var progressBar = null;
for (var i = 0; i <= 100; i ++) {
    progressBar = new ProgressBar();
    progressBar.label = "Progress: "+i+"%";
    progressBar.appendTo(document.querySelector(".container"));
    progressBar.setValue(i);
}

var value = 0, direction = false, step = 1;

progressBar = new ProgressBar();
progressBar.label = "Live";
progressBar.appendTo(document.querySelector(".container"));

var intv = window.setInterval(function() {
    if (direction) {
        value -= step;
    } else {
        value += step;
    }
    progressBar.setValue(value);
    if (value >= 100 || (value <= 0 && direction))
        direction = !direction;
},33);