//主函数
var s = function() {
    var interv = 2000; //切换间隔时间
    var interv2 = 10; //切换速速
    var opac1 = 80; //文字背景的透明度
    var source = "fade_focus" //焦点轮换图片容器的id名称
    //获取对象
    function getTag(tag, obj) {
        if (obj == null) {
            return document.getElementsByTagName(tag)
        }
        else {
            return obj.getElementsByTagName(tag)
        }
    }
    function getid(id) {
        return document.getElementById(id)
    }
    var opac = 0, j = 0, t = 63, num, scton = 0, timer, timer2, timer3;
    var id = getid(source);

    var li = getTag("li", id);
    var div = document.createElement("div");
    var title = document.createElement("div");
    var span = document.createElement("span");
    var button = document.createElement("div");
    button.className = "button";
    for (var i = 0; i < li.length; i++) {
        var a = document.createElement("a");
        a.innerHTML = i + 1;
        a.onclick = function() {
            clearTimeout(timer);
            clearTimeout(timer2);
            clearTimeout(timer3);
            j = parseInt(this.innerHTML) - 1;
            scton = 0;
            t = 63;
            opac = 0;
            fadeon();
        }
        a.className = "b1";
        a.onmouseover = function() {
            this.className = "b2"
        }
        a.onmouseout = function() {
            this.className = "b1";
            sc(j)
        }
        button.appendChild(a);
    }
    //控制图层透明度
    function alpha(obj, n) {
        if (document.all) {
            obj.style.filter = "alpha(opacity=" + n + ")";
        }
        else {
            obj.style.opacity = (n / 100);
        }
    }
    //控制焦点按钮
    function sc(n) {
        for (var i = 0; i < li.length; i++) {
            button.childNodes[i].className = "b1"
        }
        button.childNodes[n].className = "b2";
    }
    title.className = "num_list";
    title.appendChild(span);
    alpha(title, opac1);
    id.className = "d1";
    div.className = "d2";
    id.appendChild(div);
    id.appendChild(title);
    id.appendChild(button);
    //渐显
    var fadeon = function() {
        opac += 5; div.innerHTML = li[j].innerHTML;
        span.innerHTML = getTag("img", li[j])[0].alt;
        alpha(div, opac);
        if (scton == 0) {
            sc(j); num = -2; scrolltxt(); scton = 1
        }
        if (opac < 100) {
            timer = setTimeout(fadeon, interv2)
        }
        else {
            timer2 = setTimeout(fadeout, interv);
        }
    }
    //渐隐
    var fadeout = function() {
        opac -= 5; div.innerHTML = li[j].innerHTML;
        alpha(div, opac);
        if (scton == 0) {
            num = 2;
            scrolltxt();
            scton = 1
        }
        if (opac > 0) {
            timer = setTimeout(fadeout, interv2)
        }
        else {
            if (j < li.length - 1) {
                j++
            }
            else {
                j = 0
            }
            fadeon()
        }
    }
    //滚动文字
    var scrolltxt = function() {
        t += num; span.style.marginTop = t + "px";
        if (num < 0 && t > 3) {
            timer3 = setTimeout(scrolltxt, interv2)
        }
        else if (num > 0 && t < 62) {
            timer3 = setTimeout(scrolltxt, interv2)
        }
        else {
            scton = 0
        }
    }
    fadeon()
}
//初始化
window.onload = s;