Trying to create custom jQuery text-scroller

Question

I'm trying to make a own custom js-text-scroller (I want the text to scroll to the left within a div and then repeat the scrolling again and again).

But I'm having some problems. I really can't put my finger on where I'm doing wrong or where I need new functionality. All the help that I can get is welcome.

Here's a fiddle example: http://jsfiddle.net/Na373/

the HTML:

<div class="wrap">
   <div class="scroll">
       <ul class="active">
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
           <li>Hello World</li>
       </ul>
   </div>

the JS:

$ul = $('.scroll ul');
//copys the existing ul and appends it after the existing one
$('.scroll').append($ul.clone().removeClass().addClass('not_active'));

function scroll() {
    $active = $('.scroll ul.active');

    $active.each(function() {
        $not_active = $('.scroll ul.not_active');

        // foreach time the function runs the ul goes "left: -1px;"
        var current_position = parseInt($(this).css('left'));
        var new_position = current_position - 1;
        $(this).css('left', new_position+'px');

        var parent_width = $(this).parent().outerWidth(); // gets the width of ".scroll"
        var width = $(this).outerWidth(); // gets the width of the "ul"
        var shown_all = current_position + width;

        // if the right corner of the "ul" are att the right corner of ".scroll"
        // this if statement executes and adds new existing class on the "ul.not_active"
        // and adds class ".active" instead
        // this means that there are 2 ul with the class active 
        //running simultaneously
        if (shown_all == parent_width) {
            $not_active.removeClass().addClass('active');
        }

        // here it checks if the "ul.active" have past its own length to left
        // Here im trying to make it "not_active" and put it after the existing ".active"
        //
        // <ul class="active">....</ul> ----> <ul class="not_active">...</ul>
        //
        // then put it after the other "ul.active"
        //
        //            <ul class="active
        // ---------> <ul class="not_active"></ul>
        //
        // So it all beginns from the beginning
        if (current_position == '-'+width) {
            $(this).removeClass().addClass('not_active').css('left', '0');
            $(this).insertAfter($('.scroll ul').next());
        }
    });
};
// And here I run the function
setInterval(scroll, 10);

CSS:

.wrap {  
    position: relative;
    padding: 10px 10px 10px;
    height: 18px;
    background: #000;
    color: #fff;
    overflow: hidden;
    width: 500px;
}
.scroll {
   width: 500px;
   white-space: nowrap;
}
.scroll ul {
    left: 0;
    position: relative;
    margin: 0;
    padding: 0;
    display: inline;
    list-style: none;
}
.scroll ul li {
    padding: 0;
    margin: 0;
    display: inline;
}

Answer 1

I now got a working example here: http://jsfiddle.net/s8TnL/

All response is more than welcome. I gladly receive response regarding performance and functionality.

HTML:

<div class="wrap">
<div class="scroll">
    <ul class="active">
        <li>Hello World</li>
        <li>Hello World</li>
        <li>Hello World</li>
        <li>Hello World</li>
        <li>Hello World</li>
        <li>Hello World</li>
        <li>Hello World</li>
    </ul>
</div>

CSS:

.wrap {
    position: relative;
    padding: 10px 10px 10px;
    height: 18px;
    background: #0BF397;
    color: #fff;
    overflow: hidden;
    width: 500px
}
.scroll {
    display: block;
    white-space: nowrap;
}
.scroll ul {
    position: relative;
    margin: 0;
    padding: 0;
    display: inline;
    list-style: none;
}
.scroll ul li {
    padding: 0;
    margin: 0;
    display: inline;
}

JS:

$ul = $('.scroll ul');
$('.scroll').append($ul.clone().removeClass().addClass('not_active'));

$ul.hover(function () {
    clearInterval(activate);
}, function () {
    activate = setInterval(scroll, 10);
});

function scroll() {
    $active = $('.scroll ul.active');

    $active.each(function () {
        $not_active = $('.scroll ul.not_active');
        var offset = $(this).offset();

        var current_position = offset.left;
        var new_position = current_position - 1;
        $(this).offset({
            left: new_position
        });

        var parent_width = $(this).parent().outerWidth();
        var width = $(this).outerWidth();

        var shown_all = current_position + width;

        if (shown_all == parent_width) {
            $not_active.removeClass().addClass('active').offset({
                left: parent_width
            });
        }

        if (current_position == '-' + width) {
            $(this).removeClass().addClass('not_active');
        }
    });
};

activate = setInterval(scroll, 10);

Answer 2

I think your problem is the condition in the following if statement

if (shown_all == parent_width) {

As far as I can tell, shown_all = current_position + width, means that shown_all will start at 0 + width of ul, and will end up at 0. With the current code, the if statement is never true.

if you either change the if statement to if (shown_all == 0) or change how you set the variable shown_all to var shown_all = -current_position + width;, I think you'll see a better result.