Changing CSS properties 'on-the-fly'

Question

I've got this vertical slideshow navigable by up/down arrows. there's 7 items (divs) inside the slideshow's container div but only 3 of them are visible at a time. In truth, this slideshow is a menu - from the 3 items visible, the one in the middle is the one clickable, which will load content in a div somewhere else in the page.

Now, since there are 3 items and only the 2nd item (middle one) is clickable, I need to create a difference between them. So, I thought of changing the items border/border-radius like this:

The problem is that I don't have a clue on how to do that since the divs are constantly changing place in the visible area. I really need help here.

HTML markup:

<div id="rocksType_btns">
    <div id="rocksType_btnUp"></div>
    <div id="rocksType_btnDown"></div>
</div>

<div id="rocksType_subtypeSlider">
    <div id="rocksType_DBitems_container">
        <div id="rocksType_DB_1" class="rocksType_DBitem">Item 1</div>
        <div id="rocksType_DB_2" class="rocksType_DBitem">Item 2</div>
        <div id="rocksType_DB_3" class="rocksType_DBitem">Item 3</div>
        <div id="rocksType_DB_4" class="rocksType_DBitem">Item 4</div>
        <div id="rocksType_DB_5" class="rocksType_DBitem">Item 5</div>
        <div id="rocksType_DB_6" class="rocksType_DBitem">Item 6</div>
        <div id="rocksType_DB_7" class="rocksType_DBitem">Item 7</div>
    </div>
</div> <!-- End of id="rocksMenu_subtypeSlider" -->

I already have the CSS code defined for the before/current/after states - just need to assign them.

Here's a Fiddle.

Thanx.

Pedro

Answer 1

Try something like this instead...

HTML:

<div id="viewport">
    <ul id="list">
        <li class="above">Foo</li>
        <li class="selected">Bar</li>
        <li class="below">Barf</li>
        <li>Boo</li>
        <li>Huh</li>
        <li>Wha</li>
        <li>Oh</li>
    </ul>
</div>
<a href="#" id="up">UP</a> -- <a href="#" id="down">DOWN</a>

CSS:

#viewport{
    height: 175px;
    overflow: hidden;
    padding: 0;
}

ul{
    list-style-type: none;
    padding: 0;
    margin: 0;
}

li{
    border: 1px solid #ccc;
    width: 70px;
    height: 50px;
    line-height: 50px;
    padding: 0 0 0 30px;
    margin: 5px;
    font-size: 1.5em;
    color: #999;
    background-color: #fed;
}

li.selected{
    border-radius: 20px;
    background-color: #fe0
}

li.above{
    border-radius: 10px;
    border-top-left-radius: 35px;    
}

li.below{
    border-radius: 10px;
    border-bottom-left-radius: 35px;    
}

JS:

var viewport = $('#viewport'),
    list = $('#list'),
    itemHeight = $('li', list).first().outerHeight(),
    btnUp = $('#up'),
    btnDown = $('#down'),
    busy = false,
    selected, above, below;

var update = function(){
    selected = $('li:nth-of-type(2)', list).addClass('selected', 200);
    above = selected.prev().addClass('above', 200);
    below = selected.next().addClass('below', 200); 
    setTimeout(function(){ busy = false; }, 200);
};

var goUp = function(){
    if(busy) return; else busy = true;
    $('li', list).removeClass('selected above below');
    list.animate({marginTop: -itemHeight}, 600, 'easeOutBounce', function(){ 
        list.css({marginTop: 0}).append($('li', list).first());
        update();
    });
}
var goDown = function(){
    if(busy) return; else busy = true;
    $('li', list).removeClass('selected above below');
    list
        .css({marginTop: -itemHeight})
        .prepend($('li',list).last())
        .animate({marginTop: 0}, 600, 'easeOutBounce', update);
}
btnUp.on('click', goUp);  
btnDown.on('click', goDown);

Fiddle here. Slightly fancier version.

I think the only way to do this is to keep track of what's what, instead of building it around animation.

Answer 2

Check out my alterations.

UPDATED: link to include managing style for prev and next classes

UPDATED: link to remove garish colours

http://jsfiddle.net/M3QkB/5/

Here is what I have changed, obviously styling remains to be completed:

In the up method:

    $('.rocksType_DBitem').removeClass('current');
    $('.rocksType_DBitem').removeClass('before');
    $('.rocksType_DBitem').removeClass('after');
    var middleRock = rocksType_place;
    rocksType_place--;           
    $('#rocksType_DBitems_container :eq(' + middleRock + ')').addClass('current');
    $('.current').prevAll().addClass('before');
    $('.current').nextAll().addClass('after');

In the down method:

    $('.rocksType_DBitem').removeClass('current');
    $('.rocksType_DBitem').removeClass('before');
    $('.rocksType_DBitem').removeClass('after');
    rocksType_place++;
    var middleRock = rocksType_place + 1;        
    $('#rocksType_DBitems_container :eq(' + middleRock + ')').addClass('current');
    $('.current').prevAll().addClass('before');
    $('.current').nextAll().addClass('after');

The common code can be refactored to functions such as cleaning the classes we add