Thinking through timeouts

timeoutTest.js

const https = require('https');

const options = {
  host: 'exoplanetarchive.ipac.caltech.edu',
  path: '/cgi-bin/nstedAPI/nph-nstedAPI?table=exoplanets&select=*&format=json',
  // apply an initial timeout which will apply to the connect event
  timeout: 2000,
};

const beforeRequest = Date.now();

function handleResponse(res) {
  const resReceived = Date.now();
  console.log(
    `${resReceived -
      beforeRequest} ms elapsed between creating req and receiving res`
  );

  // uncomment this line to force a timeout if 20ms elapse between packets
  // req.socket.setTimeout(20);

  // there is no end event unless we listen to the data event
  res.once('data', chunk => {});
  res.on('end', () => {
    console.log(`Entire response received in ${Date.now() - resReceived}`);
  });
}

const req = https.request(options, handleResponse);

// set timeout which will be applied after the connect event is fired
// This particular API can be slow, so sometimes it may take more than 5 seconds to send response
// Tweak this number if you see lots of timeouts before getting the response,
// bring it to a value where you about 25% of the time
req.setTimeout(5000);

req.on('timeout', () => {
  console.error(
    `!!!!! request timeout ${Date.now() -
      beforeRequest} ms before timeout event fired`
  );
  req.abort();
});

req.on('error', () => {});
req.end();