progress_bar_example.js

function move(pb) {
    pb.style.width = "0%"
    setTimeout(function () {
        console.log("start")
        var width = 1;
        var id = setInterval(frame, 50);

        function frame() {
            if (width >= 100) {
                clearInterval(id);
                console.log("done")
            } else {
                width++;
                pb.style.width = width + '%';
            }
        }
    }, 1000)
}