AJAX - Return responseText - ajax

Question

I've seen the myriad threads sprawled across the Internet about the following similar code in an AJAX request returning undefined:
AJAX.onreadystatechange = function() {
if(AJAX.readyState == 4) {
if(AJAX.status == 200) {
var response = AJAX.responseText;
return response;
}
else {
window.alert('Error: ' + AJAX.status);
return false;
}
}
};
I know that I'm supposed to "do something with" responseText like writing it to the HTML. The problem: I don't have that luxury. This bit of code is intended to be inside of a generic method for running fast AJAX requests that way all the code for making an AJAX request doesn't have to written out over and over again (~40×) with the chance of a minor problem here or there that breaks the application.
My method HAS to explicitly return responseText "or else." No writing to HTML. How would I do this? Also, I'd appreciate a lack of plugs for JQuery.
What I'm looking for:
function doAjax(param) {
// set up XmlHttpRequest
AJAX.onreadystatechange = function() {
if(AJAX.readyState == 4) {
if(AJAX.status == 200) {
var response = AJAX.responseText;
return response;
}
else {
window.alert('Error: ' + AJAX.status);
return false;
}
}
};
// send data
}
...
function doSpecificAjax() {
var param = array();
var result = doAjax(param);
// manipulate result
}

Answer 1

Doing a little research I came across this SOF post:
Ajax responseText comes back as undefined
Based on that post, it looks like you may want to implement your ajax method like this:
function doRequest(url, callback) {
var xmlhttp = ....; // create a new request here
xmlhttp.open("GET", url, true); // for async
xmlhttp.onreadystatechange=function() {
if (xmlhttp.readyState==4) {
if (xmlhttp.status == 200) {
// pass the response to the callback function
callback(null, xmlhttp.responseText);
} else {
// pass the error to the callback function
callback(xmlhttp.statusText);
}
}
}
xmlhttp.send(null);
}
Then, you can call that method like this...
doRequest('http://mysite.com/foo', function(err, response) { // pass an anonymous function
if (err) {
return "";
} else {
return response;
}
});
This should return the responseText accurately. Let me know if this doesn't give you back the correct results.