Develop Reference

AJAX in Internet Explorer 11 - Don't cache

I have an issue with AJAX in the IE 11. My page is asking sone values via AJAX form the server using this code:
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");
}
xmlhttp.onreadystatechange = function ()
{
if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
{
doSomeThing();
}
}
xmlhttp.open("GET", "theURL", true);
xmlhttp.send();
In Chrome and Firefox it's working fine but the IE seems to cache the AJAX response and I get the same result, even if the page on the server changed.
Is there a way to disable the caching?

Add a random parameter to the url, such as a timestamp:
var url="//yoururl.com/";
url+="?"+new Date().getTime();

This was driving me crazy. I tried many cache busting techniques and setting cache headers. So many of these either did not work or were wild goose chases. The only solution I found which tested to work correctly was setting:
Header Pragma: no-cache
I hope it saves others with IE headaches.
BTW this is StackOverflow thread is great to shed light on the difference between Pragma and Cache-control:
Difference between Pragma and Cache-control headers?

xmlhttp.request fails to open local file

The following javascript used to work but now does not. xmlhttp.status is 0. The file "SBL_Stats.htm" resides in the same directory as the javascript.
I'm using firefox.
Can anyone help me out?
var filePath = "SBL_Stats.htm";
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
Log("Firefox");
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
Log("IE6");
}
xmlhttp.overrideMimeType('text/plain'); // don't scan for html
xmlhttp.open("GET",filePath,false); // false means sync request
xmlhttp.send(null);
if (xmlhttp.status != 200)
{
Log("get_SBL_Stats_Data failed: " + xmlhttp.status);
return "";
}

Thanks to dandavis who started me down the right track. The problem occurs because I was using local files. I guess that means using the file:: protocol as opposed to the the http:: protocol. No status is returned when accessing local files. Removing the status check corrects the problem. However I wanted to be able to detect if the file could be opened so I added a try catch block around the send call as follows...
try
{
xmlhttp.send(null);
}
catch(err)
{
Log("xmlhttp.send error " + err);
return "";
}

Tracking visitor with javascript

I have one master domain : www.domain-A.com
I have some domains that call a javascript file on this principal domain.
For example, www.domain-B.com use the file www.domain-A.com/file.js
In this file.js script, I'm trying to put cookie (that's ok) and send some data to www.domain-A.com like the query string, the referrer and the user agent.
I've use that code in my 'file.js' (found on W3School website) :
//Envoi des données
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");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
var json = xmlhttp.responseText;
}
}
xmlhttp.open("POST","http://www.domaine-A.com/script.php",true);
xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
xmlhttp.send(urlParams + "&" + infParams + "&" + u);
It's working very well on FF and Chrome. But, not on IE because I have this error :
This page is accessing information not under its control
So, I've look a little how analytics send data to Google and i seem's use a GIF or something like that but i don't know how to do it in the good way.
My goal is send data from domain-x.com to domain-a.com with javascript.

What version of GA are you using? If you are on analytics.js (Universal Analtyics) You can use ajax and the measurement protocol to call page views on the other site. The measurement protocol lets you make HTTP requests and send raw data right into to GA.
I have used it before to track interaction with interactive infographic that I had on another site.
For your case you can use the following paramaters
www.google-analytics.com/collect
v=1 // Version.
&tid=UA-XXXX-Y // Tracking ID / Web property / Property ID.
&cid=555 // Anonymous Client ID.
&t=pageview // Pageview hit type.
&dh=mydemo.com // Document hostname.
&dp=/home // Page.
&dt=homepage // Title.

Path issue in ajax ,in a wordpress site

I have a wordpress site
for ex, www.test.com
There is a js file (forms.js)in the script folder of mytheme folder.
ie (theme/mytheme/script/forms.js)
There is a mail.php page in mytheme folder
ie (theme/mytheme/mail.php)
Following is the content of forms.js
function submitFormToEmail()
{
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");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
//document.getElementById("results").innerHTML=xmlhttp.responseText;
alert("Form received, thank you!");
}
}
xmlhttp.open("GET","/mail.php",true);
xmlhttp.send();
}
I will call "submitFormToEmail",if we click a image in the page *www.test.com/hello_test*
Where "hello_test" page lies in theme/mytheme/.
But the mail.php is not working.
Let me know ,how can we set the path of mail.php in the function "submitFormToEmail", so that it will work

Calling /mail.php will look for the mail.php file at http://www.test.com/mail.php. Just fix the path?
Either directly code the correct path into the javascript file or use php to dynamically get it using get_bloginfo. There are several ways to do this, but probably the best way is to create a hidden element on the page that contains the url and then fetch this when building your ajax request. Otherwise you'd have to set php to parse js files and include it in there. Doesn't seem like a good way to me though.
get_bloginfo('template_url');

read txt file via client javascript

I'm new to javascript and trying to open a txt file into var and then inject it to html div...
I tried to use fopen but I didn't succeed.
<script type="text/javascript">
file = fopen(getScriptPath("info.txt"), 0);
file_length = flength(file);
var content = fread(file,file_length);
var div = document.getElementById("myDiv");
//alert(div);
div.innerHTML = "";
div.innerHTML = content;
</script>

Although it says xml request this works perfectly fine for txt files too (server and client side).
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET","YOUR_FILE.txt",false);
xmlhttp.send();
xmlDoc=xmlhttp.responseText;

JavaScript has none of the functions you are trying to use.
To read files on the server in JavaScript, you can use XMLHttpRequest.
There is no easy way to read files on the client machine.

abandoned question:
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET","YOUR_FILE.txt",false);
xmlhttp.send();
xmlDoc=xmlhttp.responseText;
by Freek8

For security reasons, Javascript is made so you can not do this. However, a person has made a workaround which may work and posted it here.
Ok, I realize, it only works for files that are publicly accessbile on the server, which I believe is not what you want to do. Still, if you do find a way, it will be a hack like this, but it could also be fixed to not work at any time.