JavaScript: Manipulate the Page

Note the use of event attributes (onclick, onmouseover, onmouseout) as well as a javascript: protocol in an href value.

<div id="cscie75-course"  style="float: left; width: 50%; padding: 10px; margin: 10px; border: thin solid black; font-family: tahoma,arial,helvetica,sans-serif;" >
  <h3>CSCI E-75:  Building Dynamic Websites</h3>
  <p> Harvard Extension School, Spring 2007-2008
    <br/>David J. Malan
    <br/> Monday, 7:35 to 9:35 pm</p>
  <p id="cscie75-description" > Today's websites are increasingly dynamic. Pages are no
    longer static HTML files but instead generated by scripts and database calls. User
    interfaces are more seamless, with technologies like Ajax replacing traditional page
    reloads. This course teaches students how to build dynamic websites with Ajax and with
    Linux, Apache, MySQL, and PHP (LAMP), one of today's most popular frameworks. Students
    learn how to set up domain names with DNS, how to structure pages with XHTML and CSS, how to
    program in JavaScript and PHP, how to configure Apache and MySQL, how to design and query
    databases with SQL, and how to use Ajax with both XML and JSON. The course discusses issues
    of security, scalability, and cross-browser support. Prerequisite: prior programming
    experience in any language. (4 credits) </p>
  </div>
<div style="width: 20%; float: left; margin-left: 2em;" >
  <p><strong>Align Description</strong></p>
      <ul>
        <li><a href="#"  onclick="align('right')"  shape="rect" >right</a></li>
        <li><a href="#"  onclick="align('left')"  shape="rect" >left</a></li>
        <li><a href="#"  onclick="align('justify')"  shape="rect" >justify</a></li>
      </ul> 
  <p><strong>Hide/Show/Toggle Description</strong></p>
      <ul>
        <li><a href="javascript:hidedesc()"  shape="rect" >Hide</a></li>
        <li><a href="#"  onclick="showdesc()"  shape="rect" >Show</a></li>
        <li><a href="#"  onclick="toggledesc()"  shape="rect" >Toggle</a></li>
      </ul> 
  <p><strong>Set background-color</strong></p>
      <ul>
        <li><a href="#"  onclick="backgroundcolor('#f66')"  shape="rect" >red</a></li>
        <li><a href="#"  onclick="backgroundcolor('#6f6')"  shape="rect" >green</a></li>
        <li><a href="#"  onclick="backgroundcolor('#ff6')"  shape="rect" >yellow</a></li>
        <li><a href="#"  onclick="backgroundcolor('#66f')"  shape="rect" >blue</a></li>
        <li><a href="#"  onmouseover="backgroundcolor('#f6f')"  onmouseout="revertcolor()"  shape="rect" >purple</a></li>
      </ul>  
</div>