Question

I have a fixed position element on a page. I want that element contained within a certain div tag of an ID or Class that I assign. Here is a fiddle with an example. In the example the floating bar should not go above or below the black box.

I do not mind using jQuery to change the functions, I am using v. 1.8.3.

Here as a site that shows an example of what I am after. Look on the left side.

Here is the code for the example:

HTML

<div class="wrapper">
<div class="top">
    <p>&nbsp;</p>
</div>
<div class="container">
<p>Floating Bar Should not go above this point.</p>

<p>&nbsp;</p>

</div>
<p>Floating Bar Should not go below this point.</p>
    <p>&nbsp;</p>

</div>

    <div class="add-this-container" >
    <!-- AddThis Button BEGIN -->
<div class="addthis_toolbox addthis_floating_style addthis_counter_style">
<a class="addthis_button_facebook_like" fb:like:layout="box_count"></a>
<a class="addthis_button_tweet" tw:count="vertical"></a>
<a class="addthis_button_google_plusone" g:plusone:size="tall"></a>
<a class="addthis_counter"></a>
</div>
<script type="text/javascript" src="//s7.addthis.com/js/300/addthis_widget.js">   </script>
<!-- AddThis Button END -->
</div>

CSS

.wrapper{
    height:1500px;
    background: #808080;
    width: 300px;
}
.container{
    background: #111;
    height: 600px;
}
.top{
    height: 400px;
    background: #7e0000;
}
.add-this-container{
position: absolute;
    left: 350px;
    top: 250px;
}
.addthis_floating_style{
    background: #ccc;
 }
p{
    color: white;
}

Answer 1

I added a few Id’s to your html to get their positions (header and footer)

<div class="wrapper">
    <div class="top">
        <p>&nbsp;</p>
    </div>
    <div class="container">
    <p id="header">Floating Bar Should not go above this point.</p>

    <p>&nbsp;</p>

    </div>
    <p id="footer">Floating Bar Should not go below this point.</p>
        <p>&nbsp;</p>

</div>

<div class="add-this-container" >
        <!-- AddThis Button BEGIN -->
<div class="addthis_toolbox addthis_floating_style addthis_counter_style">
<a class="addthis_button_facebook_like" fb:like:layout="box_count"></a>
<a class="addthis_button_tweet" tw:count="vertical"></a>
<a class="addthis_button_google_plusone" g:plusone:size="tall"></a>
<a class="addthis_counter"></a>
</div>
<script type="text/javascript" src="//s7.addthis.com/js/300/addthis_widget.js"></script>
<!-- AddThis Button END -->
</div>

This little script will stop the floating div once it reaches the header or footer breakoff points.
I made the script to be bit ‘on the nose’ tho help you understnd what it does and when.
It can be made a bit prettier, parhaps animate the position change.

$(function(){

    //Scroll event, sets position on scroll
    $(document).scroll(function() { 
        position();        
    });

    // Set initial position on document ready
    position();
});


function position()
{
            //Collect positions
        var floaterHeight = $('.addthis_floating_style').height();
        var headerBreakoff = $('#header').offset().top + $('#header').height();
        var footerBreakoff = $('#footer').offset().top;

        var newTop = $(document).scrollTop() + 20; // this will be position when between header and footer        

        if(newTop <= headerBreakoff) // Above header
        {        
            newTop = headerBreakoff;
        }
        else if(newTop + floaterHeight >= footerBreakoff) // Below footer
        {
            newTop =  footerBreakoff - floaterHeight;
        }

        //Set position
        $(".addthis_floating_style").offset({ top: newTop});
}

Here is the fiddle

http://jsfiddle.net/urbanbjorkman/BJ6EP/