Co - working with arrays of generators

arrays.js

'use strict';

const request = require('request'),
      promisify = require('es6-promisify'),
      get = promisify(request.get),
      co = require('co'),
      okay = /^2/,
      sites = [
        'https://www.google.com',
        'https://www.twitter.com',
        'https://www.wikipedia.org',
        'https://www.wunderlist.com',
        'https://www.reddit.com'
      ];

function *ping (url) {
  let response;
  try {
    response = yield get(url);
  }
  catch (e) {console.log(e.message);}
  let up = isUp(response);
  return [url, up];
}

function isUp (response) {
  return response ? okay.test(response.statusCode) : false;
}

function logStatuses (statuses) {
  statuses.forEach(function (tuple) {
    console.log(tuple[0], tuple[1] === true ? 'up' : 'down');
  });
}

function *checkSatusesParallel (sites) {
  let then = Date.now();

  let statuses = yield sites.map(ping);

  console.log('parallel', Date.now() - then, 'ms');
  logStatuses(statuses);
}

function *checkSatusesSequential (sites) {
  let then = Date.now();

  let statuses = [];
  for (let site in sites) {
    let status = yield ping(sites[site]);
    statuses.push(status);
  }

  console.log('sequential ', Date.now() - then, 'ms');
  logStatuses(statuses);
}

co(function *main () {
  yield checkSatusesParallel(sites);
  yield checkSatusesSequential(sites);
  // You can also run both checks in parallel:
  // yield [checkSatusesParallel(sites), checkSatusesSequential(sites)];
})();