browser authentication popup in javascript

Question

I have sent cross domain POST request It needs authentication. By xhr

var xmlhttp = new XMLHttpRequest(),
    method = 'POST',
    url = 'http://192.168.1.54:7080/services/pdf/234';

xmlhttp.open(method, url, true, 'admin', 'admin');
xmlhttp.onreadystatechange = function () {
    if (xmlhttp.readyState !== XMLHttpRequest.DONE) {
        return;
    }
    if (xmlhttp.status !== 200) {
        return;
    }
    console.log(xmlhttp.responseText);
};
xmlhttp.send("fname=Henry&lname=Ford");

I have put Credentials with xmlhttp.open method, But still it open browser authentication popup.

I want to give post request with username and password to get response.