retrive XML in ajax way: xmlhttprequest


Following codes is the minimum 4 steps for XMLHttpRequest.



<script language="javascript">



////////////////// initial xmlhttprequest ///////////////////////////

// 1. new XMLHttpRequest()

if (window.XMLHttpRequest) {

req = new XMLHttpRequest();

}

else{

try {

req = new ActiveXObject("Msxml2.XMLHTTP");

} catch (e) {

alert('Old Microsoft.XMLHTTP activexobject before IE 5.5');

try {

req = new ActiveXObject("Microsoft.XMLHTTP");

} catch (e) {}

}

}





////////////////// configure and get xmlhttprequest ///////////////////////////

try{// this try/catch is only for firefox: if you installed firebug,disable it.

netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");

//netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");

}catch (e){}

// 2. request.open()

try{

//req.open("GET", "http://crosszheng.spaces.live.com/feed.rss", true);

req.open("GET", "feed.rss", true);

//alert('get successfully');

}

catch(e){

alert(e.toString());

}

// 3. define request.onreadystatechange function, which is a event handler.

req.onreadystatechange = function() {

try

{

if((req.readyState == 4) && (req.status == 200))

{

try{

xmlobject = (new DOMParser()).parseFromString(req.responseText, "text/xml");

}catch(e){

xmlobject=new ActiveXObject("Microsoft.XMLDOM");

xmlobject.async="false";

xmlobject.loadXML(req.responseText);

}

// get a reference to the root-element "rss"

var root = xmlobject.getElementsByTagName('rss')[0];

// get reference to "channel" element

var channels = root.getElementsByTagName("channel");

// now get all "item" tags in the channel

var items = channels[0].getElementsByTagName("item");

// in the "item" we have a description, so get that

var descriptions = items[0].getElementsByTagName("description");

var desc = descriptions[0].firstChild.nodeValue;

document.write(desc);

document.close();

}

}

catch(e){

alert(e.toString());

}

}

// 4. request.send(null)

req.send(null);



</script>





more details on:http://developer.apple.com/internet/webcontent/xmlhttpreq.html