nodejs request library, get the response time

Question

Using the nodejs request library: https://github.com/mikeal/request

var request = require(\'request\');
request(\'http://example.com\', function (er         


        

Answer 1

The request library can do timing for you (docs):

request.get({
  url : 'http://example.com',
  time : true
},function(err, response){
  console.log('Request time in ms', response.elapsedTime);
});

As the question implies, you could get issues with the approach of starting a timer, calling request then stopping the timer in the callback:

var start = new Date();
request.get('http://example.com', function(err, response){
  // NOT GOOD
  console.log('Request time plus 5 seconds', new Date() - start);
});
require('sleep').sleep(5); // time-consuming synchronous action

Answer 2

Something like

var timedReq = function(url, next) {
  var start = new Date();
  request(url, function(err, res, body) {
    res.responseTime = new Date() - start;
    next(err, res, body);
  });
};

will do it for you. This seems small enough that it's probably easier than finding a new library.

Answer 3

Instead of using Date() you could also use process.hrtime. I have a library specifically for these kind of cases that uses hrtime. The library name is exectimer.

You could use it like this:

var timedReq = function(url, next) {
  var tick = new t.Tick("responseTime");
  tick.start();
  request(url, function(err, res, body) {
    tick.stop();
    next(err, res, body);
  });
};

// when ready check the results with this:
var responseTime = t.timers.responseTime;
console.log(responseTime.min()); // minimal response time
console.log(responseTime.max()); // minimal response time
console.log(responseTime.mean()); // mean response time
console.log(responseTime.median()); // median response time