<script src="/javascripts/prototype.js" type="text/javascript"></script>
<script src="/javascripts/tooltip.js" type="text/javascript"></script>
<div id='tooltip' style="display:none; margin: 5px; background-color: red">
    Detail infos on product 1....<br />
</div>

<div id='product_1'>
    This is product 1
</div>

<script type="text/javascript">
    var my_tooltip = new Tooltip('product_1', 'tooltip')
</script>

http://ajaxian.com/archives/prototype-based-javascript-tooltip

JavaScript Tooltip libraries number about as many as rounded CSS corner libraries.

Jonathan Weiss thought the ones he saw were "too complicated and bloated, did just too much and most of the time were still not flexible enough with the tooltip. So I decided to create my own library that is based on prototype.js".

Prototype Based JavaScript Tooltip

javascript

JavaScript