$(document).ready(function() {

    var $slider = $('#slider'),

        $prev = $('#prev'),

        $next = $('#next'),

        $slide = $slider.find('div');

    var currentSlide = 0,

        allSlides = $slider.find('div').length - 1; // index start from 0

    $slider.find('div').eq(0).show();

    function nextSlide() {

​

      if(currentSlide < allSlides) {

          $slide.eq(currentSlide).fadeOut(200);      

          $slide.eq(currentSlide + 1).fadeIn(200);

          currentSlide+=1;   

      }

​

    }

    function prevSlide() {      

      if(currentSlide > 0) {

          $slide.eq(currentSlide).fadeOut(200);      

          $slide.eq(currentSlide - 1).fadeIn(200);

          currentSlide-=1;   

      }

    }

  $next.on('click', nextSlide);

  $prev.on('click', prevSlide);

​

});