'Content-Length: 0', Javascript, XMLHttpRequest, Django REST API - django

Question

I wish I can find some assistance with my code.
I have set up a Database on mySQL, and connected it to Django REST. Those both work as expected, and I can access the REST with Firefox REST Client with it returning the correct tables from the database.
I have started working for user interface with html and javascript and I have encountered a problem I am unable to solve. I am a student, and this is part of my school work, but unfortunately my teachers are unavailable at the moment due summer vacations and I am eager to continue my project. Hence I am askin for Your assistance.
As I have tested the Django REST through Firefox REST Client, I am sure the database and REST service is not at fault so here we come to my code.
I seem to be able to get connection to the REST Service, giving me code 200 and state 4 (pictures linked underneath)
ReadyStateChange + ReadyState console.logs
Picture 2 shows that my GET request gets stuck on OPTIONS, instead of executing the correct request.
200 OPTIONS
However I am unable to pull data out, giving me 'Content-Length: 0'.
Originally I thought the issue would be cross-domain request problem until my fellow student said he does not think it is, however he was unable to find solution for my code either.
I am trying to find reason and workaround for this error, and if you guys do have idea why this is happening I would deeply appriciate your help!
Here is my code:
<div id="demo"></div>
<script>
loadData() //function kutsu
function loadData(){
if (window.XMLHttpRequest) {
// code for modern browsers
xmlhttp = new XMLHttpRequest();
} else {
// code for old IE browsers
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
var url = "http://127.0.0.1:8000/vamkrs/";
xmlhttp.open("GET", url, true);
xmlhttp.withCredentials = true;
xmlhttp.setRequestHeader("Authorization", "Basic " + btoa("username:password"));
xmlhttp.send();
setTimeout(xmlhttp.onreadystatechange = function() {
console.log(this.status);
console.log(this.readyState);
if (this.readyState == 4 && this.status == 200) {
var myData = JSON.parse(this.responseText);
document.getElementById("demo").innerHTML = myData.responseText(); }
},1500);
/*
xmlhttp.onreadystatechange = function(){
console.log(this.status);
if (this.readyState == 4 && this.status == 200) {
var myData = JSON.parse(this.responseText);
document.getElementById("demo").innerHTML = myData.responseText();}
}; */
}
</script>
Ps. Sorry, English is not my native language so some spelling mistakes might have been made
Pss. First time posting here, I apologize if mistakes were made on the post