limit.js

jQuery(document).ready(function()
{
    jQuery("#order_comments").attr('maxlength','140'); // make sure to change the 140 number here to match the number after remaining below
	  countdownCharacters();
    jQuery('#order_comments').change(updateCountdown);
    jQuery('#order_comments').keyup(updateCountdown);
});
function countdownCharacters() {
    // 140 is the max message length
    var remaining = 140 - jQuery('#order_comments').val().length;
    jQuery('.order_countdown').html('<label for="order_comments">Order Notes</label>' + remaining + ' characters remaining.');
}