Identifying paths for IPC connections#

net.connect(),net.createConnection(),server.listen(), andsocket.connect() take apath parameter to identify IPC endpoints.

On Unix, the local domain is also known as the Unix domain. The path is afile system pathname. It will throw an error when the length of pathname isgreater than the length ofsizeof(sockaddr_un.sun_path). Typical values are107 bytes on Linux and 103 bytes on macOS. If a Node.js API abstraction createsthe Unix domain socket, it will unlink the Unix domain socket as well. Forexample,net.createServer() may create a Unix domain socket andserver.close() will unlink it. But if a user creates the Unix domainsocket outside of these abstractions, the user will need to remove it. The sameapplies when a Node.js API creates a Unix domain socket but the program thencrashes. In short, a Unix domain socket will be visible in the file system andwill persist until unlinked. On Linux, You can use Unix abstract socket by adding\0 to the beginning of the path, such as\0abstract. The path to the Unixabstract socket is not visible in the file system and it will disappear automaticallywhen all open references to the socket are closed.

On Windows, the local domain is implemented using a named pipe. The pathmustrefer to an entry in\\?\pipe\ or\\.\pipe\. Any characters are permitted,but the latter may do some processing of pipe names, such as resolving..sequences. Despite how it might look, the pipe namespace is flat. Pipes willnot persist. They are removed when the last reference to them is closed.Unlike Unix domain sockets, Windows will close and remove the pipe when theowning process exits.

JavaScript string escaping requires paths to be specified with extra backslashescaping such as:

net.createServer().listen(  path.join('\\\\?\\pipe', process.cwd(),'myctl'));copy

blockList.addAddress(address[, type])#

• address<string> |<net.SocketAddress> An IPv4 or IPv6 address.
• type<string> Either'ipv4' or'ipv6'.Default:'ipv4'.

Adds a rule to block the given IP address.

blockList.addRange(start, end[, type])#

• start<string> |<net.SocketAddress> The starting IPv4 or IPv6 address in therange.
• end<string> |<net.SocketAddress> The ending IPv4 or IPv6 address in the range.
• type<string> Either'ipv4' or'ipv6'.Default:'ipv4'.

Adds a rule to block a range of IP addresses fromstart (inclusive) toend (inclusive).

blockList.addSubnet(net, prefix[, type])#

• net<string> |<net.SocketAddress> The network IPv4 or IPv6 address.
• prefix<number> The number of CIDR prefix bits. For IPv4, thismust be a value between0 and32. For IPv6, this must be between0 and128.
• type<string> Either'ipv4' or'ipv6'.Default:'ipv4'.

Adds a rule to block a range of IP addresses specified as a subnet mask.

blockList.check(address[, type])#

• address<string> |<net.SocketAddress> The IP address to check
• type<string> Either'ipv4' or'ipv6'.Default:'ipv4'.
• Returns:<boolean>

Returnstrue if the given IP address matches any of the rules added to theBlockList.

const blockList =new net.BlockList();blockList.addAddress('123.123.123.123');blockList.addRange('10.0.0.1','10.0.0.10');blockList.addSubnet('8592:757c:efae:4e45::',64,'ipv6');console.log(blockList.check('123.123.123.123'));// Prints: trueconsole.log(blockList.check('10.0.0.3'));// Prints: trueconsole.log(blockList.check('222.111.111.222'));// Prints: false// IPv6 notation for IPv4 addresses works:console.log(blockList.check('::ffff:7b7b:7b7b','ipv6'));// Prints: trueconsole.log(blockList.check('::ffff:123.123.123.123','ipv6'));// Prints: truecopy

blockList.rules#

• Type:<string[]>

The list of rules added to the blocklist.

BlockList.isBlockList(value)#

• value<any> Any JS value
• Returnstrue if thevalue is anet.BlockList.

blockList.fromJSON(value)#

const blockList =new net.BlockList();const data = ['Subnet: IPv4 192.168.1.0/24','Address: IPv4 10.0.0.5','Range: IPv4 192.168.2.1-192.168.2.10','Range: IPv4 10.0.0.1-10.0.0.10',];blockList.fromJSON(data);blockList.fromJSON(JSON.stringify(data));copy

• value Blocklist.rules

blockList.toJSON()#

• Returns Blocklist.rules

new net.SocketAddress([options])#

• options<Object>
  • address<string> The network address as either an IPv4 or IPv6 string.Default:'127.0.0.1' iffamily is'ipv4';'::' iffamily is'ipv6'.
  • family<string> One of either'ipv4' or'ipv6'.Default:'ipv4'.
  • flowlabel<number> An IPv6 flow-label used only iffamily is'ipv6'.
  • port<number> An IP port.

socketaddress.address#

• Type:<string>

socketaddress.family#

• Type:<string> Either'ipv4' or'ipv6'.

socketaddress.flowlabel#

• Type:<number>

socketaddress.port#

• Type:<number>

SocketAddress.parse(input)#

• input<string> An input string containing an IP address and optional port,e.g.123.1.2.3:1234 or[1::1]:1234.
• Returns:<net.SocketAddress> Returns aSocketAddress if parsing was successful.Otherwise returnsundefined.

new net.Server([options][, connectionListener])#

• options<Object> Seenet.createServer([options][, connectionListener]).
• connectionListener<Function> Automatically set as a listener for the'connection' event.
• Returns:<net.Server>

net.Server is anEventEmitter with the following events:

Event:'close'#

Emitted when the server closes. If connections exist, thisevent is not emitted until all connections are ended.

Event:'connection'#

• Type:<net.Socket> The connection object

Emitted when a new connection is made.socket is an instance ofnet.Socket.

Event:'error'#

• Type:<Error>

Emitted when an error occurs. Unlikenet.Socket, the'close'event willnot be emitted directly following this event unlessserver.close() is manually called. See the example in discussion ofserver.listen().

Event:'listening'#

Emitted when the server has been bound after callingserver.listen().

Event:'drop'#

When the number of connections reaches the threshold ofserver.maxConnections,the server will drop new connections and emit'drop' event instead. If it is aTCP server, the argument is as follows, otherwise the argument isundefined.

• data<Object> The argument passed to event listener.
  • localAddress<string> Local address.
  • localPort<number> Local port.
  • localFamily<string> Local family.
  • remoteAddress<string> Remote address.
  • remotePort<number> Remote port.
  • remoteFamily<string> Remote IP family.'IPv4' or'IPv6'.

server.address()#

• Returns:<Object> |<string> |<null>

Returns the boundaddress, the addressfamily name, andport of the serveras reported by the operating system if listening on an IP socket(useful to find which port was assigned when getting an OS-assigned address):{ port: 12346, family: 'IPv4', address: '127.0.0.1' }.

For a server listening on a pipe or Unix domain socket, the name is returnedas a string.

const server = net.createServer((socket) => {  socket.end('goodbye\n');}).on('error',(err) => {// Handle errors here.throw err;});// Grab an arbitrary unused port.server.listen(() => {console.log('opened server on', server.address());});copy

server.address() returnsnull before the'listening' event has beenemitted or after callingserver.close().

server.close([callback])#

• callback<Function> Called when the server is closed.
• Returns:<net.Server>

Stops the server from accepting new connections and keeps existingconnections. This function is asynchronous, the server is finally closedwhen all connections are ended and the server emits a'close' event.The optionalcallback will be called once the'close' event occurs. Unlikethat event, it will be called with anError as its only argument if the serverwas not open when it was closed.

server[Symbol.asyncDispose]()#

Callsserver.close() and returns a promise that fulfills when theserver has closed.

server.getConnections(callback)#

• callback<Function>
• Returns:<net.Server>

Asynchronously get the number of concurrent connections on the server. Workswhen sockets were sent to forks.

Callback should take two argumentserr andcount.

server.listen()#

Start a server listening for connections. Anet.Server can be a TCP oranIPC server depending on what it listens to.

Possible signatures:

• server.listen(handle[, backlog][, callback])
• server.listen(options[, callback])
• server.listen(path[, backlog][, callback])forIPC servers
• server.listen([port[, host[, backlog]]][, callback])for TCP servers

This function is asynchronous. When the server starts listening, the'listening' event will be emitted. The last parametercallbackwill be added as a listener for the'listening' event.

Alllisten() methods can take abacklog parameter to specify the maximumlength of the queue of pending connections. The actual length will be determinedby the OS through sysctl settings such astcp_max_syn_backlog andsomaxconnon Linux. The default value of this parameter is 511 (not 512).

Allnet.Socket are set toSO_REUSEADDR (seesocket(7) fordetails).

Theserver.listen() method can be called again if and only if there was anerror during the firstserver.listen() call orserver.close() has beencalled. Otherwise, anERR_SERVER_ALREADY_LISTEN error will be thrown.

One of the most common errors raised when listening isEADDRINUSE.This happens when another server is already listening on the requestedport/path/handle. One way to handle this would be to retryafter a certain amount of time:

server.on('error',(e) => {if (e.code ==='EADDRINUSE') {console.error('Address in use, retrying...');setTimeout(() => {      server.close();      server.listen(PORT,HOST);    },1000);  }});copy

server.listen({host:'localhost',port:80,exclusive:true,});copy

const controller =newAbortController();server.listen({host:'localhost',port:80,signal: controller.signal,});// Later, when you want to close the server.controller.abort();copy

server.listening#

• Type:<boolean> Indicates whether or not the server is listening for connections.

server.maxConnections#

• Type:<integer>

When the number of connections reaches theserver.maxConnections threshold:

1. If the process is not running in cluster mode, Node.js will close the connection.

2. If the process is running in cluster mode, Node.js will, by default, route the connection to another worker process. To close the connection instead, set [server.dropMaxConnection][] totrue.

It is not recommended to use this option once a socket has been sent to a childwithchild_process.fork().

server.dropMaxConnection#

• Type:<boolean>

Set this property totrue to begin closing connections once the number of connections reaches the [server.maxConnections][] threshold. This setting is only effective in cluster mode.

server.ref()#

• Returns:<net.Server>

Opposite ofunref(), callingref() on a previouslyunrefed server willnot let the program exit if it's the only server left (the default behavior).If the server isrefed callingref() again will have no effect.

server.unref()#

• Returns:<net.Server>

Callingunref() on a server will allow the program to exit if this is the onlyactive server in the event system. If the server is alreadyunrefed callingunref() again will have no effect.

new net.Socket([options])#

• options<Object> Available options are:
  • allowHalfOpen<boolean> If set tofalse, then the socket willautomatically end the writable side when the readable side ends. Seenet.createServer() and the'end' event for details.Default:false.
  • fd<number> If specified, wrap around an existing socket withthe given file descriptor, otherwise a new socket will be created.
  • onread<Object> If specified, incoming data is stored in a singlebufferand passed to the suppliedcallback when data arrives on the socket.This will cause the streaming functionality to not provide any data.The socket will emit events like'error','end', and'close'as usual. Methods likepause() andresume() will also behave asexpected.
    • buffer<Buffer> |<Uint8Array> |<Function> Either a reusable chunk of memory touse for storing incoming data or a function that returns such.
    • callback<Function> This function is called for every chunk of incomingdata. Two arguments are passed to it: the number of bytes written tobuffer and a reference tobuffer. Returnfalse from this function toimplicitlypause() the socket. This function will be executed in theglobal context.
  • readable<boolean> Allow reads on the socket when anfd is passed,otherwise ignored.Default:false.
  • signal<AbortSignal> An Abort signal that may be used to destroy thesocket.
  • writable<boolean> Allow writes on the socket when anfd is passed,otherwise ignored.Default:false.
• Returns:<net.Socket>

Creates a new socket object.

The newly created socket can be either a TCP socket or a streamingIPCendpoint, depending on what itconnect() to.

Event:'close'#

• hadError<boolean>true if the socket had a transmission error.

Emitted once the socket is fully closed. The argumenthadError is a booleanwhich says if the socket was closed due to a transmission error.

Event:'connect'#

Emitted when a socket connection is successfully established.Seenet.createConnection().

Event:'connectionAttempt'#

• ip<string> The IP which the socket is attempting to connect to.
• port<number> The port which the socket is attempting to connect to.
• family<number> The family of the IP. It can be6 for IPv6 or4 for IPv4.

Emitted when a new connection attempt is started. This may be emitted multiple timesif the family autoselection algorithm is enabled insocket.connect(options).

Event:'connectionAttemptFailed'#

• ip<string> The IP which the socket attempted to connect to.
• port<number> The port which the socket attempted to connect to.
• family<number> The family of the IP. It can be6 for IPv6 or4 for IPv4.
• error<Error> The error associated with the failure.

Emitted when a connection attempt failed. This may be emitted multiple timesif the family autoselection algorithm is enabled insocket.connect(options).

Event:'connectionAttemptTimeout'#

• ip<string> The IP which the socket attempted to connect to.
• port<number> The port which the socket attempted to connect to.
• family<number> The family of the IP. It can be6 for IPv6 or4 for IPv4.

Emitted when a connection attempt timed out. This is only emitted (and may beemitted multiple times) if the family autoselection algorithm is enabledinsocket.connect(options).

Event:'data'#

• Type:<Buffer> |<string>

Emitted when data is received. The argumentdata will be aBuffer orString. Encoding of data is set bysocket.setEncoding().

The data will be lost if there is no listener when aSocketemits a'data' event.

Event:'drain'#

Emitted when the write buffer becomes empty. Can be used to throttle uploads.

See also: the return values ofsocket.write().

Event:'end'#

Emitted when the other end of the socket signals the end of transmission, thusending the readable side of the socket.

By default (allowHalfOpen isfalse) the socket will send an end oftransmission packet back and destroy its file descriptor once it has written outits pending write queue. However, ifallowHalfOpen is set totrue, thesocket will not automaticallyend() its writable side,allowing the user to write arbitrary amounts of data. The user must callend() explicitly to close the connection (i.e. sending aFIN packet back).

Event:'error'#

• Type:<Error>

Emitted when an error occurs. The'close' event will be called directlyfollowing this event.

Event:'lookup'#

Emitted after resolving the host name but before connecting.Not applicable to Unix sockets.

• err<Error> |<null> The error object. Seedns.lookup().
• address<string> The IP address.
• family<number> |<null> The address type. Seedns.lookup().
• host<string> The host name.

Event:'ready'#

Emitted when a socket is ready to be used.

Triggered immediately after'connect'.

Event:'timeout'#

Emitted if the socket times out from inactivity. This is only to notify thatthe socket has been idle. The user must manually close the connection.

See also:socket.setTimeout().

socket.address()#

• Returns:<Object>

Returns the boundaddress, the addressfamily name andport of thesocket as reported by the operating system:{ port: 12346, family: 'IPv4', address: '127.0.0.1' }

socket.autoSelectFamilyAttemptedAddresses#

• Type:<string[]>

This property is only present if the family autoselection algorithm is enabled insocket.connect(options) and it is an array of the addresses that have been attempted.

Each address is a string in the form of$IP:$PORT. If the connection was successful,then the last address is the one that the socket is currently connected to.

socket.bufferSize#

• Type:<integer>

This property shows the number of characters buffered for writing. The buffermay contain strings whose length after encoding is not yet known. So this numberis only an approximation of the number of bytes in the buffer.

net.Socket has the property thatsocket.write() always works. This is tohelp users get up and running quickly. The computer cannot always keep upwith the amount of data that is written to a socket. The network connectionsimply might be too slow. Node.js will internally queue up the data written to asocket and send it out over the wire when it is possible.

The consequence of this internal buffering is that memory may grow.Users who experience large or growingbufferSize should attempt to"throttle" the data flows in their program withsocket.pause() andsocket.resume().

socket.bytesRead#

• Type:<integer>

The amount of received bytes.

socket.bytesWritten#

• Type:<integer>

The amount of bytes sent.

socket.connect()#

Initiate a connection on a given socket.

Possible signatures:

• socket.connect(options[, connectListener])
• socket.connect(path[, connectListener])forIPC connections.
• socket.connect(port[, host][, connectListener])for TCP connections.
• Returns:<net.Socket> The socket itself.

This function is asynchronous. When the connection is established, the'connect' event will be emitted. If there is a problem connecting,instead of a'connect' event, an'error' event will be emitted withthe error passed to the'error' listener.The last parameterconnectListener, if supplied, will be added as a listenerfor the'connect' eventonce.

This function should only be used for reconnecting a socket after'close' has been emitted or otherwise it may lead to undefinedbehavior.

socket.connecting#

• Type:<boolean>

Iftrue,socket.connect(options[, connectListener]) wascalled and has not yet finished. It will staytrue until the socket becomesconnected, then it is set tofalse and the'connect' event is emitted. Notethat thesocket.connect(options[, connectListener])callback is a listener for the'connect' event.

socket.destroy([error])#

• error<Object>
• Returns:<net.Socket>

Ensures that no more I/O activity happens on this socket.Destroys the stream and closes the connection.

Seewritable.destroy() for further details.

socket.destroyed#

• Type:<boolean> Indicates if the connection is destroyed or not. Once aconnection is destroyed no further data can be transferred using it.

Seewritable.destroyed for further details.

socket.destroySoon()#

Destroys the socket after all data is written. If the'finish' event wasalready emitted the socket is destroyed immediately. If the socket is stillwritable it implicitly callssocket.end().

socket.end([data[, encoding]][, callback])#

• data<string> |<Buffer> |<Uint8Array>
• encoding<string> Only used when data isstring.Default:'utf8'.
• callback<Function> Optional callback for when the socket is finished.
• Returns:<net.Socket> The socket itself.

Half-closes the socket. i.e., it sends a FIN packet. It is possible theserver will still send some data.

Seewritable.end() for further details.

socket.localAddress#

• Type:<string>

The string representation of the local IP address the remote client isconnecting on. For example, in a server listening on'0.0.0.0', if a clientconnects on'192.168.1.1', the value ofsocket.localAddress would be'192.168.1.1'.

socket.localPort#

• Type:<integer>

The numeric representation of the local port. For example,80 or21.

socket.localFamily#

• Type:<string>

The string representation of the local IP family.'IPv4' or'IPv6'.

socket.pause()#

• Returns:<net.Socket> The socket itself.

Pauses the reading of data. That is,'data' events will not be emitted.Useful to throttle back an upload.

socket.pending#

• Type:<boolean>

This istrue if the socket is not connected yet, either because.connect()has not yet been called or because it is still in the process of connecting(seesocket.connecting).

socket.ref()#

• Returns:<net.Socket> The socket itself.

Opposite ofunref(), callingref() on a previouslyunrefed socket willnot let the program exit if it's the only socket left (the default behavior).If the socket isrefed callingref again will have no effect.

socket.remoteAddress#

• Type:<string>

The string representation of the remote IP address. For example,'74.125.127.100' or'2001:4860:a005::68'. Value may beundefined ifthe socket is destroyed (for example, if the client disconnected).

socket.remoteFamily#

• Type:<string>

The string representation of the remote IP family.'IPv4' or'IPv6'. Value may beundefined ifthe socket is destroyed (for example, if the client disconnected).

socket.remotePort#

• Type:<integer>

The numeric representation of the remote port. For example,80 or21. Value may beundefined ifthe socket is destroyed (for example, if the client disconnected).

socket.resetAndDestroy()#

• Returns:<net.Socket>

Close the TCP connection by sending an RST packet and destroy the stream.If this TCP socket is in connecting status, it will send an RST packet and destroy this TCP socket once it is connected.Otherwise, it will callsocket.destroy with anERR_SOCKET_CLOSED Error.If this is not a TCP socket (for example, a pipe), calling this method will immediately throw anERR_INVALID_HANDLE_TYPE Error.

socket.resume()#

• Returns:<net.Socket> The socket itself.

Resumes reading after a call tosocket.pause().

socket.setEncoding([encoding])#

• encoding<string>
• Returns:<net.Socket> The socket itself.

Set the encoding for the socket as aReadable Stream. Seereadable.setEncoding() for more information.

socket.setKeepAlive([enable][, initialDelay])#

• enable<boolean>Default:false
• initialDelay<number>Default:0
• Returns:<net.Socket> The socket itself.

Enable/disable keep-alive functionality, and optionally set the initialdelay before the first keepalive probe is sent on an idle socket.

SetinitialDelay (in milliseconds) to set the delay between the lastdata packet received and the first keepalive probe. Setting0 forinitialDelay will leave the value unchanged from the default(or previous) setting.

Enabling the keep-alive functionality will set the following socket options:

• SO_KEEPALIVE=1
• TCP_KEEPIDLE=initialDelay
• TCP_KEEPCNT=10
• TCP_KEEPINTVL=1

socket.setNoDelay([noDelay])#

• noDelay<boolean>Default:true
• Returns:<net.Socket> The socket itself.

Enable/disable the use of Nagle's algorithm.

When a TCP connection is created, it will have Nagle's algorithm enabled.

Nagle's algorithm delays data before it is sent via the network. It attemptsto optimize throughput at the expense of latency.

Passingtrue fornoDelay or not passing an argument will disable Nagle'salgorithm for the socket. Passingfalse fornoDelay will enable Nagle'salgorithm.

socket.setTimeout(timeout[, callback])#

• timeout<number>
• callback<Function>
• Returns:<net.Socket> The socket itself.

Sets the socket to timeout aftertimeout milliseconds of inactivity onthe socket. By defaultnet.Socket do not have a timeout.

When an idle timeout is triggered the socket will receive a'timeout'event but the connection will not be severed. The user must manually callsocket.end() orsocket.destroy() to end the connection.

socket.setTimeout(3000);socket.on('timeout',() => {console.log('socket timeout');  socket.end();});copy

Iftimeout is 0, then the existing idle timeout is disabled.

The optionalcallback parameter will be added as a one-time listener for the'timeout' event.

socket.timeout#

• Type:<number> |<undefined>

The socket timeout in milliseconds as set bysocket.setTimeout().It isundefined if a timeout has not been set.

socket.unref()#

• Returns:<net.Socket> The socket itself.

Callingunref() on a socket will allow the program to exit if this is the onlyactive socket in the event system. If the socket is alreadyunrefed callingunref() again will have no effect.

socket.write(data[, encoding][, callback])#

• data<string> |<Buffer> |<Uint8Array>
• encoding<string> Only used when data isstring.Default:utf8.
• callback<Function>
• Returns:<boolean>

Sends data on the socket. The second parameter specifies the encoding in thecase of a string. It defaults to UTF8 encoding.

Returnstrue if the entire data was flushed successfully to the kernelbuffer. Returnsfalse if all or part of the data was queued in user memory.'drain' will be emitted when the buffer is again free.

The optionalcallback parameter will be executed when the data is finallywritten out, which may not be immediately.

SeeWritable streamwrite() method for moreinformation.

socket.readyState#

• Type:<string>

This property represents the state of the connection as a string.

• If the stream is connectingsocket.readyState isopening.
• If the stream is readable and writable, it isopen.
• If the stream is readable and not writable, it isreadOnly.
• If the stream is not readable and writable, it iswriteOnly.

net.connect(options[, connectListener])#

• options<Object>
• connectListener<Function>
• Returns:<net.Socket>

Alias tonet.createConnection(options[, connectListener]).

net.connect(path[, connectListener])#

• path<string>
• connectListener<Function>
• Returns:<net.Socket>

Alias tonet.createConnection(path[, connectListener]).

net.connect(port[, host][, connectListener])#

• port<number>
• host<string>
• connectListener<Function>
• Returns:<net.Socket>

Alias tonet.createConnection(port[, host][, connectListener]).

net.createConnection(options[, connectListener])#

• options<Object> Required. Will be passed to both thenew net.Socket([options]) call and thesocket.connect(options[, connectListener])method.
• connectListener<Function> Common parameter of thenet.createConnection() functions. If supplied, will be added asa listener for the'connect' event on the returned socket once.
• Returns:<net.Socket> The newly created socket used to start the connection.

For available options, seenew net.Socket([options])andsocket.connect(options[, connectListener]).

Additional options:

• timeout<number> If set, will be used to callsocket.setTimeout(timeout) after the socket is created, but beforeit starts the connection.

Following is an example of a client of the echo server describedin thenet.createServer() section:

import netfrom'node:net';const client = net.createConnection({port:8124 },() => {// 'connect' listener.console.log('connected to server!');  client.write('world!\r\n');});client.on('data',(data) => {console.log(data.toString());  client.end();});client.on('end',() => {console.log('disconnected from server');});const net =require('node:net');const client = net.createConnection({port:8124 },() => {// 'connect' listener.console.log('connected to server!');  client.write('world!\r\n');});client.on('data',(data) => {console.log(data.toString());  client.end();});client.on('end',() => {console.log('disconnected from server');});copy

To connect on the socket/tmp/echo.sock:

const client = net.createConnection({path:'/tmp/echo.sock' });copy

Following is an example of a client using theport andonreadoption. In this case, theonread option will be only used to callnew net.Socket([options]) and theport option will be used tocallsocket.connect(options[, connectListener]).

import netfrom'node:net';import {Buffer }from'node:buffer';net.createConnection({port:8124,onread: {// Reuses a 4KiB Buffer for every read from the socket.buffer:Buffer.alloc(4 *1024),callback:function(nread, buf) {// Received data is available in `buf` from 0 to `nread`.console.log(buf.toString('utf8',0, nread));    },  },});const net =require('node:net');net.createConnection({port:8124,onread: {// Reuses a 4KiB Buffer for every read from the socket.buffer:Buffer.alloc(4 *1024),callback:function(nread, buf) {// Received data is available in `buf` from 0 to `nread`.console.log(buf.toString('utf8',0, nread));    },  },});copy

net.createConnection(path[, connectListener])#

• path<string> Path the socket should connect to. Will be passed tosocket.connect(path[, connectListener]).SeeIdentifying paths for IPC connections.
• connectListener<Function> Common parameter of thenet.createConnection() functions, an "once" listener for the'connect' event on the initiating socket. Will be passed tosocket.connect(path[, connectListener]).
• Returns:<net.Socket> The newly created socket used to start the connection.

Initiates anIPC connection.

This function creates a newnet.Socket with all options set to default,immediately initiates connection withsocket.connect(path[, connectListener]),then returns thenet.Socket that starts the connection.

net.createConnection(port[, host][, connectListener])#

• port<number> Port the socket should connect to. Will be passed tosocket.connect(port[, host][, connectListener]).
• host<string> Host the socket should connect to. Will be passed tosocket.connect(port[, host][, connectListener]).Default:'localhost'.
• connectListener<Function> Common parameter of thenet.createConnection() functions, an "once" listener for the'connect' event on the initiating socket. Will be passed tosocket.connect(port[, host][, connectListener]).
• Returns:<net.Socket> The newly created socket used to start the connection.

Initiates a TCP connection.

This function creates a newnet.Socket with all options set to default,immediately initiates connection withsocket.connect(port[, host][, connectListener]),then returns thenet.Socket that starts the connection.