options in socket.connect() are also supported.

Node.js maintains several connections per server to make HTTP requests. This function allows one to transparently issue requests.

url can be a string or a URL object. If url is a string, it is automatically parsed with new URL(). If it is a URL object, it will be automatically converted to an ordinary options object.

If both url and options are specified, the objects are merged, with the options properties taking precedence.

The optional callback parameter will be added as a one-time listener for the 'response' event.

http.request() returns an instance of the ClientRequest class. The ClientRequest instance is a writable stream. If one needs to upload a file with a POST request, then write to the ClientRequest object.

import http from 'node:http';
import { Buffer } from 'node:buffer';

const postData = JSON.stringify({
  'msg': 'Hello World!',
});

const options = {
  hostname: 'www.google.com',
  port: 80,
  path: '/upload',
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Content-Length': Buffer.byteLength(postData),
  },
};

const req = http.request(options, (res) => {
  console.log(`STATUS: ${res.statusCode}`);
  console.log(`HEADERS: ${JSON.stringify(res.headers)}`);
  res.setEncoding('utf8');
  res.on('data', (chunk) => {
    console.log(`BODY: ${chunk}`);
  });
  res.on('end', () => {
    console.log('No more data in response.');
  });
});

req.on('error', (e) => {
  console.error(`problem with request: ${e.message}`);
});

// Write data to request body
req.write(postData);
req.end();

In the example req.end() was called. With http.request() one must always call req.end() to signify the end of the request - even if there is no data being written to the request body.

If any error is encountered during the request (be that with DNS resolution, TCP level errors, or actual HTTP parse errors) an 'error' event is emitted on the returned request object. As with all 'error' events, if no listeners are registered the error will be thrown.

There are a few special headers that should be noted.

• Sending a 'Connection: keep-alive' will notify Node.js that the connection to the server should be persisted until the next request.
• Sending a 'Content-Length' header will disable the default chunked encoding.
• Sending an 'Expect' header will immediately send the request headers. Usually, when sending 'Expect: 100-continue', both a timeout and a listener for the 'continue' event should be set. See RFC 2616 Section 8.2.3 for more information.
• Sending an Authorization header will override using the auth option to compute basic authentication.

Example using a URL as options:

const options = new URL('http://abc:xyz@example.com');

const req = http.request(options, (res) => {
  // ...
});

In a successful request, the following events will be emitted in the following order:

• 'socket'
• 'response'
  • 'data' any number of times, on the res object ('data' will not be emitted at all if the response body is empty, for instance, in most redirects)
  • 'end' on the res object
• 'close'

In the case of a connection error, the following events will be emitted:

• 'socket'
• 'error'
• 'close'

In the case of a premature connection close before the response is received, the following events will be emitted in the following order:

• 'socket'
• 'error' with an error with message 'Error: socket hang up' and code 'ECONNRESET'
• 'close'

In the case of a premature connection close after the response is received, the following events will be emitted in the following order:

• 'socket'
• 'response'
  • 'data' any number of times, on the res object
• (connection closed here)
• 'aborted' on the res object
• 'close'
• 'error' on the res object with an error with message 'Error: aborted' and code 'ECONNRESET'
• 'close' on the res object

If req.destroy() is called before a socket is assigned, the following events will be emitted in the following order:

• (req.destroy() called here)
• 'error' with an error with message 'Error: socket hang up' and code 'ECONNRESET', or the error with which req.destroy() was called
• 'close'

If req.destroy() is called before the connection succeeds, the following events will be emitted in the following order:

• 'socket'
• (req.destroy() called here)
• 'error' with an error with message 'Error: socket hang up' and code 'ECONNRESET', or the error with which req.destroy() was called
• 'close'

If req.destroy() is called after the response is received, the following events will be emitted in the following order:

• 'socket'
• 'response'
  • 'data' any number of times, on the res object
• (req.destroy() called here)
• 'aborted' on the res object
• 'close'
• 'error' on the res object with an error with message 'Error: aborted' and code 'ECONNRESET', or the error with which req.destroy() was called
• 'close' on the res object

If req.abort() is called before a socket is assigned, the following events will be emitted in the following order:

• (req.abort() called here)
• 'abort'
• 'close'

If req.abort() is called before the connection succeeds, the following events will be emitted in the following order:

• 'socket'
• (req.abort() called here)
• 'abort'
• 'error' with an error with message 'Error: socket hang up' and code 'ECONNRESET'
• 'close'

If req.abort() is called after the response is received, the following events will be emitted in the following order:

• 'socket'
• 'response'
  • 'data' any number of times, on the res object
• (req.abort() called here)
• 'abort'
• 'aborted' on the res object
• 'error' on the res object with an error with message 'Error: aborted' and code 'ECONNRESET'.
• 'close'
• 'close' on the res object

Setting the timeout option or using the setTimeout() function will not abort the request or do anything besides add a 'timeout' event.

Passing an AbortSignal and then calling abort() on the corresponding AbortController will behave the same way as calling .destroy() on the request. Specifically, the 'error' event will be emitted with an error with the message 'AbortError: The operation was aborted', the code 'ABORT_ERR' and the cause, if one was provided.