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javascript slider working ?

Posted on 2009-05-07
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Last Modified: 2012-08-14
following code is the javascript code for slider horizontal.
i need to know how this code is working ?
anybody can explain will be grateful .

i know something  javascript but this is a bit more complex.

Thanks
$.fn.drag_slider = function (wrapperSelector) {
    function repeat(str, num) {
        return new Array( num + 1 ).join( str );
    }
  
    return this.each(function () {
        var $wrapper = $(wrapperSelector, this),
            $slider = $wrapper.find('ul'),
            $items = $slider.find('li'),
            $single = $items.filter(':first'),
            
            singleWidth = $single.outerWidth(), //parseInt($single.width()) + parseInt($single.css('padding-left')) + parseInt($single.css('padding-right')),
            visible = Math.ceil($wrapper.innerWidth() / singleWidth)    <!--note: doesnt include padding or border-->
            currentPage = 1,
            pages = Math.ceil($items.length / visible);            
 
        // 1. Pad so that 'visible' number will always be seen, otherwise create empty items
        if (($items.length % visible) != 0) {
            $slider.append(repeat('<li class="empty" />', visible - ($items.length % visible)));
            $items = $slider.find('> li');
        }
 
        // 2. Top and tail the list with 'visible' number of items, top has the last section, and tail has the first
        $items.filter(':first').before($items.slice(- visible).clone().addClass('cloned'));
        $items.filter(':last').after($items.slice(0, visible).clone().addClass('cloned'));
        $items = $slider.find('> li'); // reselect
        
        // 3. Set the left position to the first 'real' item
        // $wrapper.css('scrollLeft', singleWidth * visible); // * -1
        $wrapper.get(0).scrollLeft = singleWidth * visible;
        
        // 4. Bind to the forward and back buttons
        $('a.back', this).click(function () {
            return gotoPage(currentPage - 1);                
        });
        
        $('a.forward', this).click(function () {
            return gotoPage(currentPage + 1);
        });
        
        // 5. paging function
        function gotoPage(page) {
            var dir = page < currentPage ? -1 : 1, // page < currentPage ? 1 : -1,
                n = Math.abs(currentPage - page),
                left = singleWidth * dir * visible * n;
           // alert(page);
            // console.log('currentPage', currentPage, 'left', left, 'n', n);
            
            $wrapper.filter(':not(:animated)').animate({
                scrollLeft : '+=' + left
            }, 500, function () {
                if (page == 0) {
                    currentPage = pages;
                    // $wrapper.css('scrollLeft', singleWidth * visible * pages); //  * -1
                    this.scrollLeft = singleWidth * visible * pages;
                } else if (page > pages) {
                    currentPage = 1;
                    this.scrollLeft = singleWidth * visible; //  * -1
                    // $wrapper.css('scrollLeft', singleWidth * visible); //  * -1
                    // reset back to start position
                } else {
                    currentPage = page;
                }
            });                
            
            return false;
        }
        
        // create a public interface to move to a specific page
        $(this).bind('goto', function (event, page) {
            gotoPage(page);
        });
    });  
};
 
$(function () {
    $('#scrollButtons > div').before('<a href="#" class="back"><img src="images/panel-arrow-l.jpg" width="28" height="52" class="scrollLeft" /></a>').after('<a class="forward" href="#"><img src="images/panel-arrow-r.jpg" width="28" height="52"  class="scrollRight" /></a>').parent().drag_slider('> div');
});

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Question by:hiddenpearls
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4 Comments
 
LVL 12

Expert Comment

by:alien109
ID: 24325091
is there a certain area that you are confused on? maybe you can be more specific.
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Author Comment

by:hiddenpearls
ID: 24326104
$(function () {
    $('#scrollButtons > div').before('<a href="#" class="back"><img src="images/panel-arrow-l.jpg" width="28" height="52" class="scrollLeft" /></a>').after('<a class="forward" href="#"><img src="images/panel-arrow-r.jpg" width="28" height="52"  class="scrollRight" /></a>').parent().drag_slider('> div');
});

this part is used to display two scroll buttons  at left and right side.
what is this parent().drag_slider('> div'); ?  in the above part.

this is the starting point of the script i think so .
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Accepted Solution

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alien109 earned 500 total points
ID: 24326958
$('#scrollButtons > div').before('<a href="#" class="back"><img src="images/panel-arrow-l.jpg" width="28" height="52" class="scrollLeft" /></a>').after('<a class="forward" href="#"><img src="images/panel-arrow-r.jpg" width="28" height="52"  class="scrollRight" /></a>').parent().drag_slider('> div');

This line selects div tags which are direct descendants of the scrollButtons object and then inserts the html for creating the buttons before and after the element. It then calls the parent of the selected element, and executes the drag_slider function on div tags which are direct descendants (essentially itself).

The code structure is actually a bit redundant.

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Author Comment

by:hiddenpearls
ID: 24327664
can there be any alternate to this above code ?
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