May 11, 2021 PHP
RSS is a format for describing and synchronizing website content and is currently the most widely used XML application.
RSS provides a technology platform for rapid information dissemination, making everyone a potential information provider.
RSS readers are used to read RSS feeds.
In the following example, we'll demonstrate an RSS reader through which content from RSS is loaded without refreshing the page:
When a user selects an RSS-feed in the drop-down list above, a function named "showRSS()" is executed. The function is triggered by the "onchange" event:
<html>
<head>
<script>
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 (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("rssOutput").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","getrss.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<form>
<select onchange="showRSS(this.value)">
<option value="">Select an RSS-feed:</option>
<option value="Google">Google News</option>
<option value="MSNBC">MSNBC News</option>
</select>
</form>
<br>
<div id="rssOutput">RSS-feed will be listed here...</div>
</body>
</html>
The showRSS() function performs the following steps:
The server page called by JavaScript above is a PHP file .php "getrss":
<?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=="MSNBC")
{
$xml=("http://rss.msnbc.msn.com/id/3032091/device/rss/rss.xml");
}
$xmlDoc = new DOMDocument();
$xmlDoc->load($xml);
//get elements from "<channel>"
$channel=$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 "<channel>"
echo("<p><a href='" . $channel_link
. "'>" . $channel_title . "</a>");
echo("<br>");
echo($channel_desc . "</p>");
//get and output "<item>" 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 ("<p><a href='" . $item_link
. "'>" . $item_title . "</a>");
echo ("<br>");
echo ($item_desc . "</p>");
}
?>
When an RSS feed request is sent from JavaScript to a PHP file, it occurs: