Basically this is the question. Which is the difference between these two statements:
language
<script language="javascript" src="_js/calendar/calendar.js"></script>
text/javascript
<script type="text/javascript" src="_js/calendar/calendar.js"></script>
Per the HTML 4.01 Spec:
Language is generally used to indicate the Javascript version that your script requires. Browsers that support the language attribute won’t load or run the script if it doesn’t support it. About the only use would be if you had critical Javascript functions where you needed workarounds for older browsers.