Demos

misc/eventloop-illustration/

http://sequoia.makes.software/eventloop-svg

ABC

• Always
• Be
• asynC

Get Site Headers

var https = require('https');

function getHeadersHTTPS(address, cb){
  https.get(address)
    .on('response', function(response){
      //success! pass `null` error + headers to callback
      cb(null, response.headers);
    })
    .on('error', function(err){
      //error :( pass to callback
      cb(err);
    });
}

var target = 'https://devdocs.io/';

getHeadersHTTPS(target , function(err, headers){
  if(err) return console.error('ERROR: ', err.message);
  console.log(headers);
});

Ensure protocol is HTTPS

var https = require('https');
var url = require('url');

function getHeadersHTTPS(address, cb){

  var protocol = url.parse(address).protocol;
  if(protocol !== 'https:'){
    return cb(new Error('address must be httpS'));
  }

  https.get(address)
    .on('response', //... omitted ...
}

"takes callback" !== "automatically asynchronous"

Make it Asynchronous

  // ...
  if(protocol !== 'https:'){
    return process.nextTick(function(){
      cb(new Error('address must be httpS'));
    }
  }
  // ...

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