javascript ajax request without framework

Does anyone know how to make ajax request function that works cross-browser WITHOUT using a javascript framework like jQuery, etc.?

The `XMLHttpRequest` object isn't actually all that complicated to use. To be broadly compatible, you have to play a bit of a game to create the object, but after that it's fairly straightforward for simple operations.

Microsoft has examples on the [MSDN page for `XMLHttpRequest`][1], including a function for creating the object in a cross-browser way that supports early versions of IE. Here's their example:

function getXMLHttpRequest()
{
if (window.XMLHttpRequest) {
return new window.XMLHttpRequest;
}
else {
try {
return new ActiveXObject("MSXML2.XMLHTTP.3.0");
}
catch(ex) {
return null;
}
}
}

function handler()
{
if (oReq.readyState == 4 /* complete */) {
if (oReq.status == 200) {
alert(oReq.responseText);
}
}
}

var oReq = getXMLHttpRequest();

if (oReq != null) {
oReq.open("GET", "http://localhost/test.xml", true);
oReq.onreadystatechange = handler;
oReq.send();
}
else {
window.alert("AJAX (XMLHTTP) not supported.");
}

I'm not suggesting the above exemplifies best practices (Microsoft seems to have their MSDN examples largely written by very, very inexperienced engineers), but it gives you a starting point. For instance, the above requires that the response status be 200 for success, where of course the HTTP specification is clear that anything the 200 <= n <= 299 range is "success".

[1]:

[To see links please register here]

i often use this method for sending and receiving only json in modern browsers (no old-ie's)

function aj(method, url, data, cb){

var xhr = new XMLHttpRequest();
xhr.onreadystatechange = readystatechange;
xhr.open(method, url);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.send(data && JSON.stringify(data));

function readystatechange(){
if(this.readyState === this.DONE) {

switch(this.status){
case 200:
if(this.getResponseHeader('Content-Type').split(';')[0] !== 'application/json'){
return cb("unexpected Content-Type: '" + this.getResponseHeader('Content-Type') + "'", null);
}
return cb(null, JSON.parse(this.response));

case 401:
location.href = '/authentication/login';
return;

default:
return cb("unexpected status: " + this.status + "", null);
}
}
}//readystatechange
}