rangy

gistfile1.js

<script type="text/javascript">

  function clean(id) {
    setTimeout('clean2("'+id+'")', 1)
  }
  function clean2(id) {
    el=document.getElementById(id)
    var savedSel = rangy.saveSelection();

    el.innerHTML = el.innerHTML.replace(/(<([^>]+)>)/ig,"");
    el.innerHTML = el.innerHTML.replace(/([0-9])/ig,"<font color='red'>$1</font>");

    rangy.restoreSelection(savedSel);

    return false;
  }
</script>

<div contenteditable="true" id="pad" onkeyup="clean('pad')"></div>