Method 1 

If Javascript is disabled then an error is displayed... <A HREF="javascript:myFunction()"> Click here for Javascript action!</A>  

Method 2 
If Javascript is disabled then a special page is displayed to warn the user... <A HREF="nojavascripthere.html" 
   onClick="myFunction(); return false">
      Click here for Javascript action!
</A>    

------------------------------------------------------------------
method 1:
<a href="javascript:ShowMovie('/media/showmovie.htm?movie=ds_tutorial.swf',
720, 580);" class="linkTitle">

method 2:
<a href="javascript:void(0);"
onclick="javascript:ShowMovie('/media/showmovie.htm?movie=ds_tutorial.swf',
720, 580);return false;" class="linkTitle">

---
Though this is preferable:
<a href="#" onclick="ShowMovie('/media/showmovie.htm?movie=ds_tutorial.swf',
720, 580);return false;" class="linkTitle">