Cannot retrieve text from xampp server because XMLHttprequest.readystate always returns ‘undefined’

I tried to access a .txt file stored in the htdocs folder of my xampp installation using only Javascript and no PHP. I only intend to use ajax to process a text file stored in server. This is my javascript code to make an asynchronous request:

(function(global){
    var ajaxUtils = {};
    function getRequestObject(){
        if(window.XMLHttpRequest){
            return (new XMLHttpRequest());
        }
        else{
            global.alert('Ajax is not supported!');
            return(null);
        }
    }

    ajaxUtils.sendGetRequest = function(requestUrl, responseHandler){
        var request = getRequestObject();
        request.onreadystatechange = function(){
            handleResponse(request, responseHandler);
        };
        request.open("GET",requestUrl,true);
        request.send(null);
    }

    function handleResponse(request, responseHandler){
        console.log(request.readystate + " " + request.status);
        if((request.readystate == 4) && (request.status == 200)){
            responseHandler(request);
        }
    }

    global.$ajaxUtils = ajaxUtils;
})(window);

This is how I passed parameters to ajaxUtils.sendGetRequest():

document.addEventListener("DOMContentLoaded", function(event){
    document.querySelector("button").addEventListener('click', function(){
        this.textContent='Said it!';
        $ajaxUtils.sendGetRequest('http://localhost/ajax/file.txt',function(request){
            var name = request.responseText;
            var message = "<h2>Hello " + name + '!</h2>';
            document.getElementById('content').innerHTML=message;
        });
    });
});

The code didn’t work and this is what I got in the console: request.readystate always returns ‘undefined’

‘readystate’ property of XMLHttprequest can have values 0,1,2,3, or 4, but here it always returns ‘undefined’. Does anybody know why this happened?