Before inspecting examples, you should know two jQuery functions which i used most.

index() returns value is an integer indicating the position of the first element within the jQuery object relative to its sibling elements.

eq() selects of an element based on its position (index value).

Basicly i take selected trigger element's index value and match this value on images with eq method.

- FadeIn / FadeOut effect.

- Sliding effect.

- alternate Mousewheel response.

​html sample:

<ul class=images>

   <li>

      <img src=images/1.jpg alt=1 />

   </li>

   <li>

      <img src=images/2.jpg alt=2 />

   </li>

   ...

</ul>



<ul class=triggers>

   <li>1</li>

   <li>2</li>

   ...

</ul>

<span class=control prev>Prev</span>

<span class=control next>Next</span>

OPACITY EFFECT: jsFiddle.

css trick: overlapping images with position:absolute

ul.images { position:relative; }

  ul.images li { position:absolute; }

jQuery:

var target;

var triggers = $('ul.triggers li');

var images = $('ul.images li');

var lastElem = triggers.length-1;



triggers.first().addClass('active');

images.hide().first().show();



function sliderResponse(target) {

    images.fadeOut(300).eq(target).fadeIn(300);

    triggers.removeClass('active').eq(target).addClass('active');

}

SLIDING EFFECT: jsFiddle.

css trick: with double wrapper and use child as mask

.mask { float:left; margin:40px; width:270px; height:266px; overflow:hidden;  }

    ul.images { position:relative; top:0px;left:0px; }

    /* this width must be total of the images, it comes from jquery */

        ul.images li { float:left; }

jQuery:

var target;

var triggers = $('ul.triggers li');

var images = $('ul.images li');

var lastElem = triggers.length-1;

var mask = $('.mask ul.images');

var imgWidth = images.width();



triggers.first().addClass('active');

mask.css('width', imgWidth*(lastElem+1) +'px');



function sliderResponse(target) {

    mask.stop(true,false).animate({'left':'-'+ imgWidth*target +'px'},300);

    triggers.removeClass('active').eq(target).addClass('active');

}

Common jQuery response for both slider:

( triggers + next/prev click and timing )

triggers.click(function() {

    if ( !$(this).hasClass('active') ) {

        target = $(this).index();

        sliderResponse(target);

        resetTiming();

    }

});



$('.next').click(function() {

    target = $('ul.triggers li.active').index();

    target === lastElem ? target = 0 : target = target+1;

    sliderResponse(target);

    resetTiming();

});

$('.prev').click(function() {

    target = $('ul.triggers li.active').index();

    lastElem = triggers.length-1;

    target === 0 ? target = lastElem : target = target-1;

    sliderResponse(target);

    resetTiming();

});



function sliderTiming() {

    target = $('ul.triggers li.active').index();

    target === lastElem ? target = 0 : target = target+1;

    sliderResponse(target);

}



var timingRun = setInterval(function() { sliderTiming(); },5000);

function resetTiming() {

    clearInterval(timingRun);

    timingRun = setInterval(function() { sliderTiming(); },5000);

}