支持自动轮播播放的幻灯片

var glume = function(banners_id, focus_id) {
    this.$ctn = $('#' + banners_id);
    this.$focus = $('#' + focus_id);
    this.$adLis = null;
    this.$btns = null;
    this.switchSpeed = 5;//自动播放间隔(s)
    this.defOpacity = 1;
    this.crtIndex = 0;
    this.adLength = 0;
    this.timerSwitch = null;
    this.init();
};
glume.prototype = {
    fnNextIndex: function() {
        return (this.crtIndex >= this.adLength - 1) ? 0 : this.crtIndex + 1;
    },
    //动画切换
    fnSwitch: function(toIndex) {
        if (this.crtIndex == toIndex) {
            return;
        }
        this.$adLis.css('zIndex', 0);
        this.$adLis.filter(':eq(' + this.crtIndex + ')').css('zIndex', 2);
        this.$adLis.filter(':eq(' + toIndex + ')').css('zIndex', 1);
        this.$btns.removeClass('on');
        this.$btns.filter(':eq(' + toIndex + ')').addClass('on');
        var me = this;

        $(this.$adLis[this.crtIndex]).animate({
            opacity: 0
        }, 1000, function() {
            me.crtIndex = toIndex;
            $(this).css({
                opacity: me.defOpacity,
                zIndex: 0
            });
        });
    },
    fnAutoPlay: function() {
        this.fnSwitch(this.fnNextIndex());
    },
    fnPlay: function() {
        var me = this;
        me.timerSwitch = window.setInterval(function() {
            me.fnAutoPlay();
        }, me.switchSpeed * 1000);
    },
    fnStopPlay: function() {
        window.clearTimeout(this.timerSwitch);
        this.timerSwitch = null;
    },
    init: function() {
        this.$adLis = this.$ctn.children();
        this.$btns = this.$focus.children();
        this.adLength = this.$adLis.length;

        var me = this;
        //点击切换
        this.$focus.on('click', 'a', function(e) {
            e.preventDefault();
            var index = parseInt($(this).attr('data-index'), 10)
            me.fnSwitch(index);
        });
        this.$adLis.filter(':eq(' + this.crtIndex + ')').css('zIndex', 2);
        this.fnPlay();

        //hover时暂停动画
        this.$ctn.hover(function() {
            me.fnStopPlay();
        }, function() {
            me.fnPlay();
        });

        if ($.browser.msie && $.browser.version < 7) {
            this.$btns.hover(function() {
                $(this).addClass('hover');
            }, function() {
                $(this).removeClass('hover');
            });
        }
    }
};
var player1 = new glume('_banners', '_focus');