HTML CODE
<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-1.5.js"></script>
<script>
function countChar(val) {
var len = val.value.length;
if (len >= 500) {
val.value = val.value.substring(0, 500);
} else {
$('#charNum').text(500 - len+ " Characters Left");
}
};
</script>
</head>
<body>
<textarea id="field" onkeyup="countChar(this)"></textarea>
<div id="charNum">500 Characters left</div>
</body>
</html>
DEMO
Check this link http://jsfiddle.net/vetri/p2h976e8/3/
