Tuesday, 28 May 2013
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PHP Example - AJAX RSS Reader


The following example will demonstrate an RSS reader, where the RSS-feed is loaded into a webpage without reloading:

RSS-feed will be listed here...

Example Explained - The HTML Page

When a user selects an RSS-feed in the dropdown list above, a function called "showResult()" is executed. The function is triggered by the "onchange" event:
function showRSS(str)
if (str.length==0)
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  if (xmlhttp.readyState==4 && xmlhttp.status==200)

<select onchange="showRSS(this.value)">
<option value="">Select an RSS-feed:</option>
<option value="Google">Google News</option>
<option value="MSNBC">MSNBC News</option>
<div id="rssOutput">RSS-feed will be listed here...</div>
The showResult() function does the following:
  • Check if an RSS-feed is selected
  • Create an XMLHttpRequest object
  • Create the function to be executed when the server response is ready
  • Send the request off to a file on the server
  • Notice that a parameter (q) is added to the URL (with the content of the dropdown list)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "getrss.php":
//get the q parameter from URL

//find out which feed was selected

$xmlDoc = new DOMDocument();

//get elements from "<channel>"
$channel_title = $channel->getElementsByTagName('title')
$channel_link = $channel->getElementsByTagName('link')
$channel_desc = $channel->getElementsByTagName('description')

//output elements from "<channel>"
echo("<p><a href='" . $channel_link
  . "'>" . $channel_title . "</a>");
echo($channel_desc . "</p>");

//get and output "<item>" elements
for ($i=0; $i<=2; $i++)

  echo ("<p><a href='" . $item_link
  . "'>" . $item_title . "</a>");
  echo ("<br>");
  echo ($item_desc . "</p>");
When a request for an RSS feed is sent from the JavaScript, the following happens:
  • Check which feed was selected
  • Create a new XML DOM object
  • Load the RSS document in the xml variable
  • Extract and output elements from the channel element
  • Extract and output elements from the item elements

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