XHR

xhr.js

var resource = "http://my-service/data.json";

var xhr = new XMLHttpRequest();
xhr.onprogress = updateProgress;
xhr.onreadystatechange = updateReadyState;

xhr.open('GET', resource, true);
xhr.send();

function updateProgress (e) {
    if (e.lengthComputable){
        var progress = Math.round((e.loaded / e.total) * 100);
        console.log(progress + "%");
    }
}

function updateReadyState(e) {
    if (xhr.readyState === 4) {
        alert("done");
    }
};