让textarea的光标永远停在文档的末尾

<script language="javascript">
function cc(){   
  var e = event.srcElement;   
  var r =e.createTextRange();   
  r.moveStart('character',e.value.length);   
  r.collapse(true);   
  r.select();
}
</script>

<textarea  name=text1 value="123" onfocus="cc()"></textarea>