getnext.js

$(function() {
      
  $(".grid_3").each(function(){
    
    // .next finds the next Dom element in this case it would be another grid_3 element
    var next = $(this).next();
    
    var prev = $(this).prev();
    
    // Store this current element into a var called "that" so that "this" can be used in it's own handler
    var that = this;
    
    // Find the .next element in this specific element and call a click function
    $(this).find('.next').click(function() {
      // Hide the current parent element the variable set above for the grid_3 element
      $(that).hide();
      
      // Fade in the next element in the dom
      next.fadeIn();
    });
    
    // Reverse that sucka
    
    $(this).find('.prev').click(function() {
      $(that).hide();
      
      prev.fadeIn();
      
    });    
    
  });  
});