(function(){
    shuffle = function(array) {
        var i = array.length;
        while(i){
            var j = Math.floor(Math.random()*i);
            var t = array[--i];
            array[i] = array[j];
            array[j] = t;
        }
        return array;
    }

    var ads = [];
    if (ads.length < 1) return;

    var tmp = [];
    for (var i = 0; i < ads.length; i++) {
        for (var j = 0; j < ads[i].weight; j++) {
            tmp.push(ads[i]);
        }
    }

    var ad = shuffle(tmp).shift();
    document.getElementById('ad-zone-40').innerHTML = '<a href="' + ad.url +'" target="' + ad.target +'"><img src="' + ad.src +'" alt="' + ad.alt +'" /></a>';
})();