When is the request fired? http.request()

Question

When is the request fired? http.request()

A little question concerning node's http.request(options, callback) method.
I got the following example code from the docs:

var options = {
  hostname: 'www.google.com',
  port: 80,
  path: '/upload',
  method: 'POST'
};

var req = http.request(options, function(res) {
  console.log('STATUS: ' + res.statusCode);
  console.log('HEADERS: ' + JSON.stringify(res.headers));
  res.setEncoding('utf8');
  res.on('data', function (chunk) {
    console.log('BODY: ' + chunk);
  });
});

req.on('error', function(e) {
  console.log('problem with request: ' + e.message);
});

// write data to request body
req.write('data\n');
req.write('data\n');
req.end();

Question: When is the actual HTTP request getting fired?

Is it at the time of assigning the request to the req variable (line 8), or maybe at req.end()?

node.js

Answer 1

The explanation is right in the documentation following the example:

Note that in the example req.end() was called. With http.request() one must always call req.end() to signify that you're done with the request - even if there is no data being written to the request body.

The call of req.end() is mandatory. Note that req is a http.ClientRequest. The documentation of http.ClientRequest.prototype.end gives you the final clue:

request.end([data], [encoding])
Finishes sending the request