AJAX function with without jQuery. JS only.

ajax.js

var ajax = {
   load : function() {
     var xhr;
         
        if(typeof XMLHttpRequest !== 'undefined') xhr = new XMLHttpRequest();
        else {
            var versions = ["MSXML2.XmlHttp.5.0", 
                            "MSXML2.XmlHttp.4.0",
                            "MSXML2.XmlHttp.3.0", 
                            "MSXML2.XmlHttp.2.0",
                            "Microsoft.XmlHttp"]
 
             for(var i = 0, len = versions.length; i < len; i++) {
                try {
                    xhr = new ActiveXObject(versions[i]);
                    break;
                }
                catch(e){}
             } // end for
        }
         
        xhr.onreadystatechange = ensureReadiness;
         
        function ensureReadiness() {
            if(xhr.readyState < 4) {
                return;
            }
             
            if(xhr.status !== 200) {
                return;
            }
 
            // all is well  
            if(xhr.readyState === 4) {
                callback(xhr);
            }           
        }
         
        xhr.open('GET', url, true);
        xhr.send('');
   },
 
   otherMethod : someFunction() {
// paste here
   }
}
 
ajax.load();

// example call. Our simplified "load" function accepts a URL and CALLBACK parameter.
ajax.load('test.txt', function(xhr) {
    document.getElementById('container').innerHTML = xhr.responseText;
});