PHP development basic tutorial AJAX RSS Reader

AJAX RSS Reader

RSS Reader is used to read RSS Feeds.

Example:

In the following example, we will demonstrate an RSS reader, through which the content from RSS is read without refreshing the web page. Loading:

This example includes three parts

• HTML form page

• PHP file

• XML file

---

##HTML form page

When the user selects an RSS-feed in the drop-down list above, a function named "showRSS()" is executed. This function is triggered by the "onchange" event:

See 1.php for the source code

     
  
   选择一个 RSS-feed: 读取 RSS 数据  
 
 
RSS-feed 数据列表...
  

The above HTML page contains a simple HTML form with a drop-down list box.

The form works like this:

• When the user selects an option in the drop-down box, an event is triggered

• When the event is triggered, execute the showRSS() function

• Below the form is a
  named "rssOutput". It is used as a placeholder for the data returned by the showRSS() function.

The showRSS() function will perform the following steps:

• Check whether an RSS-feed is selected

• Create an XMLHttpRequest object

• Create a function that is executed when the server response is ready

• Send a request to a file on the server

• Please note the parameter (q) added to the end of the URL (containing the contents of the drop-down list)

---

PHP file

The server page called above through JavaScript is a PHP file named "2.php":

See 2.php

load($xml); // 从 "" 中读取元素 $channel=$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; // 输出 "" 中的元素 echo("
" . $channel_title . ""); echo("
"); echo($channel_desc . "
"); // 输出 "" 中的元素 $x=$xmlDoc->getElementsByTagName('item'); for ($i=0; $i<=1; $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 ("
" . $item_title . ""); echo ("
"); echo ($item_desc . "
"); } ?>

for the source code When a request for an RSS feed is sent from JavaScript to a PHP file, what happens is:

• Check which RSS feed is selected

• Create a new one XML DOM object

• Load RSS document in xml variable

• Extract and output elements from channel element

• Extract and output elements from item elements

---

XML file

    //m.sbmmt.com 学的不仅技术，更新梦想！！   //m.sbmmt.com/rss/rss-tutorial.html 通过使用 RSS，您可以有选择地浏览您感兴趣的以及与您的工作相关的新闻    //m.sbmmt.com/xml/xml-tutorial.html XML 指可扩展标记语言（eXtensible Markup Language）   

---

Learning experience

This example mainly includes the following knowledge points:

• Form basics

• onkeyup event: when the keyboard key is pressed Occurs when released

• Function call, function value transfer

• Creation of AJAX XMLHttpRequest object, function executed when the server responds, and File sending request on the server: see 1-5 for learning experience

• HTML DOM getElementById() method: Returns a reference to the first object with the specified ID

XML related knowledge

• Create an XML DOM object

• Load the XML file into a new XML DOM object

• Get the object with a specific tag name: getElementsByTagName ()

• Returns the first child node of the element: HTML DOM item() method