function previous(){
	
	new_page = parseInt($('#current_page').val()) - 1;
	//if there is an item before the current active link run the function
	if($('.active_page').prev('.page_link').length==true){
		go_to_page(new_page);
	}
	
}

function next(){
	new_page = parseInt($('#current_page').val()) + 1;
	//if there is an item after the current active link run the function
	if($('.active_page').next('.page_link').length==true){
		go_to_page(new_page);
	}
	
}
function go_to_page(page_num){
	//get the number of items shown per page
	var show_per_page = parseInt($('#show_per_page').val());
	
	//get the element number where to start the slice from
	start_from = page_num * show_per_page;
	
	//get the element number where to end the slice
	end_on = start_from + show_per_page;
	
	//hide all children elements of content div, get specific items and show them
	$('#content_pagenav').children().css('display', 'none').slice(start_from, end_on).css('display', 'block');
	
	/*get the page link that has longdesc attribute of the current page and add active_page class to it
	and remove that class from previously active page link*/
	$('.page_link[longdesc=' + page_num +']').addClass('active_page').siblings('.active_page').removeClass('active_page');
	
	//update the current page input field
	$('#current_page').val(page_num);
}