ajax 不错的应用

<script type="text/javascript" language="javascript">

var http_request = false;

function makeRequest(url) {

http_request = false;

if (window.XMLHttpRequest) { // Mozilla, Safari,...
            http_request = new XMLHttpRequest();
            if (http_request.overrideMimeType) {
                http_request.overrideMimeType('text/xml');
            }
        } else if (window.ActiveXObject) { // IE
            try {
                http_request = new ActiveXObject("Msxml2.XMLHTTP");
            } catch (e) {
                try {
                    http_request = new ActiveXObject("Microsoft.XMLHTTP");
                } catch (e) {}
            }
        }

if (!http_request) {
            alert('Giving up :( Cannot create an XMLHTTP instance');
            return false;
        }
        http_request.onreadystatechange = alertContents;
        http_request.open('GET', url, true);
        http_request.send(null);

}

function alertContents() {

if (http_request.readyState == 4) {
            if (http_request.status == 200) {
                alert(http_request.responseText);
            } else {
                alert('There was a problem with the request.');
            }
        }

}
</script>
<span
    style="cursor: pointer; text-decoration: underline"
    onclick="makeRequest('test.html')">
        Make a request
</span>

var http_request = false;

function makeRequest(url) {

http_request = false;

if (window.XMLHttpRequest) { // Mozilla, Safari,...
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType) {
http_request.overrideMimeType('text/xml');
}
} else if (window.ActiveXObject) { // IE
try {
http_request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}

if (!http_request) {
alert('Giving up :( Cannot create an XMLHTTP instance');
return false;
}
http_request.onreadystatechange = alertContents;
http_request.open('GET', url, true);
http_request.send(null);

}

function alertContents() {

if (http_request.readyState == 4) {
if (http_request.status == 200) {
var xmldoc = http_request.responseXML;
var root_node = xmldoc.getElementsByTagName('root').item(0);
alert(root_node.firstChild.data);
} else {
alert('There was a problem with the request.');
}
}

}

Make a request

[Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]