progBarColor

HTML

<textarea></textarea>
<span id="characters">255 left</span>

<br>
<progress id="myProgress" value="0" max="255">
</progress>

JavaScript

$('textarea').keyup(updateCount);
$('textarea').keydown(updateCount);

function updateCount() {
	 var max = 255;
    var cs = $(this).val().length;
    document.getElementById("characters").innerHTML= max-cs + " left..";
    document.getElementById("myProgress").value = cs;
    if (event.which < 0x20) {
        return;
      }
    if (cs == max) {
        event.preventDefault();
        // make the color of progress bar red here!! 
      }     
      
}