Making feed slider to use random posts instead of first ones

OK i made a slider using code i found somewhwhere over net to display posts from two labels from blogger feed api. So there is a problem that this code is a little bit confusing to me and I am asking how to anapt this code to pick for egxample random 7 posts.

<style type="text/css">
ul.featured-widget-list,ul.featured-widget-list li{margin:0;padding:0;list-style:none;position:relative }ul.featured-widget-list li{display:none}ul.featured-widget-list li:nth-child(1){display:block;line-height:0}ul.featured-widget-list img{border:0;width:100%;height:auto}ul.featured-widget-list .featuredbg{width:100%;height:100%;position:absolute;z-index:2;left:0;top:0;opacity:.6;background-image:url(http://ift.tt/1O3RgW0);background-position:0% 100%;background-repeat:repeat-x}ul.featured-widget-list .featuredbg:hover{opacity:.1}ul.featured-widget-list h5{position:absolute;left:0;right:0;text-align:center;bottom:10px;z-index:2;color:#fff;margin:0;text-transform: capitalize;padding:10px 20px;line-height:1.9em;letter-spacing:0.3px;font: 600 16px, sans-serif;overflow:hidden}ul.featured-widget-list li:hover h5{bottom:30px}ul.featured-widget-list .featured-meta{font: 11px , sans-serif;letter-spacing:0.3px;position:absolute;bottom:0;left:0;right:0;text-align:center;z-index:2;color:#fff;opacity:0}ul.featured-widget-list h5, ul.featured-widget-list .featured-meta {display:none!important;visibility:hidden!imporant;opacity:0!important;height: 0!important;}ul.featured-widget-list li:hover .featured-meta{bottom:20px;opacity:1}.feat-buttons{position:absolute;top:50%;left:0;z-index:5;width:100%}
.feat-buttons a{text-indent:-9999px;margin:0 7px;width:15px;height:15px;padding:5px;background:#000;-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=60)";filter: alpha(opacity=60);-moz-opacity:0.6;-khtml-opacity:0.6;opacity:0.6;position:relative;-webkit-border-radius: 50%;-moz-border-radius: 50%;border-radius: 50%;}.feat-prev{float:left;}.feat-next{float:right;}.feat-buttons a.feat-prev::before, .feat-buttons a.feat-next::before{content:"";width:0;height:0;border-width:6px 7px;border-style:solid;border-color:transparent #fff transparent transparent;position:absolute;top:50%;margin-top:-6px;margin-left:-11px;left:50%}
.feat-buttons a.feat-next::before{border-color:transparent transparent transparent #fff;margin-left:-3px}
#slidecontainter {max-width: 270px;max-height: 270px;position:relative;margin: 0 auto;display: inline-block;}
#centerwrapckass{text-align:center;}
#spacebetweentwo{width:90px;display: inline-block;}
@media only screen and (max-width:448px){#spacebetweentwo{display:none!important;}}
</style>
<div id="centerwrapckass">
<div  id="slidecontainter" ><div id="featuredbwidget"></div></div>
<div  id="spacebetweentwo" ></div>
<div  id="slidecontainter" ><div id="featuredbwidget1"></div></div>
</div>
<script type='text/javascript'>
//<![CDATA[
featuredbwidget({
listURL:"",
featuredNum:7,
listbyLabel:"Познати%20велики%20песници",
feathumbSize:150,
interval:1000,
autoplay:false,
featuredID:"#featuredbwidget"
});
featuredbwidget({
listURL:"",/*ostaviti  prazno*/
featuredNum:7,
listbyLabel:"Данашњи%20песници",
feathumbSize:150,
interval:1000,
autoplay:false,
featuredID:"#featuredbwidget1"
});
function featuredbwidget(a) {
    (function(e) {
        var h = {
            listURL: "",
            featuredNum: 3,
            featuredID: "",
            feathumbSize: 300,
            interval: 5000,
            autoplay: false,
            loadingFeatured: "nextfeatured",
            pBlank: "http://ift.tt/1UcBnsV",
            byMonth: ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"],
            listbyLabel: false
        };
        h = e.extend({}, h, a);
        var g = e(h.featuredID);
        var d = h.featuredNum * 200;
        g.html('<div class="featslider"><ul class="featured-widget-list"></ul><div class="feat-buttons"><a href="#" class="feat-prev">Prev</a><a href="#" class="feat-next">Next</a></div></div>');
        var f = function(w) {
            var q, k, m, u, x, p, t, v, r, l = "",
                s = w.feed.entry;
            for (var o = 0; o < s.length; o++) {
                for (var n = 0; n < s[o].link.length; n++) {
                    if (s[o].link[n].rel == "alternate") {
                        q = s[o].link[n].href;
                        break
                    }
                }
                if ("media$thumbnail" in s[o]) {
                    u = s[o].media$thumbnail.url.replace(/\/s[0-9]+\-c/g, "/s" + h.feathumbSize + "-c")
                } else {
                    u = h.pBlank.replace(/\/s[0-9]+(\-c|\/)/, "/s" + h.feathumbSize + "$1")
                }
                k = s[o].title.$t;
                r = s[o].published.$t.substring(0, 10);
                m = s[o].author[0].name.$t;
                x = r.substring(0, 4);
                p = r.substring(5, 7);
                t = r.substring(8, 10);
                v = h.byMonth[parseInt(p, 10) - 1];
                l += '<li><a href="' + q + '"><div class="featuredbg"></div><img class="featuredthumb" src="' + u + '"/><h5>' + k + '</h5></a><div class="featured-meta"><span class="fdate"><span class="fday">' + t + '</span> <span class="fmonth">' + v + '</span> <span class="fyear">' + x + '</span></span> - <span class="fauthor">' + m + "</span></div></li>"
            }
            e("ul", g).append(l).addClass(h.loadingFeatured)
        };
        var c = function() {
            e(h.featuredID + " .feat-next").click()
        };
        var b = function() {
            e.get((h.listURL === "" ? window.location.protocol + "//" + window.location.host : h.listURL) + "/feeds/posts/summary" + (h.listbyLabel === false ? "" : "/-/" + h.listbyLabel) + "?max-results=" + h.featuredNum + "&orderby=published&alt=json-in-script", f, "jsonp");
            setTimeout(function() {
                e(h.featuredID + " .feat-prev").click(function() {
                    e(h.featuredID + " .featslider li:first").before(e(h.featuredID + " .featslider li:last"));
                    return false
                });
                e(h.featuredID + " .feat-next").click(function() {
                    e(h.featuredID + " .featslider li:last").after(e(h.featuredID + " .featslider li:first"));
                    return false
                });
                if (h.autoplay) {
                    var i = h.interval;
                    var j = setInterval(c, i);
                    e(h.featuredID + " .featslider li:first").before(e(h.featuredID + " .featslider li:last"));
                    e(h.featuredID + " .featslider").hover(function() {
                        clearInterval(j)
                    }, function() {
                        j = setInterval(c, i)
                    })
                }
                e("ul", g).removeClass(h.loadingFeatured)
            }, d)
        };
        e(document).ready(b)
    })(jQuery)
};
//]]>
</script>

Does anybody have any idea how to acomplish this? Probably need to use function Math.random(); and to make some foor loop to be sure that random values do not get duplicated. Thanks in advance this is very important for me to acomplish this task