jugglingAsync.js

/**
 *  # LEARN YOU THE NODE.JS FOR MUCH WIN!

 ## JUGGLING ASYNC (Exercise 9 of 13)

 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.

 ─────────────────────────────────────────────────────────────────────────────

 ## HINTS

 Don't expect these three servers to play nicely! They are not going to
 give you complete responses in the order you hope, so you can't naively
 just print the output as you get it because they will be out of order.

 You will need to queue the results and keep track of how many of the URLs
 have returned their entire contents. Only once you have them all, you can
 print the data to the console.

 Counting callbacks is one of the fundamental ways of managing async in
 Node. Rather than doing it yourself, you may find it more convenient to
 rely on a third-party library such as [async](https://npmjs.com/async) or
 [after](https://npmjs.com/after). But for this exercise, try and do it
 without any external helper library.
 */

var http = require('http');

var urls = process.argv.slice(2);
var results = [];

// initialise results array
for (i = 0; i < urls.length; i++) {
    results[i] = null;
}

for (i = 0; i < urls.length; i++) {
    (function(i) {
        http.get(urls[i], function(request) {
            var result = "";
            request.setEncoding("utf8");
            request.on("data", function(data) {
                result += data;
            });
            request.on("end", function() {
                results[i] = result;
                var resultCount = 0;
                for (j = 0; j < results.length; j++) {
                    if (results[j] != null) resultCount++;
                }
                if (resultCount == results.length) {
                    for (j = 0; j < results.length; j++) {
                        console.log(results[j]);
                    }
                }
            });
        });
    })(i);
}

/*
*  var http = require('http')
 var bl = require('bl')
 var results = []
 var count = 0

 function printResults () {
 for (var i = 0; i < 3; i++) {
 console.log(results[i])
 }
 }

 function httpGet (index) {
 http.get(process.argv[2 + index], function (response) {
 response.pipe(bl(function (err, data) {
 if (err) {
 return console.error(err)
 }

 results[index] = data.toString()
 count++

 if (count === 3) {
 printResults()
 }
 }))
 })
 }

 for (var i = 0; i < 3; i++) {
 httpGet(i)
 }
* */