PHP Example – AJAX RSS Reader

PHP Example – AJAX RSS Reader
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An RSS Reader is used to read RSS Feeds.

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 “showRSS()” is executed. The function is triggered by the “onchange” event:

function showRSS(str) {
  if (str.length==0) {
    document.getElementById(“rssOutput”).innerHTML=””;
    return;
  }
  if (window.XMLHttpRequest) {
    // code for IE7+, Firefox, Chrome, Opera, Safari
    xmlhttp=new XMLHttpRequest();
  } else {  // code for IE6, IE5
    xmlhttp=new ActiveXObject(“Microsoft.XMLHTTP”);
  }
  xmlhttp.onreadystatechange=function() {
    if (this.readyState==4 && this.status==200) {
      document.getElementById(“rssOutput”).innerHTML=this.responseText;
    }
  }
  xmlhttp.open(“GET”,”getrss.php?q=”+str,true);
  xmlhttp.send();
}

<select onchange="showRSS(this.value)">
Select an RSS-feed:
Google News
NBC News

The showRSS() 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”:

<?php
//get the q parameter from URL
$q=$_GET[“q”];

//find out which feed was selected
if($q==”Google”) {
  $xml=(“http://news.google.com/news?ned=us&topic=h&output=rss“);
} elseif($q==”NBC”) {
  $xml=(“http://rss.msnbc.msn.com/id/3032091/device/rss/rss.xml“);
}

$xmlDoc = new DOMDocument();
$xmlDoc->load($xml);

//get elements from “”
$channel=$xmlDoc->getElementsByTagName(‘channel’)->item(0);
$channel_title = $channel->getElementsByTagName(‘title’)
->item(0)->childNodes->item(0)->nodeValue;
$channel_link = $channel->getElementsByTagName(‘link’)
->item(0)->childNodes->item(0)->nodeValue;
$channel_desc = $channel->getElementsByTagName(‘description’)
->item(0)->childNodes->item(0)->nodeValue;

//output elements from “”
echo(“

<a href='" . $channel_link
  . “‘>” . $channel_title . ““);
echo(“
“);
echo($channel_desc . “

“);

//get and output “” elements
$x=$xmlDoc->getElementsByTagName(‘item’);
for ($i=0; $i<=2; $i++) {
  $item_title=$x->item($i)->getElementsByTagName(‘title’)
  ->item(0)->childNodes->item(0)->nodeValue;
  $item_link=$x->item($i)->getElementsByTagName(‘link’)
  ->item(0)->childNodes->item(0)->nodeValue;
  $item_desc=$x->item($i)->getElementsByTagName(‘description’)
  ->item(0)->childNodes->item(0)->nodeValue;
  echo (“

<a href='" . $item_link
  . “‘>” . $item_title . ““);
  echo (“
“);
  echo ($item_desc . “

“);
}
?>
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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