Textarea s obmedzeným počtom znakov

<SCRIPT LANGUAGE="JavaScript">
function CountLeft(field, count, max) {
if (field.value.length > max) field.value = field.value.substring(0, max); else
count.value = max - field.value.length; }
</script>

<form name=sample action="">
  <textarea rows="10" cols="40" name="text"
      onKeyDown="CountLeft(this.form.text,this.form.left,50);"
      onKeyUp="CountLeft(this.form.text,this.form.left,50);">
  </textarea>
  <br>
  Počet zostávajúcich znakov:
  <input readonly type="text" name="left" size=3 maxlength=3 value="50">
</form>