JET

JSES - JavaScript Event Sheets
To activate the JSES functionality you just have to put in the following:

<html>
  <head>
    <@jet.js_es/>
    <@jet.linkrel_es url="<your test file>"/>
  </head>
...

in your test file you can define the javascript events like css:

.img { 
    background-color: red; onmouseover: alertImage;
}

You can define the function alerImage directly in your site or in a js file:

function alertImage(e){
    alert('Mouse moved over an image!' + e);
}