使用jQuery仿苹果官网焦点图特效

#gallery{
    /* CSS3 Box Shadow */
    -moz-box-shadow:0 0 3px #AAAAAA;
    -webkit-box-shadow:0 0 3px #AAAAAA;
    box-shadow:0 0 3px #AAAAAA;
    /* CSS3 Rounded Corners */
    -moz-border-radius-bottomleft:4px;
    -webkit-border-bottom-left-radius:4px;
    border-bottom-left-radius:4px;
    -moz-border-radius-bottomright:4px;
    -webkit-border-bottom-right-radius:4px;
    border-bottom-right-radius:4px;
    border:1px solid white;
    background:url(img/panel.jpg) repeat-x bottom center #ffffff;
    /* The width of the gallery */
    width:920px;
    overflow:hidden;
}
#slides{
    /* This is the slide area */
    height:400px;
    /* jQuery changes the width later on to the sum of the widths of all the slides. */
    width:920px;
    overflow:hidden;
}
.slide{
    float:left;
}
#menu{
    /* This is the container for the thumbnails */
    height:45px;
}
ul{
    margin:0px;
    padding:0px;
}
li{
    /* Every thumbnail is a li element */
    width:60px;
    display:inline-block;
    list-style:none;
    height:45px;
    overflow:hidden;
}
li.inact:hover{
    /* The inactive state, highlighted on mouse over */
    background:url(img/pic_bg.png) repeat;
}
li.act,li.act:hover{
    /* The active state of the thumb */
    background:url(img/active_bg.png) no-repeat;
}
li.act a{
    cursor:default;
}
.fbar{
    /* The left-most vertical bar, next to the first thumbnail */
    width:2px;
    background:url(img/divider.png) no-repeat right;
}
li a{
    display:block;
    background:url(img/divider.png) no-repeat right;
    height:35px;
    padding-top:10px;
}
a img{
    border:none;
}

$(document).ready(function(){
    /* This code is executed after the DOM has been completely loaded */
    var totWidth=0;
    var positiOns= new Array();
    $('#slides .slide').each(function(i){
        /* Traverse through all the slides and store their accumulative widths in totWidth */
        positions[i]= totWidth;
        totWidth += $(this).width();
        /* The positions array contains each slide's commulutative offset from the left part of the container */
        if(!$(this).width())
        {
            alert("Please, fill in width & height for all your images!");
            return false;
        }
    });
    $('#slides').width(totWidth);
    /* Change the cotnainer div's width to the exact width of all the slides combined */
    $('#menu ul li a').click(function(e,keepScroll){
            /* On a thumbnail click */
            $('li.menuItem').removeClass('act').addClass('inact');
            $(this).parent().addClass('act');
            var pos = $(this).parent().prevAll('.menuItem').length;
            $('#slides').stop().animate({marginLeft:-positions[pos]+'px'},450);
            /* Start the sliding animation */
            e.preventDefault();
            /* Prevent the default action of the link */
            // Stopping the auto-advance if an icon has been clicked:
            if(!keepScroll) clearInterval(itvl);
    });
    $('#menu ul li.menuItem:first').addClass('act').siblings().addClass('inact');
    /* On page load, mark the first thumbnail as active */
    /*****
     *
     *    Enabling auto-advance.
     *
     ****/
    var current=1;
    function autoAdvance()
    {
        if(current==-1) return false;
        $('#menu ul li a').eq(current%$('#menu ul li a').length).trigger('click',[true]);    // [true] will be passed as the keepScroll parameter of the click function on line 28
        current++;
    }
    // The number of seconds that the slider will auto-advance in:
    var changeEvery = 10;
    var itvl = setInterval(function(){autoAdvance()},changeEvery*1000);
    /* End of customizations */
});