host. If address is not provided or otherwise nullish, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default.

If the socket has not been previously bound with a call to bind, the socket is assigned a random port number and is bound to the "all interfaces" address ('0.0.0.0' for udp4 sockets, '::0' for udp6 sockets.)

An optional callback function may be specified to as a way of reporting DNS errors or for determining when it is safe to reuse the buf object. DNS lookups delay the time to send for at least one tick of the Node.js event loop.

The only way to know for sure that the datagram has been sent is by using a callback. If an error occurs and a callback is given, the error will be passed as the first argument to the callback. If a callback is not given, the error is emitted as an 'error' event on the socket object.

Offset and length are optional but both must be set if either are used. They are supported only when the first argument is a Buffer, a TypedArray, or a DataView.

This method throws ERR_SOCKET_BAD_PORT if called on an unbound socket.

Example of sending a UDP packet to a port on localhost;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.send(message, 41234, 'localhost', (err) => { client.close(); }); Example of sending a UDP packet composed of multiple buffers to a port on127.0.0.1;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const buf1 = Buffer.from('Some '); const buf2 = Buffer.from('bytes'); const client = dgram.createSocket('udp4'); client.send([buf1, buf2], 41234, (err) => { client.close(); }); Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster.

Example of sending a UDP packet using a socket connected to a port on localhost:

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); @param msgMessage to be sent.

@param callbackCalled when the message has been sent.

send(msg: string | ArrayBufferViewArrayBufferLike>,offset: number,length: number,port?: number,address?: string,callback?: (error: null | Error, bytes: number) => void): void;Broadcasts a datagram on the socket. For connectionless sockets, the destination port and address must be specified. Connected sockets, on the other hand, will use their associated remote endpoint, so the port and address arguments must not be set.

The msg argument contains the message to be sent. Depending on its type, different behavior can apply. If msg is a Buffer, any TypedArray or a DataView, the offset and length specify the offset within the Buffer where the message begins and the number of bytes in the message, respectively. If msg is a String, then it is automatically converted to a Buffer with 'utf8' encoding. With messages that contain multi-byte characters, offset and length will be calculated with respect to byte length and not the character position. If msg is an array, offset and length must not be specified.

The address argument is a string. If the value of address is a host name, DNS will be used to resolve the address of the host. If address is not provided or otherwise nullish, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default.

If the socket has not been previously bound with a call to bind, the socket is assigned a random port number and is bound to the "all interfaces" address ('0.0.0.0' for udp4 sockets, '::0' for udp6 sockets.)

An optional callback function may be specified to as a way of reporting DNS errors or for determining when it is safe to reuse the buf object. DNS lookups delay the time to send for at least one tick of the Node.js event loop.

The only way to know for sure that the datagram has been sent is by using a callback. If an error occurs and a callback is given, the error will be passed as the first argument to the callback. If a callback is not given, the error is emitted as an 'error' event on the socket object.

Offset and length are optional but both must be set if either are used. They are supported only when the first argument is a Buffer, a TypedArray, or a DataView.

This method throws ERR_SOCKET_BAD_PORT if called on an unbound socket.

Example of sending a UDP packet to a port on localhost;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.send(message, 41234, 'localhost', (err) => { client.close(); }); Example of sending a UDP packet composed of multiple buffers to a port on127.0.0.1;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const buf1 = Buffer.from('Some '); const buf2 = Buffer.from('bytes'); const client = dgram.createSocket('udp4'); client.send([buf1, buf2], 41234, (err) => { client.close(); }); Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster.

Example of sending a UDP packet using a socket connected to a port on localhost:

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); @param msgMessage to be sent.

@param offsetOffset in the buffer where the message starts.

@param lengthNumber of bytes in the message.

@param portDestination port.

@param addressDestination host name or IP address.

@param callbackCalled when the message has been sent.

send(msg: string | ArrayBufferViewArrayBufferLike>,offset: number,length: number,port?: number,callback?: (error: null | Error, bytes: number) => void): void;Broadcasts a datagram on the socket. For connectionless sockets, the destination port and address must be specified. Connected sockets, on the other hand, will use their associated remote endpoint, so the port and address arguments must not be set.

The msg argument contains the message to be sent. Depending on its type, different behavior can apply. If msg is a Buffer, any TypedArray or a DataView, the offset and length specify the offset within the Buffer where the message begins and the number of bytes in the message, respectively. If msg is a String, then it is automatically converted to a Buffer with 'utf8' encoding. With messages that contain multi-byte characters, offset and length will be calculated with respect to byte length and not the character position. If msg is an array, offset and length must not be specified.

The address argument is a string. If the value of address is a host name, DNS will be used to resolve the address of the host. If address is not provided or otherwise nullish, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default.

If the socket has not been previously bound with a call to bind, the socket is assigned a random port number and is bound to the "all interfaces" address ('0.0.0.0' for udp4 sockets, '::0' for udp6 sockets.)

An optional callback function may be specified to as a way of reporting DNS errors or for determining when it is safe to reuse the buf object. DNS lookups delay the time to send for at least one tick of the Node.js event loop.

The only way to know for sure that the datagram has been sent is by using a callback. If an error occurs and a callback is given, the error will be passed as the first argument to the callback. If a callback is not given, the error is emitted as an 'error' event on the socket object.

Offset and length are optional but both must be set if either are used. They are supported only when the first argument is a Buffer, a TypedArray, or a DataView.

This method throws ERR_SOCKET_BAD_PORT if called on an unbound socket.

Example of sending a UDP packet to a port on localhost;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.send(message, 41234, 'localhost', (err) => { client.close(); }); Example of sending a UDP packet composed of multiple buffers to a port on127.0.0.1;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const buf1 = Buffer.from('Some '); const buf2 = Buffer.from('bytes'); const client = dgram.createSocket('udp4'); client.send([buf1, buf2], 41234, (err) => { client.close(); }); Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster.

Example of sending a UDP packet using a socket connected to a port on localhost:

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); @param msgMessage to be sent.

@param offsetOffset in the buffer where the message starts.

@param lengthNumber of bytes in the message.

@param portDestination port.

@param callbackCalled when the message has been sent.

send(msg: string | ArrayBufferViewArrayBufferLike>,offset: number,length: number,callback?: (error: null | Error, bytes: number) => void): void;Broadcasts a datagram on the socket. For connectionless sockets, the destination port and address must be specified. Connected sockets, on the other hand, will use their associated remote endpoint, so the port and address arguments must not be set.

The msg argument contains the message to be sent. Depending on its type, different behavior can apply. If msg is a Buffer, any TypedArray or a DataView, the offset and length specify the offset within the Buffer where the message begins and the number of bytes in the message, respectively. If msg is a String, then it is automatically converted to a Buffer with 'utf8' encoding. With messages that contain multi-byte characters, offset and length will be calculated with respect to byte length and not the character position. If msg is an array, offset and length must not be specified.

The address argument is a string. If the value of address is a host name, DNS will be used to resolve the address of the host. If address is not provided or otherwise nullish, '127.0.0.1' (for udp4 sockets) or '::1' (for udp6 sockets) will be used by default.

If the socket has not been previously bound with a call to bind, the socket is assigned a random port number and is bound to the "all interfaces" address ('0.0.0.0' for udp4 sockets, '::0' for udp6 sockets.)

An optional callback function may be specified to as a way of reporting DNS errors or for determining when it is safe to reuse the buf object. DNS lookups delay the time to send for at least one tick of the Node.js event loop.

The only way to know for sure that the datagram has been sent is by using a callback. If an error occurs and a callback is given, the error will be passed as the first argument to the callback. If a callback is not given, the error is emitted as an 'error' event on the socket object.

Offset and length are optional but both must be set if either are used. They are supported only when the first argument is a Buffer, a TypedArray, or a DataView.

This method throws ERR_SOCKET_BAD_PORT if called on an unbound socket.

Example of sending a UDP packet to a port on localhost;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.send(message, 41234, 'localhost', (err) => { client.close(); }); Example of sending a UDP packet composed of multiple buffers to a port on127.0.0.1;

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const buf1 = Buffer.from('Some '); const buf2 = Buffer.from('bytes'); const client = dgram.createSocket('udp4'); client.send([buf1, buf2], 41234, (err) => { client.close(); }); Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster.

Example of sending a UDP packet using a socket connected to a port on localhost:

import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); @param msgMessage to be sent.

@param offsetOffset in the buffer where the message starts.

@param lengthNumber of bytes in the message.

@param callbackCalled when the message has been sent.

setBroadcast(flag: boolean): void;Sets or clears the SO_BROADCAST socket option. When set to true, UDP packets may be sent to a local interface's broadcast address.

This method throws EBADF if called on an unbound socket.

setMaxListeners(n: number): this;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.

{ socket.setMulticastInterface('::%eth1'); }); ``` On Windows, where scope format uses an interface number: ```js const socket = dgram.createSocket('udp6'); socket.bind(1234, () => { socket.setMulticastInterface('::%2'); }); ``` #### Example: IPv4 outgoing multicast interface All systems use an IP of the host on the desired physical interface: ```js const socket = dgram.createSocket('udp4'); socket.bind(1234, () => { socket.setMulticastInterface('10.0.0.2'); }); ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">setMulticastInterface(multicastInterface: string): void;All references to scope in this section are referring to IPv6 Zone Indices, which are defined by RFC 4007. In string form, an IP with a scope index is written as 'IP%scope' where scope is an interface name or interface number.

Sets the default outgoing multicast interface of the socket to a chosen interface or back to system interface selection. The multicastInterface must be a valid string representation of an IP from the socket's family.

For IPv4 sockets, this should be the IP configured for the desired physical interface. All packets sent to multicast on the socket will be sent on the interface determined by the most recent successful use of this call.

For IPv6 sockets, multicastInterface should include a scope to indicate the interface as in the examples that follow. In IPv6, individual send calls can also use explicit scope in addresses, so only packets sent to a multicast address without specifying an explicit scope are affected by the most recent successful use of this call.

This method throws EBADF if called on an unbound socket.

Example: IPv6 outgoing multicast interfaceOn most systems, where scope format uses the interface name:

const socket = dgram.createSocket('udp6'); socket.bind(1234, () => { socket.setMulticastInterface('::%eth1'); }); On Windows, where scope format uses an interface number:

const socket = dgram.createSocket('udp6'); socket.bind(1234, () => { socket.setMulticastInterface('::%2'); }); Example: IPv4 outgoing multicast interfaceAll systems use an IP of the host on the desired physical interface:

const socket = dgram.createSocket('udp4'); socket.bind(1234, () => { socket.setMulticastInterface('10.0.0.2'); }); setMulticastLoopback(flag: boolean): boolean;Sets or clears the IP_MULTICAST_LOOP socket option. When set to true, multicast packets will also be received on the local interface.

This method throws EBADF if called on an unbound socket.

setMulticastTTL(ttl: number): number;Sets the IP_MULTICAST_TTL socket option. While TTL generally stands for "Time to Live", in this context it specifies the number of IP hops that a packet is allowed to travel through, specifically for multicast traffic. Each router or gateway that forwards a packet decrements the TTL. If the TTL is decremented to 0 by a router, it will not be forwarded.

The ttl argument may be between 0 and 255. The default on most systems is 1.

This method throws EBADF if called on an unbound socket.

setRecvBufferSize(size: number): void;Sets the SO_RCVBUF socket option. Sets the maximum socket receive buffer in bytes.

This method throws ERR_SOCKET_BUFFER_SIZE if called on an unbound socket.

setSendBufferSize(size: number): void;Sets the SO_SNDBUF socket option. Sets the maximum socket send buffer in bytes.

This method throws ERR_SOCKET_BUFFER_SIZE if called on an unbound socket.

setTTL(ttl: number): number;Sets the IP_TTL socket option. While TTL generally stands for "Time to Live", in this context it specifies the number of IP hops that a packet is allowed to travel through. Each router or gateway that forwards a packet decrements the TTL. If the TTL is decremented to 0 by a router, it will not be forwarded. Changing TTL values is typically done for network probes or when multicasting.

The ttl argument may be between 1 and 255. The default on most systems is 64.

This method throws EBADF if called on an unbound socket.

unref(): this;By default, binding a socket will cause it to block the Node.js process from exiting as long as the socket is open. The socket.unref() method can be used to exclude the socket from the reference counting that keeps the Node.js process active, allowing the process to exit even if the socket is still listening.

Calling socket.unref() multiple times will have no additional effect.

The socket.unref() method returns a reference to the socket so calls can be chained.

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