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How to Build a Super Duper News Scroller

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This week, we'll learn how to combine PHP, SimplePie, and jQuery to build a simple news scroller widget for your website. It's much easier than you might think; so let's begin.

Note that I modified the code slightly after recording this screencast. Don't worry, they're just minor changes; but as with anything, you should continuously refactor your code.

Final Product

Final NewsScroll Plugin

(function($) {

$.fn.newsScroll = function(options) {
    
    return this.each(function() {   
      
        var
          $this = $(this), 
          
          defaults = {
            speed: 400, 
            delay: 3000, 
            list_item_height: $this.children('li').outerHeight() 
         },
         
          settings = $.extend({}, defaults, options); 
         
      setInterval(function() {
            $this.children('li:first')
                    .animate({ 
                        marginTop : '-' + settings.list_item_height, 
                       opacity: 'hide' },
                       
                       settings.speed,

                       function() {
                            $this
                              .children('li:first')
                              .appendTo($this)
                              .css('marginTop', 0) 
                              .fadeIn(300); 
                      }
                  ); // end animate
      }, settings.delay); // end setInterval
    });
}

})(jQuery);

With Commenting

// Create a self-invoking anonymous function. That way, 
// we're free to use the jQuery dollar symbol anywhere within.
(function($) {

// We name our plugin "newscroll". When creating our function, 
// we'll allow the user to pass in a couple of parameters.
$.fn.newsScroll = function(options) {
    
    // For each item in the wrapped set, perform the following. 
    return this.each(function() {   
      
        var
          // Caches this - or the ul widget(s) that was passed in.
          //  Saves time and improves performance.
          $this = $(this), 
          
          // If the user doesn't pass in parameters, we'll use this object. 
          defaults = {
            speed: 400, // How quickly should the items scroll?
            delay: 3000, // How long a rest between transitions?
            list_item_height: $this.children('li').outerHeight() // How tall is each list item? If this parameter isn't passed in, jQuery will grab it.
         },
          // Create a new object that merges the defaults and the 
          // user's "options".  The latter takes precedence.
          settings = $.extend({}, defaults, options);
         
      // This sets an interval that will be called continuously.
      setInterval(function() {
            // Get the very first list item in the wrapped set.
            $this.children('li:first')
                    // Animate it
                    .animate({ 
                        marginTop : '-' + settings.list_item_height, // Shift this first item upwards.
                       opacity: 'hide' }, // Fade the li out.
                       
                       // Over the course of however long is 
                       // passed in. (settings.speed)
                       settings.speed, 
                       
                       // When complete, run a callback function.
                       function() {
                        
                        // Get that first list item again. 
                            $this.children('li:first')
                                 .appendTo($this) // Move it the very bottom of the ul.
                                 
                                 // Reset its margin top back to 0. Otherwise, 
                                 // it will still contain the negative value that we set earlier.
                                 .css('marginTop', 0) 
                                 .fadeIn(300); // Fade in back in.
                      }
                  ); // end animate
      }, settings.delay); // end setInterval
      });
}

})(jQuery);

Final Page

<?php

require 'simplepie.inc';
$feed = new SimplePie('http://net.tutsplus.com/rss');
$feed->handle_content_type();

?>

<!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" />
<link rel="stylesheet" href="style.css" type="text/css" media="screen" charset="utf-8" />
<title>Super Duper News Scroller</title>
</head>

<body>

<div id="container">
    <h1>Super Duper News Scroller: <small>Built With PHP, SimplePie, and jQuery</small</h1>
        
        <ul id="widget">
            <?php foreach($feed->get_items(0, 15) as $item) : ?>
            <li>
                <?php echo $item->get_description(); ?>
                <h4><a href="<?php echo $item->get_permalink(); ?>"><?php echo $item->get_title(); ?></a></h4>
                <p>
                    <?php echo $item->get_date(); ?>
                </p>
            </li>
            <?php endforeach; ?>
        </ul>
</div><!--end container-->

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
<script type="text/javascript" src="jquery.newsScroll.js"></script>

<script type="text/javascript">
    $('#widget').newsScroll({
        speed: 2000,
        delay: 5000
    });
    
    // or just call it like:
    // $('#widget').newsScroll();
</script>

</body>
</html>

That's It

In twenty minutes, we were able to build a nice and simple scroller. You're now free to take the plugin and expand it to your needs. What you have here should be considered the first step. How can you improve upon it?

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