JS: Buttons that add text to a textarea

Sorta like how the smilies work on Vbf. You click it and ":)" appears in the textarea. How is this done?

window.textarea.innertext = ':D'

you might need to use window.document instead im not to sure

You can also do it something like this:

Code:

---

<script type="text/javascript"><!--
function insertSmilie(smilie) {
  document.forms['feedback'].comments.value = smilie;
  return false;
}
//--></script>

<form id="feedback">
  <textarea id="comments"></textarea>
</form>

<a href="#" onclick="return insertSmilie(':)');">:)</a>

---