Sort json objects by priority then randomize everything els

Maybe someone can help. Can't figure out this by my self :( I have list of json objects:

{"widget_foto": {"photos": [
    {
        "picThumb": "../../preview_stuff/img/widget-3-1.png",
        "picOrig": "../../preview_stuff/img/widget-3-1.png",
        "galeryUrl": "",
        "shareUrl": "",
        "priority": 0
    },
    {
        "picThumb": "../../preview_stuff/img/widget-3-2.png",
        "picOrig": "../../preview_stuff/img/widget-3-2.png",
        "galeryUrl": "",
        "shareUrl": "",
        "priority": 2
    },}}

I need to order objects by priority, what I have done already, but I can't figure out how to randomize objects that have priority 0 or if object priorities are equal.

Here's my code so far.

$(function(){
var url="../json/foto.json";
$.getJSON(url, function(json){
    var fotoWidget = json.widget_foto;
    var widget3 = ".col-widget-3" + " ";

    //Populate content
    var byPriority = fotoWidget.photos.slice(0);

    byPriority.sort(function(a,b){
        return b.priority - a.priority;
    });
    $.each(byPriority, function(index, value){
        $(widget3 + ".widget-3-" + (index + 1)).css({"background-image": "url(images/" + value.picOrig + ")"});
    });
});

Any help will be apriciated.