Get request without cookies

[th.dude]

hey guys,

any idea why this snippet returns the request page with cookies, showing logged in user even after sending empty cookie header?

var request = false;
request = new XMLHttpRequest();

    request.open("GET","index.html",1);
request.setRequestHeader("Cookie","");

    request.onreadystatechange = function() {
      if(request.readyState == 4) {

  re = request.responseText; 
alert(re);
	}
    }
request.send(null);