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SCRIPT5: Access is denied for IE while requesting JSON data

I want to retrieve json data using ajax request in javascript. SO i wrote a reusable code like the following.
function ajaxRequest() {
var req;
this.ajax = function(params, url) {
if (window.XMLHttpRequest) { // code for IE7+, Firefox, Chrome, Opera, Safari
req = new XMLHttpRequest();
} else { // code for IE6, IE5
req = new ActiveXObject("Microsoft.XMLHTTP");
}
req.open("POST", url, true);
req.setRequestHeader('Access-Control-Allow-Headers', '*');
req.setRequestHeader('Content-Type', 'application/json; charset=utf-8');
req.onreadystatechange = function() {
console.log('state\t' + req.readyState);
return req.responseText;
};
req.send(params);
}
}
How to retrieve data without changing Settings->Internet Options->Security->Custom Level and change security settings under "Miscellaneous" set "Access data sources across domains" to Enable.
For rest all browsers except IE its not working.

My IP gets blocked for odd reasons by my server each time i do ajax continuous update

Everytme when i call ajax and i use timeout to repeat the ajax function, after a few minutes, i can't have access to my website, it;s like my IP address gets blocked from my server, by the way i am using 000webhost for hosting my server. The code is below .Can someone assist me and tell me what i can do solve this problem without telling me to use websockets/comets, i want to use AJAX for very frequent update maybe up to 10 seconds. Not a most but it will be great if someone can show solutions without the use use of JQuery Thank you.
function display_message(user,id){
var xhr;
if (window.XMLHttpRequest) { // Mozilla, Safari, ...
xhr = new XMLHttpRequest();
} else if (window.ActiveXObject) { // IE 8 and older
xhr = new ActiveXObject("Microsoft.XMLHTTP");
}
/**********************************************************/
var data = "user="+user+"&id="+id;
xhr.open("POST", "message_read.php", true);
xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
xhr.send(data);
xhr.onreadystatechange = display_data;
function display_data() {
if (xhr.readyState == 4) {
if (xhr.status == 200) {
document.getElementById("message_box").innerHTML =xhr.responseText;
mymessage =setTimeout(display_message(user,id), 5000);
} else {
alert('There was a problem with the request.');
}
}
}
}

Request to external domain

I want to make a request to external domain,
parameter is sent correctely to php file (on external server)
but "request.responseText" allways empty,
thanks in advance (an example will be very apreciate)
<script type="text/javascript">
function get_XmlHttp() {
var xmlHttp = null;
if(window.XMLHttpRequest) { // for Forefox, IE7+, Opera, Safari, ...
xmlHttp = new XMLHttpRequest();
}
else if(window.ActiveXObject) { // for Internet Explorer 5 or 6
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
return xmlHttp;
}
function ajaxrequest() {
var request = get_XmlHttp(); // call the function for the XMLHttpRequest instance
var url = 'http://www.mydomain.fr/connexion.php?term=3334';
request.open("GET", url, true); // define the request
request.send(null); // sends data
request.onreadystatechange = function() {
if (request.readyState == 4) {
//response allways empty
document.getElementById("context").innerHTML = request.responseText;
}
}
}
window.onload = ajaxrequest();
</script>
<div id="context"></div>

by default you cannot just load data from another server, however if the server is configured to allow cross origin requests then you'll be good to go.
Take a read through the info here
http://www.html5rocks.com/en/tutorials/cors/

How to parse json from a url

I have a url contain all the json format.
http://api.musixmatch.com/ws/1.1/track.lyrics.get?apikey=d34fb59a16877bd1c540aa472491825b&track_id=12414632
function load() {
dashcode.setupParts();
var link = 'http://api.musixmatch.com/ws/1.1/track.search?apikey=d34fb59a16877bd1c540aa472491825b&q_track=back%20to%20december&page_size=10';
req.open = ("GET", link, false);
req.onreadystatechange = readXML();
req.send(null);
}
function readXML(){
alert(req.responseText);
}
this code keep saying null all the time.
Are there any way that i can retrieved those json text

The problem is with req.onreadystatechange = readXML();. You're assigning the result of the function instead of the function itself (as a callback).
You want req.onreadystatechange = readXML;. Though I must say I'm not sure how this code is supposed to work. Not in terms of how the XHR is made, nor with regards to the external domain.

Correct usage is as follows.You can check this link http://jsfiddle.net/UH4KY/1/ The link will alert undefined since cross domain scripting is not allowed .You can set the Access-Control-Allow-Origin and test the code.
function readXML(req) {
alert(req);
}
function load() {
var xmlhttp;
if (window.XMLHttpRequest) { // code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp = new XMLHttpRequest();
}
else { // code for IE6, IE5
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
var link = 'http://api.musixmatch.com/ws/1.1/track.search?apikey=d34fb59a16877bd1c540aa472491825b&q_track=back%20to%20december&page_size=10';
//req.open = ("GET", link, false);
xmlhttp.onreadystatechange = function(){ alert(xmlhttp.responseText); }
xmlhttp.open("GET", link, false);
xmlhttp.send(null);
}

Post Method XMLHttpRequest Forces Login Dialog(IE issue)

We are running windows IIS 6 and use it's native ability to protect files with Windows Authentication as our login method.
It works fine, except that when I try to post method XMLHttpRequest from IE i get the login dialog again, which causes the request to fail.
The weird thing is that Mozilla and Safari work well.
Is there something I can do with the headers or something to make IIS recognize it as the same session, and not promt a re-login?
function ajaxQuery(method, url, params, asynchronous, readyFunction, is_done) {
if (asynchronous == null) {
asynchronous = true;
}
//alert("URL: "+url);
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) {
readyFunction(xmlhttp.responseText);
if (is_done) {
is_done("ok");
}
}
}
if (method.toLowerCase() == "get") {
url += "?" + params;
params = null;
}
debug = url;
xmlhttp.open(method, url, asynchronous);
if (method.toLowerCase() == "post") {
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.setRequestHeader("Content-length", params.length);
xmlhttp.setRequestHeader("Connection", "close");
debug = params.length;
}
xmlhttp.send(params);
}

Check the response headers coming back. We had the same problem with an app that was (intentionally) returning a 401 code. IIS caught that code and added the WWW-Authenticate header which forces IE to display the login. We were able to fix it by returning 403 instead.