ReadonlyclosedIs true after 'close' has been emitted.
ReadonlyconnectionSee response.socket.
Is true after writable.destroy() has been called.
ReadonlyerroredReturns error if the stream has been destroyed with an error.
ReadonlyfinishedBoolean value that indicates whether the response has completed. Starts
as false. After response.end() executes, the value will be true.
ReadonlyheadersTrue if headers were sent, false otherwise (read-only).
ReadonlyreqA reference to the original HTTP2 request object.
When true, the Date header will be automatically generated and sent in the response if it is not already present in the headers. Defaults to true.
This should only be disabled for testing; HTTP requires the Date header in responses.
ReadonlysocketReturns a Proxy object that acts as a net.Socket (or tls.TLSSocket) but
applies getters, setters, and methods based on HTTP/2 logic.
destroyed, readable, and writable properties will be retrieved from and
set on response.stream.
destroy, emit, end, on and once methods will be called on response.stream.
setTimeout method will be called on response.stream.session.
pause, read, resume, and write will throw an error with code ERR_HTTP2_NO_SOCKET_MANIPULATION. See Http2Session and Sockets for
more information.
All other interactions will be routed directly to the socket.
import http2 from 'node:http2';
const server = http2.createServer((req, res) => {
const ip = req.socket.remoteAddress;
const port = req.socket.remotePort;
res.end(`Your IP address is ${ip} and your source port is ${port}.`);
}).listen(3000);
When using implicit headers (not calling response.writeHead() explicitly),
this property controls the status code that will be sent to the client when
the headers get flushed.
response.statusCode = 404;
After response header was sent to the client, this property indicates the status code which was sent out.
Status message is not supported by HTTP/2 (RFC 7540 8.1.2.4). It returns an empty string.
ReadonlystreamThe Http2Stream object backing the response.
Is true if it is safe to call writable.write(), which means
the stream has not been destroyed, errored, or ended.
ReadonlywritableReturns whether the stream was destroyed or errored before emitting 'finish'.
ReadonlywritableNumber of times writable.uncork() needs to be
called in order to fully uncork the stream.
ReadonlywritableIs true after writable.end() has been called. This property
does not indicate whether the data has been flushed, for this use writable.writableFinished instead.
ReadonlywritableIs set to true immediately before the 'finish' event is emitted.
ReadonlywritableReturn the value of highWaterMark passed when creating this Writable.
ReadonlywritableThis property contains the number of bytes (or objects) in the queue
ready to be written. The value provides introspection data regarding
the status of the highWaterMark.
ReadonlywritableIs true if the stream's buffer has been full and stream will emit 'drain'.
ReadonlywritableGetter for the property objectMode of a given Writable stream.
Optional_Optional_Calls writable.destroy() with an AbortError and returns
a promise that fulfills when the stream is finished.
Optional[captureThe Symbol.for('nodejs.rejection') method is called in case a
promise rejection happens when emitting an event and
captureRejections is enabled on the emitter.
It is possible to use events.captureRejectionSymbol in
place of Symbol.for('nodejs.rejection').
import { EventEmitter, captureRejectionSymbol } from 'node:events';
class MyClass extends EventEmitter {
constructor() {
super({ captureRejections: true });
}
[captureRejectionSymbol](err, event, ...args) {
console.log('rejection happened for', event, 'with', err, ...args);
this.destroy(err);
}
destroy(err) {
// Tear the resource down here.
}
}
Alias for emitter.on(eventName, listener).
This method adds HTTP trailing headers (a header but at the end of the message) to the response.
Attempting to set a header field name or value that contains invalid characters
will result in a TypeError being thrown.
Append a single header value to the header object.
If the value is an array, this is equivalent to calling this method multiple times.
If there were no previous values for the header, this is equivalent to calling setHeader.
Attempting to set a header field name or value that contains invalid characters will result in a TypeError being thrown.
// Returns headers including "set-cookie: a" and "set-cookie: b"
const server = http2.createServer((req, res) => {
res.setHeader('set-cookie', 'a');
res.appendHeader('set-cookie', 'b');
res.writeHead(200);
res.end('ok');
});
The writable.cork() method forces all written data to be buffered in memory.
The buffered data will be flushed when either the uncork or end methods are called.
The primary intent of writable.cork() is to accommodate a situation in which
several small chunks are written to the stream in rapid succession. Instead of
immediately forwarding them to the underlying destination, writable.cork() buffers all the chunks until writable.uncork() is called, which will pass them
all to writable._writev(), if present. This prevents a head-of-line blocking
situation where data is being buffered while waiting for the first small chunk
to be processed. However, use of writable.cork() without implementing writable._writev() may have an adverse effect on throughput.
See also: writable.uncork(), writable._writev().
Call http2stream.pushStream() with the given headers, and wrap the
given Http2Stream on a newly created Http2ServerResponse as the callback
parameter if successful. When Http2ServerRequest is closed, the callback is
called with an error ERR_HTTP2_INVALID_STREAM.
An object describing the headers
Called once http2stream.pushStream() is finished, or either when the attempt to create the pushed Http2Stream has failed or has been rejected, or the state of
Http2ServerRequest is closed prior to calling the http2stream.pushStream() method
Destroy the stream. Optionally emit an 'error' event, and emit a 'close' event (unless emitClose is set to false). After this call, the writable
stream has ended and subsequent calls to write() or end() will result in
an ERR_STREAM_DESTROYED error.
This is a destructive and immediate way to destroy a stream. Previous calls to write() may not have drained, and may trigger an ERR_STREAM_DESTROYED error.
Use end() instead of destroy if data should flush before close, or wait for
the 'drain' event before destroying the stream.
Once destroy() has been called any further calls will be a no-op and no
further errors except from _destroy() may be emitted as 'error'.
Implementors should not override this method,
but instead implement writable._destroy().
Optionalerror: ErrorOptional, an error to emit with 'error' event.
Synchronously calls each of the listeners registered for the event named
eventName, in the order they were registered, passing the supplied arguments
to each.
Returns true if the event had listeners, false otherwise.
import { EventEmitter } from 'node:events';
const myEmitter = new EventEmitter();
// First listener
myEmitter.on('event', function firstListener() {
console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(arg1, arg2) {
console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...args) {
const parameters = args.join(', ');
console.log(`event with parameters ${parameters} in third listener`);
});
console.log(myEmitter.listeners('event'));
myEmitter.emit('event', 1, 2, 3, 4, 5);
// Prints:
// [
// [Function: firstListener],
// [Function: secondListener],
// [Function: thirdListener]
// ]
// Helloooo! first listener
// event with parameters 1, 2 in second listener
// event with parameters 1, 2, 3, 4, 5 in third listener
This method signals to the server that all of the response headers and body
have been sent; that server should consider this message complete.
The method, response.end(), MUST be called on each response.
If data is specified, it is equivalent to calling response.write(data, encoding) followed by response.end(callback).
If callback is specified, it will be called when the response stream
is finished.
Optionalcallback: () => voidThis method signals to the server that all of the response headers and body
have been sent; that server should consider this message complete.
The method, response.end(), MUST be called on each response.
If data is specified, it is equivalent to calling response.write(data, encoding) followed by response.end(callback).
If callback is specified, it will be called when the response stream
is finished.
Optionalcallback: () => voidThis method signals to the server that all of the response headers and body
have been sent; that server should consider this message complete.
The method, response.end(), MUST be called on each response.
If data is specified, it is equivalent to calling response.write(data, encoding) followed by response.end(callback).
If callback is specified, it will be called when the response stream
is finished.
Optionalcallback: () => voidReturns an array listing the events for which the emitter has registered listeners.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});
const sym = Symbol('symbol');
myEE.on(sym, () => {});
console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]
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']
Returns a shallow copy of the current outgoing headers. Since a shallow copy is used, array values may be mutated without additional calls to various header-related http module methods. The keys of the returned object are the header names and the values are the respective header values. All header names are lowercase.
The object returned by the response.getHeaders() method does not prototypically inherit from the JavaScript Object. This means that typical Object methods such as obj.toString(),
obj.hasOwnProperty(), and others
are not defined and will 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'] }
Returns the number of listeners listening for the event named eventName.
If listener is provided, it will return how many times the listener is found
in the list of the listeners of the event.
The name of the event being listened for
Optionallistener: (...args: WritableEventMap[E]) => voidThe event handler function
Optionallistener: (...args: any[]) => voidReturns a copy of the array of listeners for the event named eventName.
server.on('connection', (stream) => {
console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]
Alias for emitter.removeListener().
Adds the listener function to the end of the listeners array for the
event named eventName. No checks are made to see if the listener has
already been added. Multiple calls passing the same combination of eventName
and listener will result in the listener being added, and called, multiple
times.
server.on('connection', (stream) => {
console.log('someone connected!');
});
Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The
emitter.prependListener() method can be used as an alternative to add the
event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
The name of the event.
The callback function
Adds a one-time listener function for the event named eventName. The
next time eventName is triggered, this listener is removed and then invoked.
server.once('connection', (stream) => {
console.log('Ah, we have our first user!');
});
Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The
emitter.prependOnceListener() method can be used as an alternative to add the
event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
The name of the event.
The callback function
Optionaloptions: PipeOptionsAdds the listener function to the beginning of the listeners array for the
event named eventName. No checks are made to see if the listener has
already been added. Multiple calls passing the same combination of eventName
and listener will result in the listener being added, and called, multiple
times.
server.prependListener('connection', (stream) => {
console.log('someone connected!');
});
Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
The callback function
Adds a one-time listener function for the event named eventName to the
beginning of the listeners array. The next time eventName is triggered, this
listener is removed, and then invoked.
server.prependOnceListener('connection', (stream) => {
console.log('Ah, we have our first user!');
});
Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
The callback function
Returns a copy of the array of listeners for the event named eventName,
including any wrappers (such as those created by .once()).
import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.once('log', () => console.log('log once'));
// Returns a new Array with a function `onceWrapper` which has a property
// `listener` which contains the original listener bound above
const listeners = emitter.rawListeners('log');
const logFnWrapper = listeners[0];
// Logs "log once" to the console and does not unbind the `once` event
logFnWrapper.listener();
// Logs "log once" to the console and removes the listener
logFnWrapper();
emitter.on('log', () => console.log('log persistently'));
// Will return a new Array with a single function bound by `.on()` above
const newListeners = emitter.rawListeners('log');
// Logs "log persistently" twice
newListeners[0]();
emitter.emit('log');
Removes all listeners, or those of the specified eventName.
It is bad practice to remove listeners added elsewhere in the code,
particularly when the EventEmitter instance was created by some other
component or module (e.g. sockets or file streams).
Returns a reference to the EventEmitter, so that calls can be chained.
OptionaleventName: EOptionaleventName: string | symbolRemoves the specified listener from the listener array for the event named
eventName.
const callback = (stream) => {
console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);
removeListener() will remove, at most, one instance of a listener from the
listener array. If any single listener has been added multiple times to the
listener array for the specified eventName, then removeListener() must be
called multiple times to remove each instance.
Once an event is emitted, all listeners attached to it at the
time of emitting are called in order. This implies that any
removeListener() or removeAllListeners() calls after emitting and
before the last listener finishes execution will not remove them from
emit() in progress. Subsequent events behave as expected.
import { EventEmitter } from 'node:events';
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();
const callbackA = () => {
console.log('A');
myEmitter.removeListener('event', callbackB);
};
const callbackB = () => {
console.log('B');
};
myEmitter.on('event', callbackA);
myEmitter.on('event', callbackB);
// callbackA removes listener callbackB but it will still be called.
// Internal listener array at time of emit [callbackA, callbackB]
myEmitter.emit('event');
// Prints:
// A
// B
// callbackB is now removed.
// Internal listener array [callbackA]
myEmitter.emit('event');
// Prints:
// A
Because listeners are managed using an internal array, calling this will
change the position indexes of any listener registered after the listener
being removed. This will not impact the order in which listeners are called,
but it means that any copies of the listener array as returned by
the emitter.listeners() method will need to be recreated.
When a single function has been added as a handler multiple times for a single
event (as in the example below), removeListener() will remove the most
recently added instance. In the example the once('ping')
listener is removed:
import { EventEmitter } from 'node:events';
const ee = new EventEmitter();
function pong() {
console.log('pong');
}
ee.on('ping', pong);
ee.once('ping', pong);
ee.removeListener('ping', pong);
ee.emit('ping');
ee.emit('ping');
Returns a reference to the EventEmitter, so that calls can be chained.
The writable.setDefaultEncoding() method sets the default encoding for a Writable stream.
The new default encoding
Sets a single header value for implicit headers. If this header already exists in the to-be-sent headers, its value will be replaced. Use an array of strings here to send multiple headers with the same name.
response.setHeader('Content-Type', 'text/html; charset=utf-8');
or
response.setHeader('Set-Cookie', ['type=ninja', 'language=javascript']);
Attempting to set a header field name or value that contains invalid characters
will result in a TypeError being thrown.
When headers have been set with response.setHeader(), they will be merged
with any headers passed to response.writeHead(), with the headers passed
to response.writeHead() given precedence.
// Returns content-type = text/plain
const server = http2.createServer((req, res) => {
res.setHeader('Content-Type', 'text/html; charset=utf-8');
res.setHeader('X-Foo', 'bar');
res.writeHead(200, { 'Content-Type': 'text/plain; charset=utf-8' });
res.end('ok');
});
By default EventEmitters will print a warning if more than 10 listeners are
added for a particular event. This is a useful default that helps finding
memory leaks. The emitter.setMaxListeners() method allows the limit to be
modified for this specific EventEmitter instance. The value can be set to
Infinity (or 0) to indicate an unlimited number of listeners.
Returns a reference to the EventEmitter, so that calls can be chained.
Sets the Http2Stream's timeout value to msecs. If a callback is
provided, then it is added as a listener on the 'timeout' event on
the response object.
If no 'timeout' listener is added to the request, the response, or
the server, then Http2Stream s are destroyed when they time out. If a
handler is assigned to the request, the response, or the server's 'timeout' events, timed out sockets must be handled explicitly.
Optionalcallback: () => voidThe writable.uncork() method flushes all data buffered since cork was called.
When using writable.cork() and writable.uncork() to manage the buffering
of writes to a stream, defer calls to writable.uncork() using process.nextTick(). Doing so allows batching of all writable.write() calls that occur within a given Node.js event
loop phase.
stream.cork();
stream.write('some ');
stream.write('data ');
process.nextTick(() => stream.uncork());
If the writable.cork() method is called multiple times on a stream, the
same number of calls to writable.uncork() must be called to flush the buffered
data.
stream.cork();
stream.write('some ');
stream.cork();
stream.write('data ');
process.nextTick(() => {
stream.uncork();
// The data will not be flushed until uncork() is called a second time.
stream.uncork();
});
See also: writable.cork().
If this method is called and response.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 may be called multiple times to provide successive parts of the body.
In the node:http module, the response body is omitted when the
request is a HEAD request. Similarly, the 204 and 304 responses must not include a message body.
chunk can be a string or a buffer. If chunk is a string,
the second parameter specifies how to encode it into a byte stream.
By default the encoding is 'utf8'. 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-part body encodings that may be used.
The first time response.write() is called, it will send the buffered
header information and the first chunk of the body to the client. The second
time response.write() is called, Node.js assumes data will be streamed,
and sends the new data separately. That is, the response is buffered up to the
first chunk of the body.
Returns true if the entire data was flushed successfully to the kernel
buffer. Returns false if all or part of the data was queued in user memory.'drain' will be emitted when the buffer is free again.
Optionalcallback: (err: Error) => voidIf this method is called and response.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 may be called multiple times to provide successive parts of the body.
In the node:http module, the response body is omitted when the
request is a HEAD request. Similarly, the 204 and 304 responses must not include a message body.
chunk can be a string or a buffer. If chunk is a string,
the second parameter specifies how to encode it into a byte stream.
By default the encoding is 'utf8'. 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-part body encodings that may be used.
The first time response.write() is called, it will send the buffered
header information and the first chunk of the body to the client. The second
time response.write() is called, Node.js assumes data will be streamed,
and sends the new data separately. That is, the response is buffered up to the
first chunk of the body.
Returns true if the entire data was flushed successfully to the kernel
buffer. Returns false if all or part of the data was queued in user memory.'drain' will be emitted when the buffer is free again.
Optionalcallback: (err: Error) => voidSends a status 103 Early Hints to the client with a Link header,
indicating that the user agent can preload/preconnect the linked resources.
The hints is an object containing the values of headers to be sent with
early hints message.
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,
});
Sends a response header to the request. The status code is a 3-digit HTTP
status code, like 404. The last argument, headers, are the response headers.
Returns a reference to the Http2ServerResponse, so that calls can be chained.
For compatibility with HTTP/1, a human-readable statusMessage may be
passed as the second argument. However, because the statusMessage has no
meaning within HTTP/2, the argument will have no effect and a process warning
will be emitted.
const body = 'hello world';
response.writeHead(200, {
'Content-Length': Buffer.byteLength(body),
'Content-Type': 'text/plain; charset=utf-8',
});
Content-Length is given in bytes not characters. TheBuffer.byteLength() API may be used to determine the number of bytes in a
given encoding. On outbound messages, Node.js does not check if Content-Length
and the length of the body being transmitted are equal or not. However, when
receiving messages, Node.js will automatically reject messages when the Content-Length does not match the actual payload size.
This method may be called at most one time on a message before response.end() is called.
If response.write() or response.end() are called before calling
this, the implicit/mutable headers will be calculated and call this function.
When headers have been set with response.setHeader(), they will be merged
with any headers passed to response.writeHead(), with the headers passed
to response.writeHead() given precedence.
// Returns content-type = text/plain
const server = http2.createServer((req, res) => {
res.setHeader('Content-Type', 'text/html; charset=utf-8');
res.setHeader('X-Foo', 'bar');
res.writeHead(200, { 'Content-Type': 'text/plain; charset=utf-8' });
res.end('ok');
});
Attempting to set a header field name or value that contains invalid characters
will result in a TypeError being thrown.
Optionalheaders: OutgoingHttpHeaders | readonly string[]Sends a response header to the request. The status code is a 3-digit HTTP
status code, like 404. The last argument, headers, are the response headers.
Returns a reference to the Http2ServerResponse, so that calls can be chained.
For compatibility with HTTP/1, a human-readable statusMessage may be
passed as the second argument. However, because the statusMessage has no
meaning within HTTP/2, the argument will have no effect and a process warning
will be emitted.
const body = 'hello world';
response.writeHead(200, {
'Content-Length': Buffer.byteLength(body),
'Content-Type': 'text/plain; charset=utf-8',
});
Content-Length is given in bytes not characters. TheBuffer.byteLength() API may be used to determine the number of bytes in a
given encoding. On outbound messages, Node.js does not check if Content-Length
and the length of the body being transmitted are equal or not. However, when
receiving messages, Node.js will automatically reject messages when the Content-Length does not match the actual payload size.
This method may be called at most one time on a message before response.end() is called.
If response.write() or response.end() are called before calling
this, the implicit/mutable headers will be calculated and call this function.
When headers have been set with response.setHeader(), they will be merged
with any headers passed to response.writeHead(), with the headers passed
to response.writeHead() given precedence.
// Returns content-type = text/plain
const server = http2.createServer((req, res) => {
res.setHeader('Content-Type', 'text/html; charset=utf-8');
res.setHeader('X-Foo', 'bar');
res.writeHead(200, { 'Content-Type': 'text/plain; charset=utf-8' });
res.end('ok');
});
Attempting to set a header field name or value that contains invalid characters
will result in a TypeError being thrown.
Optionalheaders: OutgoingHttpHeaders | readonly string[]StaticfromA utility method for creating a Writable from a web WritableStream.
Optionaloptions: Pick<StatictoA utility method for creating a web WritableStream from a Writable.
This object is created internally by an HTTP server, not by the user. It is passed as the second parameter to the
'request'event.Since
v8.4.0