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More APIs: writing your own code (2)

*** This blog post has been originally published in ACRL TechConnect 0n October 9, 2012. ***

My previous post “The simpest AJAX: writing your own code (1)” discussed a few Javascript and JQuery examples that make the use of the Flickr API. In this post, I try out APIs from providers other than Flickr. The examples will look plain to you since I didn’t add any CSS to dress them up. But remember that the focus here is not in presentation but in getting the data out and re-displaying it on your own. Once you get comfortable with this process, you can start thinking about a creative and useful way in which you can present and mash up the same data. We will go through 5 examples I created with three different APIs.  Before taking a look at the codes, check out the results below first.

I. Pinboard API

The first example is Pinboard. Many libraries moved their bookmarks in Del.icio.us to a different site when there was a rumor that Del.cio.us may be shut down by Yahoo. One of those sites were Pinboard.  By getting your bookmark feeds from Pinboard and manipulating them, you can easily present a subset of your bookmark as part of your website.

(a) Display bookmarks in Pinboard using its API

The following page uses JQuery to access the JSONP feed of my public bookmarks in Pinboard. $.ajax() method is invoked on line 13. Line 15, jsonp:”cb”, gives the name to a callback function that will wrap the JSON feed data in it. Note line 18 where I print out data received into the console. This way, you can check if you are receiving JSONP feed in the console of Firebug. Line 19-22 uses $.each() function to access each element in the JSONP feed and the .append() method to add each bookmark’s title and url to the “pinboard” div. JQuery documentation has detailed explanation and examples for its functions and methods. So make sure to check it out if you have any questions about a JQuery function or method.

Pinboard API – example 1

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Pinboard: JSONP-AJAX Example</title>
<script type="text/javascript" src="http://jqueryjs.googlecode.com/files/jquery-1.3.2.min.js"></script>
</head>
<body>
<p> This page takes the JSON feed from <a href="http://pinboard.in/u:bohyunkim/">my public links in Pinboard</a> and re-presents them here. See <a href="http://feeds.pinboard.in/json/u:bohyunkim/">the Pinboard's JSON feed of my links</a>.</p>
<div id="pinboard"><h1>All my links in Pinboard</h1></div>
<script>
$(document).ready(function(){	
$.ajax({
  url:'http://feeds.pinboard.in/json/u:bohyunkim',
  jsonp:"cb",
  dataType:'jsonp',
  success: function(data) {
  	console.log(data); //dumps the data to the console to check if the callback is made successfully
    $.each(data, function(index, item){
      $('#pinboard').append('<div><a href="' + item.u + '">' + item.d
+ '</a></div>');
      }); //each
    } //success
  }); //ajax

});//ready
</script>
</body>
</html>

Here is the screenshot of the page. I opened up the Console window of the Firebug (since I dumped the received in line 18) and you can see the incoming data here. (Note. Click the images to see the large version.)

But it is much more convenient to see the organization and hierarchy of the JSONP feed in the Net panel of Firebug.

And each element of the JSONP feed can be drilled down for further details by clicking the object in each row.

(b) Display only a certain number of bookmarks

Now, let’s display only five bookmarks. In order to do this, only one more line is needed. Line 9 checks the position of each element and breaks the loop when the 5th element is processed.

Pinboard API – example 2

$.ajax({
  url:'http://feeds.pinboard.in/json/u:bohyunkim',
  jsonp:"cb",
  dataType:'jsonp',
  success: function(data) {
    $.each(data, function(index, item){
      	$('#pinboard').append('<div><a href="' + item.u + '">' + item.d
+ '</a></div>');
    	if (index == 4) return false; //only display 5 items
      }); //each
    } //success
  }); //ajax

(c) Display bookmarks with a certain tag

Often libraries want to display bookmarks with a particular tag. Here I add a line using JQuery method $.inArray() to display only bookmarks tagged with ‘fiu.’ $.inArray()  method takes value and array as parameters and returns 0 if the value is found in the array otherwise -1. Line 7 checks if the tag array of a bookmark (item.t) does include ‘fiu,’ and only in such case displays the bookmark. As a result, only the bookmarks with the tag ‘fiu’ are shown in the page.

Pinboard API – example 3

$.ajax({
  url:'http://feeds.pinboard.in/json/u:bohyunkim',
  jsonp:"cb",
  dataType:'jsonp',
  success: function(data) {
    $.each(data, function(index, item){
    	if ($.inArray("fiu", item.t)!==-1) // if the tag is 'fiu'
      		$('#pinboard').append('<div><a href="' + item.u + '">' + item.d
+ '</a></div>');
	}); //each
    } //success
  }); //ajax

II. Reddit API

My second example uses Reddit API. Reddit is a site where people comment on news items of interest. Here I used $.getJSON() instead of $.ajax() in order to process the JSONP feed from the Science section of Reddit. In the case of Pinboard API, I could not find out a way to construct a link that includes a call back function in the url. Some of the parameters had to be specified such as jsonp:”cb”, dataType:’jsonp’. For this reason, I needed to use $.ajax() function. On the other hand, in Reddit, getting the JSONP feed url was straightforward: http://www.reddit.com/r/science/.json?jsonp=cb.

Line 19 adds a title of the page. Line 20-22 extracts the title and link to the news article that is being commented and displays it. Under the news item, the link to the comments for that article in Reddit is added as a bullet item. You can see that, in Line 17 and 18, I have used the console to check if I get the right data and targeting the element I want and then commented out later.

This is just an example, and for that reason, the result is a rather simplified version of the original Reddit page with less information. But as long as you are comfortable accessing and manipulating data at different levels of the JSONP feed sent from an API, you can slice and dice the data in a way that suits your purpose best. So in order to make a clever mash-up, not only the technical coding skills but also your creative ideas of what different sets of data and information to connect and present to offer something new that has not been available or apparent before.

My second example uses Reddit API. Reddit is a site where people comment on news items of interest. Here I used $.getJSON() method instead of $.ajax() in order to process the JSONP feed from the Science section of Reddit. In the case of Pinboard API, I could not find out a way to construct a link for a call back function. Some of the parameters had to be specified such as jsonp:”cb”, dataType:’jsonp’. So I needed to use $.ajax() method.

On the other hand, in Reddit, getting the JSONP feed url was straightforward: http://www.reddit.com/r/science/.json?jsonp=cb.   Line 19 adds a title of the page. Line 20-22 extracts the title and link to the news article that is being commented and displays it. Under the news item, the link to the comments for that article in Reddit is added as a bullet item.You can see that in Line 17 and 18, I have used the console to check if I get the right data and targeting the element I want.

This is just an example, and for that reason, the result is rather a simplified version of the original Reddit page with less information. But as long as you are comfortable accessing and manipulating data at different levels of the JSONP feed sent from an API, you can slice and dice the data in a way that suits your purpose best.

Reddit API – example

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Reddit-Science: JSONP-AJAX Example</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js"></script>
</head>

<body>
<p> This page takes the JSONP feed from <a href="http://www.reddit.com/r/science/">Reddit's Science section</a> and presents the link to the original article and the comments in Reddit to the article as a pair. See <a href="http://www.reddit.com/r/science/.json?jsonp=?">JSONP feed</a> from Reddit.</p>

<div id="feed"> </div>
<script type="text/javascript">
	//run function to parse json response, grab title, link, and media values, and then place in html tags
$(document).ready(function(){		
	$.getJSON('http://www.reddit.com/r/science/.json?jsonp=?', function(rd){
		//console.log(rd);
		//console.log(rd.data.children[0].data.title);
		$('#feed').html('<h1>*Subredditum Scientiae*</h1>');
		$.each(rd.data.children, function(k, v){
      		$('#feed').append('<div><p>'+(k+1)+': <a href="' + v.data.url + '">' + v.data.title+'</a></p><ul><li style="font-variant:small-caps;font-size:small"><a href="http://www.reddit.com'+v.data.permalink+'">Comments from Reddit</a></li></ul></div>');
      }); //each
	}); //getJSON
});//ready	
</script>

</body>
</html>

The structure of a JSON feed can be confusing to make out particularly. So make sure to use the Firebug Net window to figure out the organization of the feed content and the property name for the value you want.

But what if the site from which you would like to get data doesn’t offer JSONP feed? Fortunately you can convert any RSS or XML feed into JSONP feed. Let’s take a look!

III. PubMed Feed with Yahoo Pipes API

Consider this PubMed search. This is simple search that looks for items in PubMed that has to do with Florida International University College of Medicine where I work. You may want to access the data feed of this search result, manipulate, and display in your library website. So far, we have performed a similar task with the Pinboard and the Reddit API using JQuery. But unfortunately PubMed does not offer any JSON feed. We only get RSS feed instead from PubMed.

This is OK, however. You can either manipulate the RSS feed directly or convert the RSS feed into JSON, which you are more familiar with now. Yahoo Pipes is a handy tool for just that purpose. You can do the following tasks with Yahoo Pipes:

  • combine many feeds into one, then sort, filter and translate it.
  • geocode your favorite feeds and browse the items on an interactive map.
  • power widgets/badges on your web site.
  • grab the output of any Pipes as RSS, JSON, KML, and other formats.

Furthermore, there may be a pipe that has been already created for exactly what you want to do by someone else. As PubMed is a popular resource, I found a pipe for PubMed search. I tested, copied the pipe, and changed the search term. Here is the screenshot of my Yahoo Pipe.

If you want to change the pipe, you can click “View Source” and make further changes. Here I just changed the search terms and saved the pipe.

After that, you want to get the results of the Pipe as JSON. If you hover over the “Get as JSON” link in the first screenshot above, you will get a link: http://pipes.yahoo.com/pipes/pipe.run?_id=e176c4da7ae8574bfa5c452f9bb0da92&_render=json&limit=100&term=”Florida International University” and “College of Medicine” But this returns JSON, not JSONP.

In order to get that JSON feed wrapped into a callback function, you need to add this bit, &_callback=myCallback, at the end of the url: http://pipes.yahoo.com/pipes/pipe.run?_id=e176c4da7ae8574bfa5c452f9bb0da92&_render=json&limit=10&term=%22Florida+International+University%22+and+%22College+of+Medicine%22&_callback=myCallback. Now the JSON feed appears wrapped in a callback function like this: myCallback( ). See the difference?

Line 25 enables you to bring in this JSONP feed and invokes the callback function named “myCallback.” Line 14-23 defines this callback function to process the received feed. Line 18-20 takes the JSON data received at the level of data.value. item, and prints out each item’s title (item.title) with a link (item.link). Here I am giving a number for each item by (index+1). If you don’t put +1, the index will begin from 0 instead of 1. Line 21 stops the process when the processed item reaches 5 in number.

Yahoo Pipes API/PubMed – example

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>PubMed and Yahoo Pipes: JSONP-AJAX Example</title>
<script type="text/javascript" src="http://jqueryjs.googlecode.com/files/jquery-1.3.2.min.js"></script>
</head>
<body>
<p> This page takes the JSONP feed from <a href="http://pipes.yahoo.com/pipes/pipe.info?_id=e176c4da7ae8574bfa5c452f9bb0da92"> a Yahoo Pipe</a>, which creates JSONP feed out of a PubMed search results and re-presents them here. 
<br/>See <a href="http://pipes.yahoo.com/pipes/pipe.run?_id=e176c4da7ae8574bfa5c452f9bb0da92&_render=json&limit=10&term=%22Florida+International+University%22+and+%22College+of+Medicine%22&_callback=myCallback">the Yahoo Pipe's JSON feed</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed?term=%22Florida%20International%20University%22%20and%20%22College%20of%20Medicine%22">the original search results in PubMed</a>.</p>
<div id="feed"></div>
<script type="text/javascript">
	//run function to parse json response, grab title, link, and media values - place in html tags
	function myCallback(data) {
		//console.log(data);
		//console.log(data.count);
		$("#feed").html('<h1>The most recent 5 publications from <br/>Florida International University College of Medicine</h1><h2>Results from PubMed</h2>');
		$.each(data.value.items, function(index, item){
      		$('#feed').append('<p>'+(index+1)+': <a href="' + item.link + '">' + item.title
+ '</a></p>');
        if (index == 4) return false; //display the most recent five items
      }); //each
	} //function
	</script>
<script type="text/javascript" src="http://pipes.yahoo.com/pipes/pipe.run?_id=e176c4da7ae8574bfa5c452f9bb0da92&_render=json&limit=10&term=%22Florida+International+University%22+and+%22College+of+Medicine%22&_callback=myCallback"></script>
</body>
</html>

Do you feel more comfortable now with APIs? With a little bit of JQuery and JSON, I was able to make a good use of third-party APIs. Next time, I will try the Worldcat Search API, which is closer to the library world and see how that works.

The simplest AJAX: writing your own code (1)

*** This blog post has been originally published in ACRL TechConnect 0n September 12, 2012. ***

It has been 8 months since the Code Year project started. Back in January, I have provided some tips. Now I want to check in to see if how well you have been following along. Falling behind? You are not alone. Luckily there are still 3-4 months left.

Teaching oneself how to code is not easy. One of the many challenges is keeping at it on a regular basis. Both at home and at work, there seems to be always a dozen things higher in priority than code lessons. Another problem is that often we start a learning project by reading a book with some chosen examples. The Code Year project is somewhat better since it provides interactive tutorials. But at the end of many tutorials, you may have experienced the nagging feeling of doubt about whether you can now go out to the real world and make something that works. Have you done any real-time project yet?

If you are like me, the biggest obstacle in starting your own first small coding project is not so much the lack of knowledge as the fantasy that you still have yet more to learn before trying any such real-life-ish project. I call this ‘fantasy’ because there is never such a time when you are in full possession of knowledge before jumping into a project. In most cases, you discover what you need to learn only after you start a project and run into a problem that you need to solve.

So for this blog post, I tried building something very small. During the process, I had to fight constantly with the feeling that I should go back to the Code Year Project and take those comforting lessons in Javascript and JQeury that I didn’t have time to work through yet. But I also knew that I would be so much more motivated to keep learning if I can just see myself making something on my own. I decided to try some very simple AJAX stuff and started by looking at two examples on the Web. Here I will share those examples and my review process that enabled me to write my own bit of code. After looking at these, I was able to use different APIs to get the same result. My explanation below is intentionally detailed for beginners. But if you can understand the examples without my line-by-line explanation, feel free to skip and go directly to the last section where the challenge is. For what would your AJAX skill be useful? There are a lot of useful data in the cloud. Using AJAX, you can dynamically display your library’s photos stored in Flickr in your library’s website or generate a custom bibliography on the fly using the tags in Pinboard or MESH (Medical Subject Heading) and other filters in PubMed. You can mash up data feeds from multiple providers and create something completely new and interesting such as HealthMap, iSpiecies, and Housing Maps.

Warm-up 1: Jason’s Flickr API example

I found this example, “Flickr API – Display Photos (JSON)” quite useful. This example is at Jason Clark’s website. Jason has many cool code examples and working programs under the Code & Files page. You can see the source of the whole HTML page here . But let’s see the JS part below.

<script type="text/javascript">
//run function to parse json response, grab title, link, and media values - place in html tags
function jsonFlickrFeed(fr) {
    var container = document.getElementById("feed");
    var markup = '<h1>' + '<a href="' + fr.link+ '">' + fr.title + '</a>'+ '</h1>';
    for (var i = 0; i < fr.items.length; i++) {
    markup += '<a title="' + fr.items[i].title + '" href="' + fr.items[i].link + '"><img src="' + fr.items[i].media.m + '" alt="' + fr.items[i].title + '"></a>';
}
container.innerHTML = markup;
}
</script>
<script type="text/javascript" src="http://api.flickr.com/services/feeds/photos_public.gne?tags=cil2009&format=json">
</script>

After spending a few minutes looking at the source of the page, you can figure out the following:

  • Line 12 imports data formatted in JSON from Flickr, and the JSON data is wrapped in a JS function called jsonFlickrFeed. You can find these data source urls in API documentation usually. But many API documentations are often hard to decipher. In this case, this MashupGuide page by Raymond Yee was quite helpful.
  • Line 3-8 are defining the jsonFlickrFeed function that processes the JSON data.

You can think of JSON as a JS object or an associative array of them. Can you also figure out what is going on inside the jsonFlickrFeed function? Let’s go through it line by line.

  • Line 4 creates a variable, container, and sets it to the empty div given the id of the “feed.”
  • Line 5 creates another variable, markup, which will include a link and a title of “fr,” which is an arbitrary name that refers to the JSON data thrown inside the jsonFlickrFeed fucntion.
  • Line 6-8 are a for-loop that goes through every object in the items array and extracts its title and link as well as the image source link and title. The loop also adds the resulting HTML string to the markup variable.
  • Line 9 assigns the content of the markup variable as the value of the HTML content of the variable, container. Since the empty div with the “feed” id was assigned to the variable container, now the feed div has the content of var markup as its HTML content.

So these two JS snippets take an empty div like this:

<div id="feed"></div>

Then they dynamically generate the content inside with the source data from Flickr following some minimal presentation specified in the JS itself. Below is the dynamically generated content for the feed div. The result like this.

<div id="feed">
<h1>
<a href="http://www.flickr.com/photos/tags/cil2009/">Recent Uploads tagged cil2009</a>
</h1>
<a href="http://www.flickr.com/photos/matthew_francis/3458100856/" title="Waiting at Vienna metro (cropped)">
<img alt="Waiting at Vienna metro (cropped)" src="http://farm4.staticflickr.com/3608/3458100856_d01b26cf1b_m.jpg">
</a>
<a href="http://www.flickr.com/photos/libraryman/3448484629/" title="Laptop right before CIL2009 session">
<img alt="Laptop right before CIL2009 session" src="http://farm4.staticflickr.com/3389/3448484629_9874f4ab92_m.jpg">
</a>
<a href="http://www.flickr.com/photos/christajoy42/4814625142/" title="Computers in Libraries 2009">
<img alt="Computers in Libraries 2009" src="http://farm5.staticflickr.com/4082/4814625142_f9d9f90118_m.jpg">
</a>
<a href="http://www.flickr.com/photos/librarianinblack/3613111168/" title="David Lee King">
<img alt="David Lee King" src="http://farm4.staticflickr.com/3354/3613111168_02299f2b53_m.jpg">
</a>
<a href="http://www.flickr.com/photos/librarianinblack/3613111084/" title="Aaron Schmidt">
<img alt="Aaron Schmidt" src="http://farm4.staticflickr.com/3331/3613111084_b5ba9e70bd_m.jpg">
</a>
<a href="http://www.flickr.com/photos/librarianinblack/3612296027/" block"="" libraries"="" in="" computers="" title="The Kids on the ">
<img block"="" libraries"="" in="" computers="" alt="The Kids on the " src="http://farm3.staticflickr.com/2426/3612296027_6f4043077d_m.jpg">
</a>
<a href="http://www.flickr.com/photos/pegasuslibrarian/3460426841/" title="Dave and Greg look down at CarpetCon">
<img alt="Dave and Greg look down at CarpetCon" src="http://farm4.staticflickr.com/3576/3460426841_ef2e57ab49_m.jpg">
</a>
<a href="http://www.flickr.com/photos/pegasuslibrarian/3460425549/" title="Jason and Krista at CarpetCon">
<img alt="Jason and Krista at CarpetCon" src="http://farm4.staticflickr.com/3600/3460425549_55443c5ddb_m.jpg">
</a>
<a href="http://www.flickr.com/photos/pegasuslibrarian/3460422979/" title="Lunch with Dave, Laura, and Matt">
<img alt="Lunch with Dave, Laura, and Matt" src="http://farm4.staticflickr.com/3530/3460422979_96c020a440_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3436564507/" title="IMG_0532">
<img alt="IMG_0532" src="http://farm4.staticflickr.com/3556/3436564507_551c7c5c0d_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3436566975/" title="IMG_0529">
<img alt="IMG_0529" src="http://farm4.staticflickr.com/3328/3436566975_c8bfe9b081_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3436556645/" title="IMG_0518">
<img alt="IMG_0518" src="http://farm4.staticflickr.com/3579/3436556645_9b01df7f93_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3436569429/" title="IMG_0530">
<img alt="IMG_0530" src="http://farm4.staticflickr.com/3371/3436569429_92d0797719_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3436558817/" title="IMG_0524">
<img alt="IMG_0524" src="http://farm4.staticflickr.com/3331/3436558817_3ff88a60be_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3437361826/" title="IMG_0521">
<img alt="IMG_0521" src="http://farm4.staticflickr.com/3371/3437361826_29a38e0609_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3437356988/" title="IMG_0516">
<img alt="IMG_0516" src="http://farm4.staticflickr.com/3298/3437356988_5aaa94452c_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3437369906/" title="IMG_0528">
<img alt="IMG_0528" src="http://farm4.staticflickr.com/3315/3437369906_01015ce018_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3436560613/" title="IMG_0526">
<img alt="IMG_0526" src="http://farm4.staticflickr.com/3579/3436560613_98775afc79_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3437359398/" title="IMG_0517">
<img alt="IMG_0517" src="http://farm4.staticflickr.com/3131/3437359398_7e339cf161_m.jpg">
</a>
<a href="http://www.flickr.com/photos/jezmynne/3436535739/" title="IMG_0506">
<img alt="IMG_0506" src="http://farm4.staticflickr.com/3646/3436535739_c164062d6b_m.jpg">
</a>
</div>

Strictly speaking, Flickr is returning data in JSONP rather than JSON here. You will see what JSONP means in a little bit. But for now, don’t worry about that distinction. What is cool is that you can grab the data from a third party like Flickr and then you can remix and represent them in your own page.

Warm-up 2: Doing the same with JQuery using $.getJSON()

Since I had figured out how to display data from Flickr using Javascript (thanks to Jason’s code example), the next I wanted to try was to do the same with JQuery. After some googling, I discovered that there is a convenient JQeury method called $.getJSON(). The official JQuery page on this $.getJSON() method includes not only the explanation about JSONP (which allows you to load the data from the domain other than yours in your browser and manipulate it unlike JSON which will be restricted by the same origin policy) but also the JQuery example of processing the same Flickr JSONP data. This is the example from the JQuery website.

$.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?",
  {
    tags: "mount rainier",
    tagmode: "any",
    format: "json"
  },
  function(data) {
    $.each(data.items, function(i,item){
      $("<img/>").attr("src", item.media.m).appendTo("#images");
      if ( i == 3 ) return false;
    });
  });

As you can see in the first line, the data feed urls for JSONP response have a part similar to &jasoncallback=? at the end. The function name can vary and the API documentation of a data provider provides that bit of information. Let’s go through the codes line by line:

  • Line 1-6 requests and takes in the data feed from the speicified URL in JSONP format.
  • Once the data is received and ready, the script invokes the anonymous function from line 7-11. This function makes use of the JQuery method $.each().
  • For each of data.items, the anonymous function applies another anonymous function from line 9-10.
  • Line 9 creates an image tag – $(“<img/>”), attaches each item’s media.m element as the source attribute to the image tag – .attr(“src”, item.media.m), and lastly appends the resulting string to the empty div with the id of “images” – .appendTo(“#images”).
  • Line 10 makes sure that no more than 4 items in data.items is processed.

You can see the entire HTML page codes in the JQuery website’s $.getJSON() page.

Your Turn: Try out an API other than Flickr

So far we have looked through two examples. Not too bad, right? To keep the post at a reasonable length, I will get to the little bit of code that I wrote in the next post. This means that you can try the same and we can compare the result next time. Now here is the challenge. Both examples we saw used the Flickr API. Could you write code for a different API provider that does the same thing? Remember that you have to pick a data provider that offers feeds in JSONP if you want to avoid dealing with the same origin policy.

Here are a few providers you might want to check out. They all offer their data feeds in JSONP.

First, find out what data URLs you can use to get JSONP responses. Then write several lines of codes in JS and JQuery to process and display the data in the way you like in your own webpage. You may end up with some googling and research while you are at it.

Here are a few tips that will help you along the way:

  • Verify the data feed URL to see if you are getting the right JSONP responses. Just type the source url into the browser window and see if you get something like this.
  • Get the Firebug for debugging if you don’t already have it.
  • Use the Firebug’s NET panel to see if you are receiving the data OK.
  • Use the Console panel for debugging. The part of data that you want to pick up may be in several levels deep. So it is useful to know if you are getting the right item first before trying to manipulate it.

Happy Coding! See the following screenshots for the Firebug NET panel and Console panel. (Click the images to see the bigger and clearer version.) Don’t forget to share your completed project in the comments section as well as any questions, comments, advice, suggestions!

Net panel in Firebug

 

 

Console panel in Firebug