During the next couple of days I will be releasing a new version compatible with jQuery 1.4 – It will be a good way to get back to some Javascript hacking after many months with just Ruby in my head

Stay tuned!

Update:

So it just took me an hour to do the update to 1.4 — seems like jQuery.queue() is behaving a little different.

Since the plugins site for 1.4 is still to be released, for now you can grab the code from GitHub: http://github.com/lucianopanaro/jQuery-FxQueues/tree/jQuery1.4

Nothing crazy, but hopefully I’m saving you a headache .

So if you are using jQuery 1.3.1, you should be using FxQueues 2.0.3, otherwise you can stick to 2.0.2, as only internal changes have been done and there are no new features.

The new improvement is that now you can store a selection automatically:

// Will store in cache $("#sidebarNav") with #sidebarNav key
$$("#sidebarNav");

This will let you avoid doing $(“#menu”).cache(“menu”), which is a bit redundant. Now by doing $$(“#menu”) you will be able to store it in the cache and retrieve it automatically. There is also a reload option that you can pass to that call in order to, well, reload the the cached object with that selection:

// Will reload #sidebarNav with $("#sidebarNav")
$$("#sidebarNav", true);

You can grab the new version of the Object Cache plugin here.

After reading this comment, and going through the code, I decided to implement the time-based switching functionality and also clean up the code a little bit (check it out here).

The additions made (along with some code cleaning) were:

• Append a simple div that will shrink while the picture is shown and reinitialized when the picture is switched.
• Add a setInterval call that will do the picture switching (and the new div’s animation).

Update 01/12: I added some fixes to the code

• Use the image’s load event to calculate each individual width. When all images are loaded, then the carousel is initiated.
• The animate_timer function now stops all animations on the timer div before reinitializing the animation

Update 01/27: Even more fixes

• Work with cases were images are already in cache and load event is fired before we attach to it.
• Fixed the way the news animation was calculated.
• Added 2 more news to help test it better.

So here’s the new javascript that will do this:

$(function() {
    var carousel   = $('#news_carousel');
    var news       = carousel.find('ul.news');
    var controls   = null; // Will hold the ul with the controls
    var timer      = null; // Will hold the timer div
    var wait       = 5000; // Milliseconds to wait for auto-switching
    var widths     = [];   // Will hold the widths of each image
    var items_size = news.find('li').length;
    var initialized = false;

    if (!items_size) { return; }

    // Controls html to append
    var controls_str = '<ul class="controls">';
    for ( var i = 1; i &lt;= items_size; i++) {
       controls_str += '<li><a href="#">' + i + '</a></li>';
    }
    controls_str += '</ul>';

    // Cache the controls list
    controls = carousel.append(controls_str).find('ul.controls');

    // Make the first button in controls active
    controls.find('li:first a').addClass('active');

    // Hook to the controls' click events
    controls.find('li a').click(function(event) {
      move_news( $(this) );
      return false;
    });

    // Append the timer and cache it
    timer = carousel.append('<div class="timer"></div>').find('div.timer');

    // Store each item's width and calculate the total width
    news.find('li img')
        .each(function(i, e) {
            widths[i] = $(e).width();
            if ( all_images_loaded() ) { init_carousel(); }
        })
        .load(function(e) {
            var i = news.find('li img').index(this);
            widths[i] = $(this).width();
            if ( all_images_loaded() ) { init_carousel(); }
        });


    function all_images_loaded() {
      return (items_size == widths.length) &amp;&amp; (jQuery.inArray(0, widths)  1 ) {
        return false;
      }

      var current_active = controls.find('li a.active');

      if (new_active == 'next') {
        var next = current_active.parent().next().find('a');

        if ( !next.length ) { next = controls.find('li:first a'); }

        new_active = next;
      }

      var current_index = parseInt(current_active.text(), 10) - 1;
      var new_index     = parseInt(new_active.text(), 10) - 1;
      var move_to       = new_index - current_index;


      if (!move_to) { return false; }

      var direction = (move_to &gt; 0)? '-=': '+=';

      var move   = 0;
      var bottom = Math.min(current_index, new_index);
      var top    = Math.max(current_index, new_index);

      while (bottom &lt; top) {
        move += widths[bottom];
        bottom++;
      }

      news.animate({marginLeft: direction + move }, 500);
      new_active.addClass('active');
      current_active.removeClass('active');
    }

    function animate_timer() {
      timer.stop().css({width: '100px'}).animate({width: '1px'}, wait);
    }

    // Initializer, called when all images are loaded
    function init_carousel() {
      if (initialized) { return false; }

      // Set the news ul total width
      var width = 0;
      for( var i = 0; i &lt; widths.length; i++) { width += widths[i]; }
      news.width(width);

      // Make the news change every X seconds
      setInterval(function() { move_news('next'); animate_timer(); }, wait);
      animate_timer();

      initialized = true;
    }
});

Its objective is to let you store a jQuery object with a simple key in a global cache,
so that you can access the same object easily, without having to write the same selection, filtering or traversing code (i.e: $(“#main > p”) or $(“#main”).children(“.selected”).eq(0)).

Here is how it works:

// Store in cache - Returns current object
$("#mainNav").cache("main_navigation");

// Retrieve from cache - Returns cached object
$$("main_navigation"); // or jQueryCache("main_navigation");

// Remove from cache
$$.remove("main_navigation");

// Clear Cache
$$.clear();

// Load jQueryCache with noConflict to avoid overriding window.$$
$$.noConflict();

There is a lot of room for improvement, which will be done depending on the feedback I get, so feel free to contact me with any ideas or corrections you might come up with.

You can get the Jquery Object Cache plugin here.

“Rack provides a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.”

So you can think of Rack as a “frameworks framework“. Merb and other ruby frameworks already support Rack, which means that they can share the middleware described above.

Creating a Rack Middleware

So let’s say you want your application (built on Rails, Merb, Ramaze or even Rack) to intercept any request for javascript files so that you can first minify them. Below is the sample code for achieving this with a Rack Middleware:

(You can checkout this code, its spec and example from http://github.com/lucianopanaro/rack-javascript-minifier. The javascript minifier is a port from Douglas Crockford’s library done by Ryan Grove.)

  class JavascriptMinifier
    F = ::File

    def initialize(app, path)
      @app = app
      @root = F.expand_path(path)
      raise "Provided path #{@root} does not exist" unless F.directory?(@root)
    end

    def call(env)
      path = F.join(@root, Utils.unescape(env["PATH_INFO"]))

      unless path.match(/.*\/(\w+\.js)$/) and F.file?(path)
        return @app.call(env)
      end

      if env["PATH_INFO"].include?("..") or !F.readable?(path)
        body = "Forbidden\n"
        size = body.respond_to?(:bytesize) ? body.bytesize : body.size
        return [403, {"Content-Type" => "text/plain","Content-Length" => size.to_s}, [body]]
      end

      last_modified = F.mtime(path)
      min_path = F.join(@root, "m_#{last_modified.to_i}_#{F.basename(path)}")

      unless F.file?(min_path)
        F.open(path, "r") { |file|
          F.open(min_path, "w") { |f| f.puts JSMin.minify(file) }
        }
      end

      [200, {
             "Last-Modified"  => F.mtime(min_path).httpdate,
             "Content-Type"   => "text/javascript",
             "Content-Length" => F.size(min_path).to_s
            }, F.new(min_path, "r")]
    end
  end

Rack Middleware’s interface is dead simple. As Marc-André Cournoyer points out: “It must have a call method and receive a Rack app as the first argument of new”.

So here, when we initialize the JavascriptMinifier, we pass the root path where the javascript files are placed. Every time it gets called, the middleware first checks if the request is for a javascript file. If it’s not, it passes it to the application. If the request is for a javascript in a parent directory, then we return a forbidden (403) page. Finally, if the request passes these filters, the middleware creates a minified version of the javascript file and returns it.

Running your application with middleware

This is also really simple using Rack::Builder:

“Rack::Builder implements a small DSL to iteratively construct Rack applications. use adds a middleware to the stack, run dispatches to an application.”

So here is an example of a rackup file that you can use to startup your application with some middleware:

   use Rack::CommonLogger
   use Rack::ShowExceptions
   use JavascriptMinifier, "./"
   run Rack::Lobster.new

Testing and Spec’ing helpers

Rack provides two helpers that will be of great use for testing your application: Rack::MockRequest and Rack::MockResponse, so you have no excuses to test your Rack Middleware and do some TDD/BDD!

Where to go from here

To learn how to develop your own Rack Middleware, your best resource will be Rack sources. You will learn a lot of Rack (and Ruby in general) by reading the code and specs they provide: URLMap, CommonLogger, File. There also is a group where you can ask your questions too.

So enjoy your trip with Rack Middleware and feel free to comment your thoughts and questions!

So first let’s take a look at what we want to build.

Now, I know that there are a few plugins out there for jQuery that probably can do this, but the point of this post is to show how simple it is to create something like this with a few lines of jQuery and CSS.

Let’s begin by defining how we will organize the content. Being a list of news, we can either use an ordered or an unordered list.

<div id="news_carousel">
  <ul class="news">
    <li>
      <img src="" alt="" />
      <strong><a href="#">Title</a></strong>
      <span>Description</span>
    </li>
  </ul>
</div>

Now that we have our content, we have to style it. The keys here are to:

• Align the list elements one next to the other.
• Make #news_carousel just show one list element at a time
• Use relative and absolute positioning to show the titles and descriptions over each image

Here’s the CSS used in the sample with some comments:

 #news_carousel {
     width: 444px;
     height: 333px;
     margin: 0;
     padding: 0;
     overflow: hidden;  /* this will make only show 1 li */
     position: relative;
  }
  #news_carousel ul.news {
    list-style-type: none;
    margin: 0;
    padding: 0;
    position: relative;
  }
  #news_carousel ul li {
    margin: 0;
    padding: 0;
    position: relative; /* so that we can do absolute positioning of the paragraph inside of it */
    float: left; /* align one next to the other */
  }
  #news_carousel ul.news li p {
    position: absolute;
    bottom: 10px;
    left: 0;
    margin: 5px;
  }
  #news_carousel ul.news li p strong {
    display: block;
    padding: 5px;
    margin: 0;
    font-size: 20px;
    background: #444;
  }
  #news_carousel ul.news li p span {
    padding: 2px 5px;
    color: #000;
    background: #fff;
  }
  #news_carousel ul.controls {
    position: absolute;
    top: 0px; right: 20px;
    list-style-type: none;
  }
  #news_carousel ul.controls li a {
    float: left;
    font-size: 15px;
    margin: 5px;
    padding: 2px 7px;
    background: #000;
    text-decoration: none;
    outline: none;
  }
  #news_carousel ul.controls li a.active {
    border: 2px solid #ccc;
  }

The Javascript code is pretty self-explanatory:

var news_carousel = function() {
    var items_size = $('#news_carousel ul li').length;

    if (items_size == 0) return;

    // Calculate the total width and set that value to the ul.news width
    // Store each item width
    var width = 0;
    var widths = [];
    $('#news_carousel ul.news li img').each(function(i, e) {
      widths[i] = $(e).width();
      width += widths[i];
    });

    $("#news_carousel ul.news").width(width);

    // Append the controls
    controls = '<ul class="controls"><li><a class="active" href="#">1</a>';
    for ( var i = 2; i &lt;= items_size; i++) {
       controls += '</li><li><a href="#">' + i + '</a></li>';
    }
    controls += '</ul>';
    $('#news_carousel').append(controls);

    $('#news_carousel ul.controls li a').click(function(event) {
      // if the ul is already moving, then do nothing
      if ($("#news_carousel ul.news:animated").length &gt; 0) return false;

      var clicked_item = $(event.target);
      var current_active = $("#news_carousel ul.controls li a.active");
      var current_index = parseInt(current_active.text());
      var new_index = parseInt(clicked_item.text());
      var move = new_index - current_index; // get how many items it should be moved

      if (move != 0) {
        direction = (move &gt; 0)? "-=": "+=";
        $('#news_carousel ul.news').animate({marginLeft: direction + widths[new_index-1] }, 300);
        clicked_item.addClass("active");
        current_active.removeClass("active");
      }

      return false;
    });
  }();

And that’s it! Around 100 lines of code and you have your own home-made news carousel. Hope you found it useful!

(Pictures taken from: http://www.flickr.com/photos/christing/268490607/ and http://www.flickr.com/photos/11717181@N02/1170861540/.)

RSpec Story Runner is being replaced by Cucumber for RSpec 1.1.5, but as mentioned here, if you are about to start you should go with Cucumber. Here are the instructions for installing RoR support.

• RSpec’s site (there are a few examples for Rails controllers, models, views and helpers)
• RSpec on Github
• Cucumber
• Webrat
• David Chelimsky’s (RSpec’s creator) blog
• Andrzej Krzywda’s blog
  • BDD examples with user stories and Webrat
  • Story Driven Development
  • TDD with Rails
• RSpec and Restful Authentication
• RSpec plain text story runner on a fresh rails app
• Story writing is fun
• Some RSpec useful links
• RSpec, it should behave like
• Understanding RSpec stories, a tutorial
• NetBeans: Screencast on RSpec support

Hope you find it useful!

When I launched this blog a few months ago I promised myself I would post at least weekly. Well, it is pretty obvious that I haven’t. Even more, I was just able to do a few posts commenting on some news I found interesting.

So the inmediate question that comes up is simply “why?” . Well, there are many reasons why:

• Study comes first.
• Work comes second (well, it comes first sometimes).
• I couldn’t find time to write (a sort of corollary of the first two) anything I liked.
• I hated the template I had.

From these bullets, there is one that can be (sort of) easily fixed. Creating a new appealing template that would make me want to post every week can’t be that hard, right? Well, it is, especially if you are a designer-wannabe. It took me a long time to come up with a template that I liked, but I am pretty glad with the result.

In the meantime, I came across a plugin from John Resig with similar functionality. Since it’s core implementation was far better than mine, I updated the jQuery FxQueues Plugin to a 2.0 version, by merging John’s and my code (I also created a new example page and some unit tests).

So now that I have a template that I like there is one thing less preventing me from writing new posts. I have a few ideas for some posts and hopefully you will be able to read them soon.

Hope you like this new template as I do!