Developing over the YouTube API with JSON

I will skip a lot of the boring HTML so that we can focus more deeply on the YouTube response and how we handle this in JavaScript. The most important HTML section you should recognize is the navigation along with the inner videos content div. I have used specific IDs so that we can target each element and check whenever the user clicks a link, then display that content inside #videos.

 <nav id="usersnav">
<ul>
<li><a href="#gotreehouse">gotreehouse</a></li>
<li><a href="#thenextweb">thenextweb</a></li>
<li><a href="#TEDxTalks">TEDxTalks</a></li>
<li><a href="#wearechange">wearechange</a></li>
<li><a href="#RTAmerica">RTAmerica</a></li>
<li><a href="#G4ZDTechTV2">G4ZDTechTV2</a></li>
<li><a href="#NovaCrystallisDotCom">NovaCrystallisDotCom</a></li>
</ul>
</nav>
<div id="videos">
<!-- vids go here -->
</div>

In order for the whole process to work we will need a copy of the latest jQuery library. My demo includes this file from within the ./js/ directory so you won’t need to re-download anything. Also I have kept my custom-written jQuery codes inside the index file instead of moving them to an external JS script. It would obviously be easier to do so when you are running this on a live website, but for my demo it is quicker to study these codes from within the same page.
Pulling Results with jQuery
The first step is to define a set of variables which we need in the script. Then we can handle a click event from the user which is interfacing with any of the navigation links. Each of the anchor elements is using an HREF value containing a hash symbol plus username we need. It is important that we stop this default href from loading by using e.preventDefault() and then pull the value out so we can get the YouTube feed results.

$(function(){
$('#usersnav ul li a').on('click', function(e){
e.preventDefault();
var htmlString = '<ul id="videoslisting">';
var channelname = $(this).attr('href').substring(1);
var ytapiurl = 'http://gdata.youtube.com/feeds/api/users/'+channelname+'/uploads?alt=json&max-results=10';

The handy JavaScript substring() method will create a new string variable starting from the character marker 1(marker 0 is the first character). This removes our hash symbol so that we can now place the username into a generic API call which looks like this:http://gdata.youtube.com/feeds/api/users/CHANNELNAME/uploads?alt=json&max-results=10
The user’s channel name can be accessed to query YouTube and pull out their latest uploads. I am referencing a max results value of 10 and since we are not using pagination. I have not included any other callback methods, either. JSON is the response type we need so that way it’ll be easier parsing all this content inside jQuery.

Building a Loop
PHP and Rails and other programming languages often use logic loops to iterate through data patterns. While loops, for loops, do loops, and other common ideas are not as strict when you would compare them with JavaScript. However the methods for .parseJSON() and jQuery.each()offer the perfect system for looping through all of these results.

$.getJSON(ytapiurl, function(data) {
$.each(data.feed.entry, function(i, item) { 
var title = item['title']['$t'];
var videoid = item['id']['$t'];

var pubdate = item['published']['$t'];
var fulldate = new Date(pubdate).toLocaleDateString();

var thumbimg = item['media$group']['media$thumbnail'][0]['url'];
var tinyimg1 = item['media$group']['media$thumbnail'][1]['url'];
var tinyimg2 = item['media$group']['media$thumbnail'][2]['url'];
var tinyimg3 = item['media$group']['media$thumbnail'][3]['url'];

var vlink = item['media$group']['media$content'][0]['url'];
var ytlink = item['media$group']['media$player'][0]['url'];
var numviews = item['yt$statistics']['viewCount'];
var numcomms = item['gd$comments']['gd$feedLink']['countHint'];

htmlString +='<li class="clearfix"><h2>' + title + '</h2>';
htmlString +='<div class="videothumb"><a href="' + ytlink + '" target="_blank"><img src="' + thumbimg + '" width="480" height="360"></a></div>';
htmlString +='<div class="meta"><p>Published on <strong>' + fulldate + '</strong></p><p>Total views: <strong>' + commafy(numviews) + '</strong></p><p>Total comments: <strong>'+ numcomms +'</strong></p><p><a href="'+ ytlink +'" class="external" target="_blank">View on YouTube</a></p><p><a href="'+ vlink +'" class="external" target="_blank">View in Fullscreen</a></p><p><strong>Alternate Thumbnails</strong>:<br><img src="'+ tinyimg1 +'"> <img src="' + tinyimg2 + '"> <img src="'+ tinyimg3 +'"></p></div></li>';
}); // end each loop

$('#videos').html(htmlString + "</ul>");
}); // end json parsing

This code block seems very large but the majority of the content is generating variable names. YouTube will return a lot more information than we need so it would be foolish to create an array containing all the keys. Instead we should make new variables strictly for the content which will be used inside the layout, and then we create a final HTML string to return to the browser.
Each variable block will contain an important section of the final display. We will need the video title, original publishing date, the full-size thumbnail along with each of the 3 mini-thumbs, direct video URL, view count, and also the comments count. The HTML is displayed using an unordered list of items which finishes by applying the HTML content into the #videos container. This is easily accomplished by using the jQuery .html() method.

Parsing & Formatting Numbers
One other final point I’d like to bring up is the ability to parse through each view counter. Return data for videos which have over 1000 views will not include the comma between each set of 3 numbers. I found an excellent solution on Stack Overflow written using pure JavaScript. The function name is commafy() which is wrapped around each of the view count numbers. This will check if the digits are higher than 4 and automatically place a comma where it should be.
These codes are wonderful to use in any number of JavaScript solutions. The questions and solutions on Stack Overflow are always helpful with these kinds of matters. I think it is worth noting that you could write a much simpler function using jQuery or handling this method inside the .each() loop. But if everything is kept inside a separate file then you may not worry as much about the syntax or number of lines.

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Sumber http://blog.teamtreehouse.com

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