new Agent([options])#

• options<Object> Set of configurable options to set on the agent.Can have the following fields:
  • keepAlive<boolean> Keep sockets around even when there are nooutstanding requests, so they can be used for future requests withouthaving to reestablish a TCP connection. Not to be confused with thekeep-alive value of theConnection header. TheConnection: keep-aliveheader is always sent when using an agent except when theConnectionheader is explicitly specified or when thekeepAlive andmaxSocketsoptions are respectively set tofalse andInfinity, in which caseConnection: close will be used.Default:false.
  • keepAliveMsecs<number> When using thekeepAlive option, specifiestheinitial delayfor TCP Keep-Alive packets. Ignored when thekeepAlive option isfalse orundefined.Default:1000.
  • agentKeepAliveTimeoutBuffer<number> Milliseconds to subtract fromthe server-providedkeep-alive: timeout=... hint when determining socketexpiration time. This buffer helps ensure the agent closes the socketslightly before the server does, reducing the chance of sending a requeston a socket that’s about to be closed by the server.Default:1000.
  • maxSockets<number> Maximum number of sockets to allow per host.If the same host opens multiple concurrent connections, each requestwill use new socket until themaxSockets value is reached.If the host attempts to open more connections thanmaxSockets,the additional requests will enter into a pending request queue, andwill enter active connection state when an existing connection terminates.This makes sure there are at mostmaxSockets active connections atany point in time, from a given host.Default:Infinity.
  • maxTotalSockets<number> Maximum number of sockets allowed forall hosts in total. Each request will use a new socketuntil the maximum is reached.Default:Infinity.
  • maxFreeSockets<number> Maximum number of sockets per host to leave openin a free state. Only relevant ifkeepAlive is set totrue.Default:256.
  • scheduling<string> Scheduling strategy to apply when pickingthe next free socket to use. It can be'fifo' or'lifo'.The main difference between the two scheduling strategies is that'lifo'selects the most recently used socket, while'fifo' selectsthe least recently used socket.In case of a low rate of request per second, the'lifo' schedulingwill lower the risk of picking a socket that might have been closedby the server due to inactivity.In case of a high rate of request per second,the'fifo' scheduling will maximize the number of open sockets,while the'lifo' scheduling will keep it as low as possible.Default:'lifo'.
  • timeout<number> Socket timeout in milliseconds.This will set the timeout when the socket is created.
  • proxyEnv<Object> |<undefined> Environment variables for proxy configuration.SeeBuilt-in Proxy Support for details.Default:undefined
    • HTTP_PROXY<string> |<undefined> URL for the proxy server that HTTP requests should use.If undefined, no proxy is used for HTTP requests.
    • HTTPS_PROXY<string> |<undefined> URL for the proxy server that HTTPS requests should use.If undefined, no proxy is used for HTTPS requests.
    • NO_PROXY<string> |<undefined> Patterns specifying the endpointsthat should not be routed through a proxy.
    • http_proxy<string> |<undefined> Same asHTTP_PROXY. If both are set,http_proxy takes precedence.
    • https_proxy<string> |<undefined> Same asHTTPS_PROXY. If both are set,https_proxy takes precedence.
    • no_proxy<string> |<undefined> Same asNO_PROXY. If both are set,no_proxy takes precedence.
  • defaultPort<number> Default port to use when the port is not specifiedin requests.Default:80.
  • protocol<string> The protocol to use for the agent.Default:'http:'.

options insocket.connect() are also supported.

To configure any of them, a customhttp.Agent instance must be created.

import {Agent, request }from'node:http';const keepAliveAgent =newAgent({keepAlive:true });options.agent = keepAliveAgent;request(options, onResponseCallback);const http =require('node:http');const keepAliveAgent =new http.Agent({keepAlive:true });options.agent = keepAliveAgent;http.request(options, onResponseCallback);copy

agent.createConnection(options[, callback])#

• options<Object> Options containing connection details. Checknet.createConnection() for the format of the options. For custom agents,this object is passed to the customcreateConnection function.
• callback<Function> (Optional, primarily for custom agents) A function to becalled by a customcreateConnection implementation when the socket iscreated, especially for asynchronous operations.
  • err<Error> |<null> An error object if socket creation failed.
  • socket<stream.Duplex> The created socket.
• Returns:<stream.Duplex> The created socket. This is returned by the defaultimplementation or by a custom synchronouscreateConnection implementation.If a customcreateConnection uses thecallback for asynchronousoperation, this return value might not be the primary way to obtain the socket.

Produces a socket/stream to be used for HTTP requests.

By default, this function behaves identically tonet.createConnection(),synchronously returning the created socket. The optionalcallback parameter in thesignature isnot used by this default implementation.

However, custom agents may override this method to provide greater flexibility,for example, to create sockets asynchronously. When overridingcreateConnection:

1. Synchronous socket creation: The overriding method can return thesocket/stream directly.
2. Asynchronous socket creation: The overriding method can accept thecallbackand pass the created socket/stream to it (e.g.,callback(null, newSocket)).If an error occurs during socket creation, it should be passed as the firstargument to thecallback (e.g.,callback(err)).

The agent will call the providedcreateConnection function withoptions andthis internalcallback. Thecallback provided by the agent has a signatureof(err, stream).

agent.keepSocketAlive(socket)#

• socket<stream.Duplex>

Called whensocket is detached from a request and could be persisted by theAgent. Default behavior is to:

socket.setKeepAlive(true,this.keepAliveMsecs);socket.unref();returntrue;copy

This method can be overridden by a particularAgent subclass. If thismethod returns a falsy value, the socket will be destroyed instead of persistingit for use with the next request.

Thesocket argument can be an instance of<net.Socket>, a subclass of<stream.Duplex>.

agent.reuseSocket(socket, request)#

• socket<stream.Duplex>
• request<http.ClientRequest>

Called whensocket is attached torequest after being persisted because ofthe keep-alive options. Default behavior is to:

socket.ref();copy

This method can be overridden by a particularAgent subclass.

Thesocket argument can be an instance of<net.Socket>, a subclass of<stream.Duplex>.

agent.destroy()#

Destroy any sockets that are currently in use by the agent.

It is usually not necessary to do this. However, if using anagent withkeepAlive enabled, then it is best to explicitly shut downthe agent when it is no longer needed. Otherwise,sockets might stay open for quite a long time before the serverterminates them.

agent.freeSockets#

• Type:<Object>

An object which contains arrays of sockets currently awaiting use bythe agent whenkeepAlive is enabled. Do not modify.

Sockets in thefreeSockets list will be automatically destroyed andremoved from the array on'timeout'.

agent.getName([options])#

• options<Object> A set of options providing information for name generation
  • host<string> A domain name or IP address of the server to issue therequest to
  • port<number> Port of remote server
  • localAddress<string> Local interface to bind for network connectionswhen issuing the request
  • family<integer> Must be 4 or 6 if this doesn't equalundefined.
• Returns:<string>

Get a unique name for a set of request options, to determine whether aconnection can be reused. For an HTTP agent, this returnshost:port:localAddress orhost:port:localAddress:family. For an HTTPS agent,the name includes the CA, cert, ciphers, and other HTTPS/TLS-specific optionsthat determine socket reusability.

agent.maxFreeSockets#

• Type:<number>

By default set to 256. For agents withkeepAlive enabled, thissets the maximum number of sockets that will be left open in the freestate.

agent.maxSockets#

• Type:<number>

By default set toInfinity. Determines how many concurrent sockets the agentcan have open per origin. Origin is the returned value ofagent.getName().

agent.maxTotalSockets#

• Type:<number>

By default set toInfinity. Determines how many concurrent sockets the agentcan have open. UnlikemaxSockets, this parameter applies across all origins.

agent.requests#

• Type:<Object>

An object which contains queues of requests that have not yet been assigned tosockets. Do not modify.

agent.sockets#

• Type:<Object>

An object which contains arrays of sockets currently in use by theagent. Do not modify.

Event:'abort'#

Emitted when the request has been aborted by the client. This event is onlyemitted on the first call toabort().

Event:'close'#

Indicates that the request is completed, or its underlying connection wasterminated prematurely (before the response completion).

Event:'connect'#

• response<http.IncomingMessage>
• socket<stream.Duplex>
• head<Buffer>

Emitted each time a server responds to a request with aCONNECT method. Ifthis event is not being listened for, clients receiving aCONNECT method willhave their connections closed.

This event is guaranteed to be passed an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specifies a sockettype other than<net.Socket>.

A client and server pair demonstrating how to listen for the'connect' event:

import { createServer, request }from'node:http';import { connect }from'node:net';import {URL }from'node:url';// Create an HTTP tunneling proxyconst proxy =createServer((req, res) => {  res.writeHead(200, {'Content-Type':'text/plain' });  res.end('okay');});proxy.on('connect',(req, clientSocket, head) => {// Connect to an origin serverconst { port, hostname } =newURL(`http://${req.url}`);const serverSocket =connect(port ||80, hostname,() => {    clientSocket.write('HTTP/1.1 200 Connection Established\r\n' +'Proxy-agent: Node.js-Proxy\r\n' +'\r\n');    serverSocket.write(head);    serverSocket.pipe(clientSocket);    clientSocket.pipe(serverSocket);  });});// Now that proxy is runningproxy.listen(1337,'127.0.0.1',() => {// Make a request to a tunneling proxyconst options = {port:1337,host:'127.0.0.1',method:'CONNECT',path:'www.google.com:80',  };const req =request(options);  req.end();  req.on('connect',(res, socket, head) => {console.log('got connected!');// Make a request over an HTTP tunnel    socket.write('GET / HTTP/1.1\r\n' +'Host: www.google.com:80\r\n' +'Connection: close\r\n' +'\r\n');    socket.on('data',(chunk) => {console.log(chunk.toString());    });    socket.on('end',() => {      proxy.close();    });  });});const http =require('node:http');const net =require('node:net');const {URL } =require('node:url');// Create an HTTP tunneling proxyconst proxy = http.createServer((req, res) => {  res.writeHead(200, {'Content-Type':'text/plain' });  res.end('okay');});proxy.on('connect',(req, clientSocket, head) => {// Connect to an origin serverconst { port, hostname } =newURL(`http://${req.url}`);const serverSocket = net.connect(port ||80, hostname,() => {    clientSocket.write('HTTP/1.1 200 Connection Established\r\n' +'Proxy-agent: Node.js-Proxy\r\n' +'\r\n');    serverSocket.write(head);    serverSocket.pipe(clientSocket);    clientSocket.pipe(serverSocket);  });});// Now that proxy is runningproxy.listen(1337,'127.0.0.1',() => {// Make a request to a tunneling proxyconst options = {port:1337,host:'127.0.0.1',method:'CONNECT',path:'www.google.com:80',  };const req = http.request(options);  req.end();  req.on('connect',(res, socket, head) => {console.log('got connected!');// Make a request over an HTTP tunnel    socket.write('GET / HTTP/1.1\r\n' +'Host: www.google.com:80\r\n' +'Connection: close\r\n' +'\r\n');    socket.on('data',(chunk) => {console.log(chunk.toString());    });    socket.on('end',() => {      proxy.close();    });  });});copy

Event:'continue'#

Emitted when the server sends a '100 Continue' HTTP response, usually becausethe request contained 'Expect: 100-continue'. This is an instruction thatthe client should send the request body.

Event:'finish'#

Emitted when the request has been sent. More specifically, this event is emittedwhen the last segment of the request headers and body have been handed off tothe operating system for transmission over the network. It does not imply thatthe server has received anything yet.

Event:'information'#

• info<Object>
  • httpVersion<string>
  • httpVersionMajor<integer>
  • httpVersionMinor<integer>
  • statusCode<integer>
  • statusMessage<string>
  • headers<Object>
  • rawHeaders<string[]>

Emitted when the server sends a 1xx intermediate response (excluding 101Upgrade). The listeners of this event will receive an object containing theHTTP version, status code, status message, key-value headers object,and array with the raw header names followed by their respective values.

import { request }from'node:http';const options = {host:'127.0.0.1',port:8080,path:'/length_request',};// Make a requestconst req =request(options);req.end();req.on('information',(info) => {console.log(`Got information prior to main response:${info.statusCode}`);});const http =require('node:http');const options = {host:'127.0.0.1',port:8080,path:'/length_request',};// Make a requestconst req = http.request(options);req.end();req.on('information',(info) => {console.log(`Got information prior to main response:${info.statusCode}`);});copy

101 Upgrade statuses do not fire this event due to their break from thetraditional HTTP request/response chain, such as web sockets, in-place TLSupgrades, or HTTP 2.0. To be notified of 101 Upgrade notices, listen for the'upgrade' event instead.

Event:'response'#

• response<http.IncomingMessage>

Emitted when a response is received to this request. This event is emitted onlyonce.

Event:'socket'#

• socket<stream.Duplex>

This event is guaranteed to be passed an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specifies a sockettype other than<net.Socket>.

Event:'timeout'#

Emitted when the underlying socket times out from inactivity. This only notifiesthat the socket has been idle. The request must be destroyed manually.

See also:request.setTimeout().

Event:'upgrade'#

• response<http.IncomingMessage>
• socket<stream.Duplex>
• head<Buffer>

Emitted each time a server responds to a request with an upgrade. If thisevent is not being listened for and the response status code is 101 SwitchingProtocols, clients receiving an upgrade header will have their connectionsclosed.

This event is guaranteed to be passed an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specifies a sockettype other than<net.Socket>.

A client server pair demonstrating how to listen for the'upgrade' event.

import httpfrom'node:http';import processfrom'node:process';// Create an HTTP serverconst server = http.createServer((req, res) => {  res.writeHead(200, {'Content-Type':'text/plain' });  res.end('okay');});server.on('upgrade',(req, socket, head) => {  socket.write('HTTP/1.1 101 Web Socket Protocol Handshake\r\n' +'Upgrade: WebSocket\r\n' +'Connection: Upgrade\r\n' +'\r\n');  socket.pipe(socket);// echo back});// Now that server is runningserver.listen(1337,'127.0.0.1',() => {// make a requestconst options = {port:1337,host:'127.0.0.1',headers: {'Connection':'Upgrade','Upgrade':'websocket',    },  };const req = http.request(options);  req.end();  req.on('upgrade',(res, socket, upgradeHead) => {console.log('got upgraded!');    socket.end();    process.exit(0);  });});const http =require('node:http');// Create an HTTP serverconst server = http.createServer((req, res) => {  res.writeHead(200, {'Content-Type':'text/plain' });  res.end('okay');});server.on('upgrade',(req, socket, head) => {  socket.write('HTTP/1.1 101 Web Socket Protocol Handshake\r\n' +'Upgrade: WebSocket\r\n' +'Connection: Upgrade\r\n' +'\r\n');  socket.pipe(socket);// echo back});// Now that server is runningserver.listen(1337,'127.0.0.1',() => {// make a requestconst options = {port:1337,host:'127.0.0.1',headers: {'Connection':'Upgrade','Upgrade':'websocket',    },  };const req = http.request(options);  req.end();  req.on('upgrade',(res, socket, upgradeHead) => {console.log('got upgraded!');    socket.end();    process.exit(0);  });});copy

request.abort()#

Marks the request as aborting. Calling this will cause remaining datain the response to be dropped and the socket to be destroyed.

request.aborted#

• Type:<boolean>

Therequest.aborted property will betrue if the request hasbeen aborted.

request.connection#

• Type:<stream.Duplex>

Seerequest.socket.

request.cork()#

Seewritable.cork().

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

• data<string> |<Buffer> |<Uint8Array>
• encoding<string>
• callback<Function>
• Returns:<this>

Finishes sending the request. If any parts of the body areunsent, it will flush them to the stream. If the request ischunked, this will send the terminating'0\r\n\r\n'.

Ifdata is specified, it is equivalent to callingrequest.write(data, encoding) followed byrequest.end(callback).

Ifcallback is specified, it will be called when the request streamis finished.

request.destroy([error])#

• error<Error> Optional, an error to emit with'error' event.
• Returns:<this>

Destroy the request. Optionally emit an'error' event,and emit a'close' event. Calling this will cause remaining datain the response to be dropped and the socket to be destroyed.

Seewritable.destroy() for further details.

request.finished#

• Type:<boolean>

Therequest.finished property will betrue ifrequest.end()has been called.request.end() will automatically be called if therequest was initiated viahttp.get().

request.flushHeaders()#

Flushes the request headers.

For efficiency reasons, Node.js normally buffers the request headers untilrequest.end() is called or the first chunk of request data is written. Itthen tries to pack the request headers and data into a single TCP packet.

That's usually desired (it saves a TCP round-trip), but not when the firstdata is not sent until possibly much later.request.flushHeaders() bypassesthe optimization and kickstarts the request.

request.getHeader(name)#

• name<string>
• Returns:<any>

Reads out a header on the request. The name is case-insensitive.The type of the return value depends on the arguments provided torequest.setHeader().

request.setHeader('content-type','text/html');request.setHeader('Content-Length',Buffer.byteLength(body));request.setHeader('Cookie', ['type=ninja','language=javascript']);const contentType = request.getHeader('Content-Type');// 'contentType' is 'text/html'const contentLength = request.getHeader('Content-Length');// 'contentLength' is of type numberconst cookie = request.getHeader('Cookie');// 'cookie' is of type string[]copy

request.getHeaderNames()#

• Returns:<string[]>

Returns an array containing the unique names of the current outgoing headers.All header names are lowercase.

request.setHeader('Foo','bar');request.setHeader('Cookie', ['foo=bar','bar=baz']);const headerNames = request.getHeaderNames();// headerNames === ['foo', 'cookie']copy

request.getHeaders()#

• Returns:<Object>

Returns a shallow copy of the current outgoing headers. Since a shallow copyis used, array values may be mutated without additional calls to variousheader-related http module methods. The keys of the returned object are theheader names and the values are the respective header values. All header namesare lowercase.

The object returned by therequest.getHeaders() methoddoes notprototypically inherit from the JavaScriptObject. This means that typicalObject methods such asobj.toString(),obj.hasOwnProperty(), and othersare not defined andwill not work.

request.setHeader('Foo','bar');request.setHeader('Cookie', ['foo=bar','bar=baz']);const headers = request.getHeaders();// headers === { foo: 'bar', 'cookie': ['foo=bar', 'bar=baz'] }copy

request.getRawHeaderNames()#

• Returns:<string[]>

Returns an array containing the unique names of the current outgoing rawheaders. Header names are returned with their exact casing being set.

request.setHeader('Foo','bar');request.setHeader('Set-Cookie', ['foo=bar','bar=baz']);const headerNames = request.getRawHeaderNames();// headerNames === ['Foo', 'Set-Cookie']copy

request.hasHeader(name)#

• name<string>
• Returns:<boolean>

Returnstrue if the header identified byname is currently set in theoutgoing headers. The header name matching is case-insensitive.

const hasContentType = request.hasHeader('content-type');copy

request.maxHeadersCount#

• Type:<number>Default:2000

Limits maximum response headers count. If set to 0, no limit will be applied.

request.path#

• Type:<string> The request path.

request.method#

• Type:<string> The request method.

request.host#

• Type:<string> The request host.

request.protocol#

• Type:<string> The request protocol.

request.removeHeader(name)#

• name<string>

Removes a header that's already defined into headers object.

request.removeHeader('Content-Type');copy

request.reusedSocket#

• Type:<boolean> Whether the request is send through a reused socket.

When sending request through a keep-alive enabled agent, the underlying socketmight be reused. But if server closes connection at unfortunate time, clientmay run into a 'ECONNRESET' error.

import httpfrom'node:http';const agent =new http.Agent({keepAlive:true });// Server has a 5 seconds keep-alive timeout by defaulthttp  .createServer((req, res) => {    res.write('hello\n');    res.end();  })  .listen(3000);setInterval(() => {// Adapting a keep-alive agent  http.get('http://localhost:3000', { agent },(res) => {    res.on('data',(data) => {// Do nothing    });  });},5000);// Sending request on 5s interval so it's easy to hit idle timeoutconst http =require('node:http');const agent =new http.Agent({keepAlive:true });// Server has a 5 seconds keep-alive timeout by defaulthttp  .createServer((req, res) => {    res.write('hello\n');    res.end();  })  .listen(3000);setInterval(() => {// Adapting a keep-alive agent  http.get('http://localhost:3000', { agent },(res) => {    res.on('data',(data) => {// Do nothing    });  });},5000);// Sending request on 5s interval so it's easy to hit idle timeoutcopy

By marking a request whether it reused socket or not, we can doautomatic error retry base on it.

import httpfrom'node:http';const agent =new http.Agent({keepAlive:true });functionretriableRequest() {const req = http    .get('http://localhost:3000', { agent },(res) => {// ...    })    .on('error',(err) => {// Check if retry is neededif (req.reusedSocket && err.code ==='ECONNRESET') {retriableRequest();      }    });}retriableRequest();const http =require('node:http');const agent =new http.Agent({keepAlive:true });functionretriableRequest() {const req = http    .get('http://localhost:3000', { agent },(res) => {// ...    })    .on('error',(err) => {// Check if retry is neededif (req.reusedSocket && err.code ==='ECONNRESET') {retriableRequest();      }    });}retriableRequest();copy

request.setHeader(name, value)#

• name<string>
• value<any>

Sets a single header value for headers object. If this header already exists inthe to-be-sent headers, its value will be replaced. Use an array of stringshere to send multiple headers with the same name. Non-string values will bestored without modification. Therefore,request.getHeader() may returnnon-string values. However, the non-string values will be converted to stringsfor network transmission.

request.setHeader('Content-Type','application/json');copy

or

request.setHeader('Cookie', ['type=ninja','language=javascript']);copy

When the value is a string an exception will be thrown if it containscharacters outside thelatin1 encoding.

If you need to pass UTF-8 characters in the value please encode the valueusing theRFC 8187 standard.

const filename ='Rock 🎵.txt';request.setHeader('Content-Disposition',`attachment; filename*=utf-8''${encodeURIComponent(filename)}`);copy

request.setNoDelay([noDelay])#

• noDelay<boolean>

Once a socket is assigned to this request and is connectedsocket.setNoDelay() will be called.

request.setSocketKeepAlive([enable][, initialDelay])#

• enable<boolean>
• initialDelay<number>

Once a socket is assigned to this request and is connectedsocket.setKeepAlive() will be called.

request.setTimeout(timeout[, callback])#

• timeout<number> Milliseconds before a request times out.
• callback<Function> Optional function to be called when a timeout occurs.Same as binding to the'timeout' event.
• Returns:<http.ClientRequest>

Once a socket is assigned to this request and is connectedsocket.setTimeout() will be called.

request.socket#

• Type:<stream.Duplex>

Reference to the underlying socket. Usually users will not want to accessthis property. In particular, the socket will not emit'readable' eventsbecause of how the protocol parser attaches to the socket.

import httpfrom'node:http';const options = {host:'www.google.com',};const req = http.get(options);req.end();req.once('response',(res) => {const ip = req.socket.localAddress;const port = req.socket.localPort;console.log(`Your IP address is${ip} and your source port is${port}.`);// Consume response object});const http =require('node:http');const options = {host:'www.google.com',};const req = http.get(options);req.end();req.once('response',(res) => {const ip = req.socket.localAddress;const port = req.socket.localPort;console.log(`Your IP address is${ip} and your source port is${port}.`);// Consume response object});copy

This property is guaranteed to be an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specified a sockettype other than<net.Socket>.

request.uncork()#

Seewritable.uncork().

request.writableEnded#

• Type:<boolean>

Istrue afterrequest.end() has been called. This propertydoes not indicate whether the data has been flushed, for this userequest.writableFinished instead.

request.writableFinished#

• Type:<boolean>

Istrue if all data has been flushed to the underlying system, immediatelybefore the'finish' event is emitted.

request.write(chunk[, encoding][, callback])#

• chunk<string> |<Buffer> |<Uint8Array>
• encoding<string>
• callback<Function>
• Returns:<boolean>

Sends a chunk of the body. This method can be called multiple times. If noContent-Length is set, data will automatically be encoded in HTTP Chunkedtransfer encoding, so that server knows when the data ends. TheTransfer-Encoding: chunked header is added. Callingrequest.end()is necessary to finish sending the request.

Theencoding argument is optional and only applies whenchunk is a string.Defaults to'utf8'.

Thecallback argument is optional and will be called when this chunk of datais flushed, but only if the chunk is non-empty.

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 free again.

Whenwrite function is called with empty string or buffer, it doesnothing and waits for more input.

Event:'checkContinue'#

• request<http.IncomingMessage>
• response<http.ServerResponse>

Emitted each time a request with an HTTPExpect: 100-continue is received.If this event is not listened for, the server will automatically respondwith a100 Continue as appropriate.

Handling this event involves callingresponse.writeContinue() if theclient should continue to send the request body, or generating an appropriateHTTP response (e.g. 400 Bad Request) if the client should not continue to sendthe request body.

When this event is emitted and handled, the'request' event willnot be emitted.

Event:'checkExpectation'#

• request<http.IncomingMessage>
• response<http.ServerResponse>

Emitted each time a request with an HTTPExpect header is received, where thevalue is not100-continue. If this event is not listened for, the server willautomatically respond with a417 Expectation Failed as appropriate.

When this event is emitted and handled, the'request' event willnot be emitted.

Event:'clientError'#

• exception<Error>
• socket<stream.Duplex>

If a client connection emits an'error' event, it will be forwarded here.Listener of this event is responsible for closing/destroying the underlyingsocket. For example, one may wish to more gracefully close the socket with acustom HTTP response instead of abruptly severing the connection. The socketmust be closed or destroyed before the listener ends.

This event is guaranteed to be passed an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specifies a sockettype other than<net.Socket>.

Default behavior is to try close the socket with a HTTP '400 Bad Request',or a HTTP '431 Request Header Fields Too Large' in the case of aHPE_HEADER_OVERFLOW error. If the socket is not writable or headersof the current attachedhttp.ServerResponse has been sent, it isimmediately destroyed.

socket is thenet.Socket object that the error originated from.

import httpfrom'node:http';const server = http.createServer((req, res) => {  res.end();});server.on('clientError',(err, socket) => {  socket.end('HTTP/1.1 400 Bad Request\r\n\r\n');});server.listen(8000);const http =require('node:http');const server = http.createServer((req, res) => {  res.end();});server.on('clientError',(err, socket) => {  socket.end('HTTP/1.1 400 Bad Request\r\n\r\n');});server.listen(8000);copy

When the'clientError' event occurs, there is norequest orresponseobject, so any HTTP response sent, including response headers and payload,must be written directly to thesocket object. Care must be taken toensure the response is a properly formatted HTTP response message.

err is an instance ofError with two extra columns:

• bytesParsed: the bytes count of request packet that Node.js may have parsedcorrectly;
• rawPacket: the raw packet of current request.

In some cases, the client has already received the response and/or the sockethas already been destroyed, like in case ofECONNRESET errors. Beforetrying to send data to the socket, it is better to check that it is stillwritable.

server.on('clientError',(err, socket) => {if (err.code ==='ECONNRESET' || !socket.writable) {return;  }  socket.end('HTTP/1.1 400 Bad Request\r\n\r\n');});copy

Event:'close'#

Emitted when the server closes.

Event:'connect'#

• request<http.IncomingMessage> Arguments for the HTTP request, as it is inthe'request' event
• socket<stream.Duplex> Network socket between the server and client
• head<Buffer> The first packet of the tunneling stream (may be empty)

Emitted each time a client requests an HTTPCONNECT method. If this event isnot listened for, then clients requesting aCONNECT method will have theirconnections closed.

This event is guaranteed to be passed an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specifies a sockettype other than<net.Socket>.

After this event is emitted, the request's socket will not have a'data'event listener, meaning it will need to be bound in order to handle datasent to the server on that socket.

Event:'connection'#

• socket<stream.Duplex>

This event is emitted when a new TCP stream is established.socket istypically an object of typenet.Socket. Usually users will not want toaccess this event. In particular, the socket will not emit'readable' eventsbecause of how the protocol parser attaches to the socket. Thesocket canalso be accessed atrequest.socket.

This event can also be explicitly emitted by users to inject connectionsinto the HTTP server. In that case, anyDuplex stream can be passed.

Ifsocket.setTimeout() is called here, the timeout will be replaced withserver.keepAliveTimeout when the socket has served a request (ifserver.keepAliveTimeout is non-zero).

This event is guaranteed to be passed an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specifies a sockettype other than<net.Socket>.

Event:'dropRequest'#

• request<http.IncomingMessage> Arguments for the HTTP request, as it is inthe'request' event
• socket<stream.Duplex> Network socket between the server and client

When the number of requests on a socket reaches the threshold ofserver.maxRequestsPerSocket, the server will drop new requestsand emit'dropRequest' event instead, then send503 to client.

Event:'request'#

• request<http.IncomingMessage>
• response<http.ServerResponse>

Emitted each time there is a request. There may be multiple requestsper connection (in the case of HTTP Keep-Alive connections).

Event:'upgrade'#

• request<http.IncomingMessage> Arguments for the HTTP request, as it is inthe'request' event
• socket<stream.Duplex> Network socket between the server and client
• head<Buffer> The first packet of the upgraded stream (may be empty)

Emitted each time a client's HTTP upgrade request is accepted. By defaultall HTTP upgrade requests are ignored (i.e. only regular'request' eventsare emitted, sticking with the normal HTTP request/response flow) unless youlisten to this event, in which case they are all accepted (i.e. the'upgrade'event is emitted instead, and future communication must handled directlythrough the raw socket). You can control this more precisely by using theservershouldUpgradeCallback option.

Listening to this event is optional and clients cannot insist on a protocolchange.

After this event is emitted, the request's socket will not have a'data'event listener, meaning it will need to be bound in order to handle datasent to the server on that socket.

If an upgrade is accepted byshouldUpgradeCallback but no event handleris registered then the socket is destroyed, resulting in an immediateconnection closure for the client.

This event is guaranteed to be passed an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specifies a sockettype other than<net.Socket>.

server.close([callback])#

• callback<Function>

Stops the server from accepting new connections and closes all connectionsconnected to this server which are not sending a request or waiting fora response.Seenet.Server.close().

const http =require('node:http');const server = http.createServer({keepAliveTimeout:60000 },(req, res) => {  res.writeHead(200, {'Content-Type':'application/json' });  res.end(JSON.stringify({data:'Hello World!',  }));});server.listen(8000);// Close the server after 10 secondssetTimeout(() => {  server.close(() => {console.log('server on port 8000 closed successfully');  });},10000);copy

server.closeAllConnections()#

Closes all established HTTP(S) connections connected to this server, includingactive connections connected to this server which are sending a request orwaiting for a response. This doesnot destroy sockets upgraded to a differentprotocol, such as WebSocket or HTTP/2.

This is a forceful way of closing all connections and should be used withcaution. Whenever using this in conjunction withserver.close, calling thisafterserver.close is recommended as to avoid race conditions where newconnections are created between a call to this and a call toserver.close.

const http =require('node:http');const server = http.createServer({keepAliveTimeout:60000 },(req, res) => {  res.writeHead(200, {'Content-Type':'application/json' });  res.end(JSON.stringify({data:'Hello World!',  }));});server.listen(8000);// Close the server after 10 secondssetTimeout(() => {  server.close(() => {console.log('server on port 8000 closed successfully');  });// Closes all connections, ensuring the server closes successfully  server.closeAllConnections();},10000);copy

server.closeIdleConnections()#

Closes all connections connected to this server which are not sending a requestor waiting for a response.

Starting with Node.js 19.0.0, there's no need for calling this method inconjunction withserver.close to reapkeep-alive connections. Using itwon't cause any harm though, and it can be useful to ensure backwardscompatibility for libraries and applications that need to support versionsolder than 19.0.0. Whenever using this in conjunction withserver.close,calling thisafterserver.close is recommended as to avoid raceconditions where new connections are created between a call to this and acall toserver.close.

const http =require('node:http');const server = http.createServer({keepAliveTimeout:60000 },(req, res) => {  res.writeHead(200, {'Content-Type':'application/json' });  res.end(JSON.stringify({data:'Hello World!',  }));});server.listen(8000);// Close the server after 10 secondssetTimeout(() => {  server.close(() => {console.log('server on port 8000 closed successfully');  });// Closes idle connections, such as keep-alive connections. Server will close// once remaining active connections are terminated  server.closeIdleConnections();},10000);copy

server.headersTimeout#

• Type:<number>Default: The minimum betweenserver.requestTimeout or60000.

Limit the amount of time the parser will wait to receive the complete HTTPheaders.

If the timeout expires, the server responds with status 408 withoutforwarding the request to the request listener and then closes the connection.

It must be set to a non-zero value (e.g. 120 seconds) to protect againstpotential Denial-of-Service attacks in case the server is deployed without areverse proxy in front.

server.listen()#

Starts the HTTP server listening for connections.This method is identical toserver.listen() fromnet.Server.

server.listening#

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

server.maxHeadersCount#

• Type:<number>Default:2000

Limits maximum incoming headers count. If set to 0, no limit will be applied.

server.requestTimeout#

• Type:<number>Default:300000

Sets the timeout value in milliseconds for receiving the entire request fromthe client.

If the timeout expires, the server responds with status 408 withoutforwarding the request to the request listener and then closes the connection.

It must be set to a non-zero value (e.g. 120 seconds) to protect againstpotential Denial-of-Service attacks in case the server is deployed without areverse proxy in front.

server.setTimeout([msecs][, callback])#

• msecs<number>Default: 0 (no timeout)
• callback<Function>
• Returns:<http.Server>

Sets the timeout value for sockets, and emits a'timeout' event onthe Server object, passing the socket as an argument, if a timeoutoccurs.

If there is a'timeout' event listener on the Server object, then itwill be called with the timed-out socket as an argument.

By default, the Server does not timeout sockets. However, if a callbackis assigned to the Server's'timeout' event, timeouts must be handledexplicitly.

server.maxRequestsPerSocket#

• Type:<number> Requests per socket.Default: 0 (no limit)

The maximum number of requests socket can handlebefore closing keep alive connection.

A value of0 will disable the limit.

When the limit is reached it will set theConnection header value toclose,but will not actually close the connection, subsequent requests sentafter the limit is reached will get503 Service Unavailable as a response.

server.timeout#

• Type:<number> Timeout in milliseconds.Default: 0 (no timeout)

The number of milliseconds of inactivity before a socket is presumedto have timed out.

A value of0 will disable the timeout behavior on incoming connections.

The socket timeout logic is set up on connection, so changing thisvalue only affects new connections to the server, not any existing connections.

server.keepAliveTimeout#

• Type:<number> Timeout in milliseconds.Default:5000 (5 seconds).

The number of milliseconds of inactivity a server needs to wait for additionalincoming data, after it has finished writing the last response, before a socketwill be destroyed.

This timeout value is combined with theserver.keepAliveTimeoutBuffer option to determine the actual sockettimeout, calculated as:socketTimeout = keepAliveTimeout + keepAliveTimeoutBufferIf the server receives new data before the keep-alive timeout has fired, itwill reset the regular inactivity timeout, i.e.,server.timeout.

A value of0 will disable the keep-alive timeout behavior on incomingconnections.A value of0 makes the HTTP server behave similarly to Node.js versions priorto 8.0.0, which did not have a keep-alive timeout.

The socket timeout logic is set up on connection, so changing this value onlyaffects new connections to the server, not any existing connections.

server.keepAliveTimeoutBuffer#

• Type:<number> Timeout in milliseconds.Default:1000 (1 second).

An additional buffer time added to theserver.keepAliveTimeout to extend the internal socket timeout.

This buffer helps reduce connection reset (ECONNRESET) errors by increasingthe socket timeout slightly beyond the advertised keep-alive timeout.

This option applies only to new incoming connections.

server[Symbol.asyncDispose]()#

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

Event:'close'#

Indicates that the response is completed, or its underlying connection wasterminated prematurely (before the response completion).

Event:'finish'#

Emitted when the response has been sent. More specifically, this event isemitted when the last segment of the response headers and body have beenhanded off to the operating system for transmission over the network. Itdoes not imply that the client has received anything yet.

response.addTrailers(headers)#

• headers<Object>

This method adds HTTP trailing headers (a header but at the end of themessage) to the response.

Trailers willonly be emitted if chunked encoding is used for theresponse; if it is not (e.g. if the request was HTTP/1.0), they willbe silently discarded.

HTTP requires theTrailer header to be sent in order toemit trailers, with a list of the header fields in its value. E.g.,

response.writeHead(200, {'Content-Type':'text/plain','Trailer':'Content-MD5' });response.write(fileData);response.addTrailers({'Content-MD5':'7895bf4b8828b55ceaf47747b4bca667' });response.end();copy

Attempting to set a header field name or value that contains invalid characterswill result in aTypeError being thrown.

response.connection#

• Type:<stream.Duplex>

Seeresponse.socket.

response.cork()#

Seewritable.cork().

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

• data<string> |<Buffer> |<Uint8Array>
• encoding<string>
• callback<Function>
• Returns:<this>

This method signals to the server that all of the response headers and bodyhave been sent; that server should consider this message complete.The method,response.end(), MUST be called on each response.

Ifdata is specified, it is similar in effect to callingresponse.write(data, encoding) followed byresponse.end(callback).

Ifcallback is specified, it will be called when the response streamis finished.

response.finished#

• Type:<boolean>

Theresponse.finished property will betrue ifresponse.end()has been called.

response.flushHeaders()#

Flushes the response headers. See also:request.flushHeaders().

response.getHeader(name)#

• name<string>
• Returns:<number> |<string> |<string[]> |<undefined>

Reads out a header that's already been queued but not sent to the client.The name is case-insensitive. The type of the return value dependson the arguments provided toresponse.setHeader().

response.setHeader('Content-Type','text/html');response.setHeader('Content-Length',Buffer.byteLength(body));response.setHeader('Set-Cookie', ['type=ninja','language=javascript']);const contentType = response.getHeader('content-type');// contentType is 'text/html'const contentLength = response.getHeader('Content-Length');// contentLength is of type numberconst setCookie = response.getHeader('set-cookie');// setCookie is of type string[]copy

response.getHeaderNames()#

• Returns:<string[]>

Returns an array containing the unique names of the current outgoing headers.All header names are lowercase.

response.setHeader('Foo','bar');response.setHeader('Set-Cookie', ['foo=bar','bar=baz']);const headerNames = response.getHeaderNames();// headerNames === ['foo', 'set-cookie']copy

response.getHeaders()#

• Returns:<Object>

Returns a shallow copy of the current outgoing headers. Since a shallow copyis used, array values may be mutated without additional calls to variousheader-related http module methods. The keys of the returned object are theheader names and the values are the respective header values. All header namesare lowercase.

The object returned by theresponse.getHeaders() methoddoes notprototypically inherit from the JavaScriptObject. This means that typicalObject methods such asobj.toString(),obj.hasOwnProperty(), and othersare not defined andwill not work.

response.setHeader('Foo','bar');response.setHeader('Set-Cookie', ['foo=bar','bar=baz']);const headers = response.getHeaders();// headers === { foo: 'bar', 'set-cookie': ['foo=bar', 'bar=baz'] }copy

response.hasHeader(name)#

• name<string>
• Returns:<boolean>

Returnstrue if the header identified byname is currently set in theoutgoing headers. The header name matching is case-insensitive.

const hasContentType = response.hasHeader('content-type');copy

response.headersSent#

• Type:<boolean>

Boolean (read-only). True if headers were sent, false otherwise.

response.removeHeader(name)#

• name<string>

Removes a header that's queued for implicit sending.

response.removeHeader('Content-Encoding');copy

response.req#

• Type:<http.IncomingMessage>

A reference to the original HTTPrequest object.

response.sendDate#

• Type:<boolean>

When true, the Date header will be automatically generated and sent inthe response if it is not already present in the headers. Defaults to true.

This should only be disabled for testing; HTTP requires the Date headerin responses.

response.setHeader(name, value)#

• name<string>
• value<number> |<string> |<string[]>
• Returns:<http.ServerResponse>

Returns the response object.

Sets a single header value for implicit headers. If this header already existsin the to-be-sent headers, its value will be replaced. Use an array of stringshere to send multiple headers with the same name. Non-string values will bestored without modification. Therefore,response.getHeader() may returnnon-string values. However, the non-string values will be converted to stringsfor network transmission. The same response object is returned to the caller,to enable call chaining.

response.setHeader('Content-Type','text/html');copy

or

response.setHeader('Set-Cookie', ['type=ninja','language=javascript']);copy

Attempting to set a header field name or value that contains invalid characterswill result in aTypeError being thrown.

When headers have been set withresponse.setHeader(), they will be mergedwith any headers passed toresponse.writeHead(), with the headers passedtoresponse.writeHead() given precedence.

// Returns content-type = text/plainconst server = http.createServer((req, res) => {  res.setHeader('Content-Type','text/html');  res.setHeader('X-Foo','bar');  res.writeHead(200, {'Content-Type':'text/plain' });  res.end('ok');});copy

Ifresponse.writeHead() method is called and this method has not beencalled, it will directly write the supplied header values onto the networkchannel without caching internally, and theresponse.getHeader() on theheader will not yield the expected result. If progressive population of headersis desired with potential future retrieval and modification, useresponse.setHeader() instead ofresponse.writeHead().

response.setTimeout(msecs[, callback])#

• msecs<number>
• callback<Function>
• Returns:<http.ServerResponse>

Sets the Socket's timeout value tomsecs. If a callback isprovided, then it is added as a listener on the'timeout' event onthe response object.

If no'timeout' listener is added to the request, the response, orthe server, then sockets are destroyed when they time out. If a handler isassigned to the request, the response, or the server's'timeout' events,timed out sockets must be handled explicitly.

response.socket#

• Type:<stream.Duplex>

Reference to the underlying socket. Usually users will not want to accessthis property. In particular, the socket will not emit'readable' eventsbecause of how the protocol parser attaches to the socket. Afterresponse.end(), the property is nulled.

import httpfrom'node:http';const server = http.createServer((req, res) => {const ip = res.socket.remoteAddress;const port = res.socket.remotePort;  res.end(`Your IP address is${ip} and your source port is${port}.`);}).listen(3000);const http =require('node:http');const server = http.createServer((req, res) => {const ip = res.socket.remoteAddress;const port = res.socket.remotePort;  res.end(`Your IP address is${ip} and your source port is${port}.`);}).listen(3000);copy

This property is guaranteed to be an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specified a sockettype other than<net.Socket>.

response.statusCode#

• Type:<number>Default:200

When using implicit headers (not callingresponse.writeHead() explicitly),this property controls the status code that will be sent to the client whenthe headers get flushed.

response.statusCode =404;copy

After response header was sent to the client, this property indicates thestatus code which was sent out.

response.statusMessage#

• Type:<string>

When using implicit headers (not callingresponse.writeHead() explicitly),this property controls the status message that will be sent to the client whenthe headers get flushed. If this is left asundefined then the standardmessage for the status code will be used.

response.statusMessage ='Not found';copy

After response header was sent to the client, this property indicates thestatus message which was sent out.

response.strictContentLength#

• Type:<boolean>Default:false

If set totrue, Node.js will check whether theContent-Lengthheader value and the size of the body, in bytes, are equal.Mismatching theContent-Length header value will resultin anError being thrown, identified bycode:'ERR_HTTP_CONTENT_LENGTH_MISMATCH'.

response.uncork()#

Seewritable.uncork().

response.writableEnded#

• Type:<boolean>

Istrue afterresponse.end() has been called. This propertydoes not indicate whether the data has been flushed, for this useresponse.writableFinished instead.

response.writableFinished#

• Type:<boolean>

Istrue if all data has been flushed to the underlying system, immediatelybefore the'finish' event is emitted.

response.write(chunk[, encoding][, callback])#

• chunk<string> |<Buffer> |<Uint8Array>
• encoding<string>Default:'utf8'
• callback<Function>
• Returns:<boolean>

If this method is called andresponse.writeHead() has not been called,it will switch to implicit header mode and flush the implicit headers.

This sends a chunk of the response body. This method maybe called multiple times to provide successive parts of the body.

IfrejectNonStandardBodyWrites is set to true increateServerthen writing to the body is not allowed when the request method or responsestatus do not support content. If an attempt is made to write to the body for aHEAD request or as part of a204 or304response, a synchronousErrorwith the codeERR_HTTP_BODY_NOT_ALLOWED is thrown.

chunk can be a string or a buffer. Ifchunk is a string,the second parameter specifies how to encode it into a byte stream.callback will be called when this chunk of data is flushed.

This is the raw HTTP body and has nothing to do with higher-level multi-partbody encodings that may be used.

The first timeresponse.write() is called, it will send the bufferedheader information and the first chunk of the body to the client. The secondtimeresponse.write() is called, Node.js assumes data will be streamed,and sends the new data separately. That is, the response is buffered up to thefirst chunk of the body.

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 free again.

response.writeContinue()#

Sends an HTTP/1.1 100 Continue message to the client, indicating thatthe request body should be sent. See the'checkContinue' event onServer.

response.writeEarlyHints(hints[, callback])#

• hints<Object>
• callback<Function>

Sends an HTTP/1.1 103 Early Hints message to the client with a Link header,indicating that the user agent can preload/preconnect the linked resources.Thehints is an object containing the values of headers to be sent withearly hints message. The optionalcallback argument will be called whenthe response message has been written.

Example

const earlyHintsLink ='</styles.css>; rel=preload; as=style';response.writeEarlyHints({'link': earlyHintsLink,});const earlyHintsLinks = ['</styles.css>; rel=preload; as=style','</scripts.js>; rel=preload; as=script',];response.writeEarlyHints({'link': earlyHintsLinks,'x-trace-id':'id for diagnostics',});constearlyHintsCallback = () =>console.log('early hints message sent');response.writeEarlyHints({'link': earlyHintsLinks,}, earlyHintsCallback);copy

response.writeHead(statusCode[, statusMessage][, headers])#

• statusCode<number>
• statusMessage<string>
• headers<Object> |<Array>
• Returns:<http.ServerResponse>

Sends a response header to the request. The status code is a 3-digit HTTPstatus code, like404. The last argument,headers, are the response headers.Optionally one can give a human-readablestatusMessage as the secondargument.

headers may be anArray where the keys and values are in the same list.It isnot a list of tuples. So, the even-numbered offsets are key values,and the odd-numbered offsets are the associated values. The array is in the sameformat asrequest.rawHeaders.

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

const body ='hello world';response  .writeHead(200, {'Content-Length':Buffer.byteLength(body),'Content-Type':'text/plain',  })  .end(body);copy

This method must only be called once on a message and it mustbe called beforeresponse.end() is called.

Ifresponse.write() orresponse.end() are called before callingthis, the implicit/mutable headers will be calculated and call this function.

When headers have been set withresponse.setHeader(), they will be mergedwith any headers passed toresponse.writeHead(), with the headers passedtoresponse.writeHead() given precedence.

If this method is called andresponse.setHeader() has not been called,it will directly write the supplied header values onto the network channelwithout caching internally, and theresponse.getHeader() on the headerwill not yield the expected result. If progressive population of headers isdesired with potential future retrieval and modification, useresponse.setHeader() instead.

// Returns content-type = text/plainconst server = http.createServer((req, res) => {  res.setHeader('Content-Type','text/html');  res.setHeader('X-Foo','bar');  res.writeHead(200, {'Content-Type':'text/plain' });  res.end('ok');});copy

Content-Length is read in bytes, not characters. UseBuffer.byteLength() to determine the length of the body in bytes. Node.jswill check whetherContent-Length and the length of the body which hasbeen transmitted are equal or not.

Attempting to set a header field name or value that contains invalid characterswill result in aTypeError being thrown.

response.writeProcessing()#

Sends a HTTP/1.1 102 Processing message to the client, indicating thatthe request body should be sent.

Event:'aborted'#

Emitted when the request has been aborted.

Event:'close'#

Emitted when the request has been completed.

message.aborted#

• Type:<boolean>

Themessage.aborted property will betrue if the request hasbeen aborted.

message.complete#

• Type:<boolean>

Themessage.complete property will betrue if a complete HTTP message hasbeen received and successfully parsed.

This property is particularly useful as a means of determining if a client orserver fully transmitted a message before a connection was terminated:

const req = http.request({host:'127.0.0.1',port:8080,method:'POST',},(res) => {  res.resume();  res.on('end',() => {if (!res.complete)console.error('The connection was terminated while the message was still being sent');  });});copy

message.connection#

Alias formessage.socket.

message.destroy([error])#

• error<Error>
• Returns:<this>

Callsdestroy() on the socket that received theIncomingMessage. Iferroris provided, an'error' event is emitted on the socket anderror is passedas an argument to any listeners on the event.

message.headers#

• Type:<Object>

The request/response headers object.

Key-value pairs of header names and values. Header names are lower-cased.

// Prints something like://// { 'user-agent': 'curl/7.22.0',//   host: '127.0.0.1:8000',//   accept: '*/*' }console.log(request.headers);copy

Duplicates in raw headers are handled in the following ways, depending on theheader name:

• Duplicates ofage,authorization,content-length,content-type,etag,expires,from,host,if-modified-since,if-unmodified-since,last-modified,location,max-forwards,proxy-authorization,referer,retry-after,server, oruser-agent are discarded.To allow duplicate values of the headers listed above to be joined,use the optionjoinDuplicateHeaders inhttp.request()andhttp.createServer(). See RFC 9110 Section 5.3 for moreinformation.
• set-cookie is always an array. Duplicates are added to the array.
• For duplicatecookie headers, the values are joined together with;.
• For all other headers, the values are joined together with,.

message.headersDistinct#

• Type:<Object>

Similar tomessage.headers, but there is no join logic and the values arealways arrays of strings, even for headers received just once.

// Prints something like://// { 'user-agent': ['curl/7.22.0'],//   host: ['127.0.0.1:8000'],//   accept: ['*/*'] }console.log(request.headersDistinct);copy

message.httpVersion#

• Type:<string>

In case of server request, the HTTP version sent by the client. In the case ofclient response, the HTTP version of the connected-to server.Probably either'1.1' or'1.0'.

Alsomessage.httpVersionMajor is the first integer andmessage.httpVersionMinor is the second.

message.method#

• Type:<string>

Only valid for request obtained fromhttp.Server.

The request method as a string. Read only. Examples:'GET','DELETE'.

message.rawHeaders#

• Type:<string[]>

The raw request/response headers list exactly as they were received.

The keys and values are in the same list. It isnot alist of tuples. So, the even-numbered offsets are key values, and theodd-numbered offsets are the associated values.

Header names are not lowercased, and duplicates are not merged.

// Prints something like://// [ 'user-agent',//   'this is invalid because there can be only one',//   'User-Agent',//   'curl/7.22.0',//   'Host',//   '127.0.0.1:8000',//   'ACCEPT',//   '*/*' ]console.log(request.rawHeaders);copy

message.rawTrailers#

• Type:<string[]>

The raw request/response trailer keys and values exactly as they werereceived. Only populated at the'end' event.

message.setTimeout(msecs[, callback])#

• msecs<number>
• callback<Function>
• Returns:<http.IncomingMessage>

Callsmessage.socket.setTimeout(msecs, callback).

message.socket#

• Type:<stream.Duplex>

Thenet.Socket object associated with the connection.

With HTTPS support, userequest.socket.getPeerCertificate() to obtain theclient's authentication details.

This property is guaranteed to be an instance of the<net.Socket> class,a subclass of<stream.Duplex>, unless the user specified a sockettype other than<net.Socket> or internally nulled.

message.statusCode#

• Type:<number>

Only valid for response obtained fromhttp.ClientRequest.

The 3-digit HTTP response status code. E.G.404.

message.statusMessage#

• Type:<string>

Only valid for response obtained fromhttp.ClientRequest.

The HTTP response status message (reason phrase). E.G.OK orInternal Server Error.

message.trailers#

• Type:<Object>

The request/response trailers object. Only populated at the'end' event.

message.trailersDistinct#

• Type:<Object>

Similar tomessage.trailers, but there is no join logic and the values arealways arrays of strings, even for headers received just once.Only populated at the'end' event.

message.url#

• Type:<string>

Only valid for request obtained fromhttp.Server.

Request URL string. This contains only the URL that is present in the actualHTTP request. Take the following request:

GET/status?name=ryanHTTP/1.1Accept:text/plaincopy

To parse the URL into its parts:

newURL(`http://${process.env.HOST ??'localhost'}${request.url}`);copy

Whenrequest.url is'/status?name=ryan' andprocess.env.HOST is undefined:

$node>new URL(`http://${process.env.HOST ?? 'localhost'}${request.url}`);URL {  href: 'http://localhost/status?name=ryan',  origin: 'http://localhost',  protocol: 'http:',  username: '',  password: '',  host: 'localhost',  hostname: 'localhost',  port: '',  pathname: '/status',  search: '?name=ryan',  searchParams: URLSearchParams { 'name' => 'ryan' },  hash: ''}copy

Ensure that you setprocess.env.HOST to the server's host name, or considerreplacing this part entirely. If usingreq.headers.host, ensure propervalidation is used, as clients may specify a customHost header.

Event:'drain'#

Emitted when the buffer of the message is free again.

Event:'finish'#

Emitted when the transmission is finished successfully.

Event:'prefinish'#

Emitted afteroutgoingMessage.end() is called.When the event is emitted, all data has been processed but not necessarilycompletely flushed.

outgoingMessage.addTrailers(headers)#

• headers<Object>

Adds HTTP trailers (headers but at the end of the message) to the message.

Trailers willonly be emitted if the message is chunked encoded. If not,the trailers will be silently discarded.

HTTP requires theTrailer header to be sent to emit trailers,with a list of header field names in its value, e.g.

message.writeHead(200, {'Content-Type':'text/plain','Trailer':'Content-MD5' });message.write(fileData);message.addTrailers({'Content-MD5':'7895bf4b8828b55ceaf47747b4bca667' });message.end();copy

Attempting to set a header field name or value that contains invalid characterswill result in aTypeError being thrown.

outgoingMessage.appendHeader(name, value)#

• name<string> Header name
• value<string> |<string[]> Header value
• Returns:<this>

Append a single header value to the header object.

If the value is an array, this is equivalent to calling this method multipletimes.

If there were no previous values for the header, this is equivalent to callingoutgoingMessage.setHeader(name, value).

Depending of the value ofoptions.uniqueHeaders when the client request or theserver were created, this will end up in the header being sent multiple times ora single time with values joined using;.

outgoingMessage.connection#

Alias ofoutgoingMessage.socket.

outgoingMessage.cork()#

Seewritable.cork().

outgoingMessage.destroy([error])#

• error<Error> Optional, an error to emit witherror event
• Returns:<this>

Destroys the message. Once a socket is associated with the messageand is connected, that socket will be destroyed as well.

outgoingMessage.end(chunk[, encoding][, callback])#

• chunk<string> |<Buffer> |<Uint8Array>
• encoding<string> Optional,Default:utf8
• callback<Function> Optional
• Returns:<this>

Finishes the outgoing message. If any parts of the body are unsent, it willflush them to the underlying system. If the message is chunked, it willsend the terminating chunk0\r\n\r\n, and send the trailers (if any).

Ifchunk is specified, it is equivalent to callingoutgoingMessage.write(chunk, encoding), followed byoutgoingMessage.end(callback).

Ifcallback is provided, it will be called when the message is finished(equivalent to a listener of the'finish' event).

outgoingMessage.flushHeaders()#

Flushes the message headers.

For efficiency reason, Node.js normally buffers the message headersuntiloutgoingMessage.end() is called or the first chunk of message datais written. It then tries to pack the headers and data into a single TCPpacket.

It is usually desired (it saves a TCP round-trip), but not when the firstdata is not sent until possibly much later.outgoingMessage.flushHeaders()bypasses the optimization and kickstarts the message.

outgoingMessage.getHeader(name)#

• name<string> Name of header
• Returns:<number> |<string> |<string[]> |<undefined>

Gets the value of the HTTP header with the given name. If that header is notset, the returned value will beundefined.

outgoingMessage.getHeaderNames()#

• Returns:<string[]>

Returns an array containing the unique names of the current outgoing headers.All names are lowercase.

outgoingMessage.getHeaders()#

• Returns:<Object>

Returns a shallow copy of the current outgoing headers. Since a shallowcopy is used, array values may be mutated without additional calls tovarious header-related HTTP module methods. The keys of the returnedobject are the header names and the values are the respective headervalues. All header names are lowercase.

The object returned by theoutgoingMessage.getHeaders() method doesnot prototypically inherit from the JavaScriptObject. This means thattypicalObject methods such asobj.toString(),obj.hasOwnProperty(),and others are not defined and will not work.

outgoingMessage.setHeader('Foo','bar');outgoingMessage.setHeader('Set-Cookie', ['foo=bar','bar=baz']);const headers = outgoingMessage.getHeaders();// headers === { foo: 'bar', 'set-cookie': ['foo=bar', 'bar=baz'] }copy

outgoingMessage.hasHeader(name)#

• name<string>
• Returns:<boolean>

Returnstrue if the header identified byname is currently set in theoutgoing headers. The header name is case-insensitive.

const hasContentType = outgoingMessage.hasHeader('content-type');copy

outgoingMessage.headersSent#

• Type:<boolean>

Read-only.true if the headers were sent, otherwisefalse.

outgoingMessage.pipe()#

Overrides thestream.pipe() method inherited from the legacyStream classwhich is the parent class ofhttp.OutgoingMessage.

Calling this method will throw anError becauseoutgoingMessage is awrite-only stream.

outgoingMessage.removeHeader(name)#

• name<string> Header name

Removes a header that is queued for implicit sending.

outgoingMessage.removeHeader('Content-Encoding');copy

outgoingMessage.setHeader(name, value)#

• name<string> Header name
• value<number> |<string> |<string[]> Header value
• Returns:<this>

Sets a single header value. If the header already exists in the to-be-sentheaders, its value will be replaced. Use an array of strings to send multipleheaders with the same name.

outgoingMessage.setHeaders(headers)#

• headers<Headers> |<Map>
• Returns:<this>

Sets multiple header values for implicit headers.headers must be an instance ofHeaders orMap,if a header already exists in the to-be-sent headers,its value will be replaced.

const headers =newHeaders({foo:'bar' });outgoingMessage.setHeaders(headers);copy

or

const headers =newMap([['foo','bar']]);outgoingMessage.setHeaders(headers);copy

When headers have been set withoutgoingMessage.setHeaders(),they will be merged with any headers passed toresponse.writeHead(),with the headers passed toresponse.writeHead() given precedence.

// Returns content-type = text/plainconst server = http.createServer((req, res) => {const headers =newHeaders({'Content-Type':'text/html' });  res.setHeaders(headers);  res.writeHead(200, {'Content-Type':'text/plain' });  res.end('ok');});copy

outgoingMessage.setTimeout(msecs[, callback])#

• msecs<number>
• callback<Function> Optional function to be called when a timeoutoccurs. Same as binding to thetimeout event.
• Returns:<this>

Once a socket is associated with the message and is connected,socket.setTimeout() will be called withmsecs as the first parameter.

outgoingMessage.socket#

• Type:<stream.Duplex>

Reference to the underlying socket. Usually, users will not want to accessthis property.

After callingoutgoingMessage.end(), this property will be nulled.

outgoingMessage.uncork()#

Seewritable.uncork()

outgoingMessage.writableCorked#

• Type:<number>

The number of timesoutgoingMessage.cork() has been called.

outgoingMessage.writableEnded#

• Type:<boolean>

Istrue ifoutgoingMessage.end() has been called. This property doesnot indicate whether the data has been flushed. For that purpose, usemessage.writableFinished instead.

outgoingMessage.writableFinished#

• Type:<boolean>

Istrue if all data has been flushed to the underlying system.

outgoingMessage.writableHighWaterMark#

• Type:<number>

ThehighWaterMark of the underlying socket if assigned. Otherwise, the defaultbuffer level whenwritable.write() starts returning false (16384).

outgoingMessage.writableLength#

• Type:<number>

The number of buffered bytes.

outgoingMessage.writableObjectMode#

• Type:<boolean>

Alwaysfalse.

outgoingMessage.write(chunk[, encoding][, callback])#

• chunk<string> |<Buffer> |<Uint8Array>
• encoding<string>Default:utf8
• callback<Function>
• Returns:<boolean>

Sends a chunk of the body. This method can be called multiple times.

Theencoding argument is only relevant whenchunk is a string. Defaults to'utf8'.

Thecallback argument is optional and will be called when this chunk of datais flushed.

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

Proxy URL Format#

Proxy URLs can use either HTTP or HTTPS protocols:

• HTTP proxy:http://proxy.example.com:8080
• HTTPS proxy:https://proxy.example.com:8080
• Proxy with authentication:http://username:password@proxy.example.com:8080

NO_PROXY Format#

TheNO_PROXY environment variable supports several formats:

• * - Bypass proxy for all hosts
• example.com - Exact host name match
• .example.com - Domain suffix match (matchessub.example.com)
• *.example.com - Wildcard domain match
• 192.168.1.100 - Exact IP address match
• 192.168.1.1-192.168.1.100 - IP address range
• example.com:8080 - Hostname with specific port

Multiple entries should be separated by commas.

Example#

To start a Node.js process with proxy support enabled for all requests sentthrough the default global agent, either use theNODE_USE_ENV_PROXY environmentvariable:

NODE_USE_ENV_PROXY=1 HTTP_PROXY=http://proxy.example.com:8080 NO_PROXY=localhost,127.0.0.1 node client.jscopy

Or the--use-env-proxy flag.

HTTP_PROXY=http://proxy.example.com:8080 NO_PROXY=localhost,127.0.0.1 node --use-env-proxy client.jscopy

To create a custom agent with built-in proxy support:

const http =require('node:http');// Creating a custom agent with custom proxy support.const agent =new http.Agent({proxyEnv: {HTTP_PROXY:'http://proxy.example.com:8080' } });http.request({hostname:'www.example.com',port:80,path:'/',  agent,},(res) => {// This request will be proxied through proxy.example.com:8080 using the HTTP protocol.console.log(`STATUS:${res.statusCode}`);});copy

Alternatively, the following also works:

const http =require('node:http');// Use lower-cased option name.const agent1 =new http.Agent({proxyEnv: {http_proxy:'http://proxy.example.com:8080' } });// Use values inherited from the environment variables, if the process is started with// HTTP_PROXY=http://proxy.example.com:8080 this will use the proxy server specified// in process.env.HTTP_PROXY.const agent2 =new http.Agent({proxyEnv: process.env });copy