[thelist] [javaScript] removing values from forms

[Tris]

I'm trying to clear an input box is the default value is not changed..
Here's what I've got and can't figure why it's not working...?
Thoughts...?

  function clearBox(inputName, inputDisplay) {
    if (document.addUser.inputName.value = inputDisplay) {
      document.addUser.inputName.value = '';
    }
  }

And here's a small form

  <form name="addUser" action="' . $_SERVER['PHP_SELF'] . '" method="post">
    <input type="text" name="userName" value="user name"
onclick="javascript: clearBox(\'userName\', \'user name\');"/>
    <input type="text" name="pa55w0rd" value="password"
onclick="javascript: clearBox(\'pa55w0rd\', \'password\');" />
  </form>


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