Call function in comment field to pull cookies or default

This is my goal: I want my comments form fields to be filled in automatically with cookies if they exsist and if they do not I want the fields to default to “Name”, “Email”, “Url” when not focused (onblur).

This is what I’ve done: I’ve included the following atributes to the <input> fields:

onfocus="if(this.value==this.defaultValue)value=''" onblur="if(this.value=='')value=this.defaultValue;"

For the value of the <input>, I’ve put:

value="<?php commentauthor($comment_author,Name) ?>"

And in the header, I've included the following script:


<script>
function commentauthor(cookie,default)
{
if (cookie)
return cookie;
else
return default;
}
</script>


Problems: When I load the page, it says that my function is undefined (fatal error). Did I do something wrong in defining the function?

Also, is there a better way to do this, maybe something built into Word Press that I don’t know about? This should work fine, I think if I can get it to work, but any other suggestions?