Q. How do I execute arbitrary javascript?

A. Use the .goto method to call the javascript …
Example html:

<html lang="en-US" xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US">
  <body scroll="no">
    <script type="text/javascript" charset="utf-8">
      function openWin(i){
         alert(i);
      }
    </script>
    <div id="menuLayer1">
      <div id="menuLite1">
        <div id="menuFg1">
          <div id="menuItem1" mmaction="location='javascript:openWin(2);'" zIndex="1">
            <div id="menuItemText1">
              <div id="menuItemShim1">
                <div align="left">
                  just_add_watir
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </body>
</html>

Example watir:

@b.goto('http://justaddwatir.com/watir/test_html/tc_0001_0100/test_0020.html')
@b.div(:id, "menuItem1").flash
@b.goto("javascript:openWin(2)")
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