AJAX XML
PHP Example - AJAX and XML
AJAX can be used to communicate interactively with XML files.
AJAX XML Example
The following example will demonstrate how a web page reads information from an XML file through AJAX:
Example
Example explanation - HTML page
When the user is in When a CD is selected in the drop-down list above, a function named "showCD()" will be executed. This function is triggered by the "onchange" event:
<html>
<head>
<script>
function showCD(str)
{
if (str=="")
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{
// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行
xmlhttp=new XMLHttpRequest();
}
else
{
// IE6, IE5 浏览器执行
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","getcd.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<form>
Select a CD:
<select name="cds" onchange="showCD(this.value)">
<option value="">Select a CD:</option>
<option value="Bob Dylan">Bob Dylan</option>
<option value="Bonnie Tyler">Bonnie Tyler</option>
<option value="Dolly Parton">Dolly Parton</option>
</select>
</form>
<div id="txtHint"><b>CD info will be listed here...</b></div>
</body>
</html>showCD() function performs the following steps:
Check Whether a CD is selected
Create an XMLHttpRequest object
Create a function that executes 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 (contains the contents of the drop-down list)
PHP file
The server page called above through JavaScript is a PHP file named "getcd.php".
The PHP script loads the XML document, "cd_catalog.xml", runs the query against the XML file, and returns the results in HTML:
<?php
$q=$_GET["q"];
$xmlDoc = new DOMDocument();
$xmlDoc->load("cd_catalog.xml");
$x=$xmlDoc->getElementsByTagName('ARTIST');
for ($i=0; $i<=$x->length-1; $i++)
{
// 处理元素节点
if ($x->item($i)->nodeType==1)
{
if ($x->item($i)->childNodes->item(0)->nodeValue == $q)
{
$y=($x->item($i)->parentNode);
}
}
}
$cd=($y->childNodes);
for ($i=0;$i<$cd->length;$i++)
{
// 处理元素节点
if ($cd->item($i)->nodeType==1)
{
echo("<b>" . $cd->item($i)->nodeName . ":</b> ");
echo($cd->item($i)->childNodes->item(0)->nodeValue);
echo("<br>");
}
}
?>When a CD query is sent from JavaScript to a PHP page, what happens is:
PHP creates an XML DOM object
Finds all <artist> elements Names matching the data passed by JavaScript
Output the album information and send back the "txtHint" placeholder
Related Video Tutorial Recommendation: "AJAX Tutorial"//m.sbmmt.com/course/list/25.html
