LearnYouNode problem.

09_JugglingAsync.js

//THE EXERCISE:
//This problem is the same as the previous problem (HTTP COLLECT) in that you need to use http.get(). 
//However, this time you will be provided with three URLs as the first three command-line arguments.
//You must collect the complete content provided to you by each of the URLs and print it to the console (stdout). 
//You don't need to print out the length, just the data as a String; one line per URL. 
//The catch is that you must print them out in the same order as the URLs are provided to you as command-line arguments.


//MY ISSUE:
//This is problem #9 on LearnYouNode from nodeschool.io
//They've specifically requested I NOT use [async] for this. 
//This program runs well, except for *one* issue. 
//On line 47, there's a callback in the function aSyncMap
//if I put it inside of the forEach function, it returns data as required, but not in the right order. 
//when outside of the forEach, it seems to not get the proper scope of the var "results" 
//Any thoughts? 


var http = require('http');
var bl = require('bl');

var urls = [];

process.argv.slice(2).forEach(function(item){
  urls.push(item)
});

function getter(url, callback){ 
  http.get(url, function(response) {
    response.setEncoding('utf8');
	response.pipe(bl(function(err, data){
      if (err) {
        return callback(err);
      }
	  callback(data.toString());
    }));
  });
}

function aSyncMap(array, getter, callback){
  var results = [];
  var completed = array.length;
  array.forEach(function (item, index){
    getter(item, function(data){
	  results[index] = data;
	  completed -= 1;
	  if (completed === 0){
	  callback(results);
	  }
	});
  });
}

aSyncMap(urls, getter, function(results){
  results.forEach(function(item, index){
  console.log(item);
  });
}); 

Search for 'count down latch' or 'conditional variable'.... or go full javascript and look up Promises.