Result


maxlength属性は何かとアレなので文字数自体は制限せずに、予め設定した文字数を超過した際に警告文を出すようにする

jQuery

/**
 * Characters limit exceeded warning with a simple jQuery plugin
 * @copyright Copyright 2013-2015 Joan claret
 * @license   MIT
 * @author    Joan Claret Teruel <dpam23 at gmail dot com>
 * Licensed under The MIT License (MIT).
 * Copyright (c) Joan Claret Teruel <dpam23 at gmail dot com>

 */

;(function($, document, window, undefined) {

  'use strict';

  var maxCharWarning = 

    $.fn.maxCharWarning = function() {

        return this.each(function() {
/*カスタムデータ属性等をセッティング*/
          var el                 = $(this),
              maxLength             = el.data('max-length'),
              warningContainerClass   = el.data('max-length-warning-container'),
              warningContainer  = $('.'+warningContainerClass),
              maxLengthMessage      = el.data('max-length-warning')
          ;
          el.keyup(function() {
/*文字数の取得とclassの付与*/
            var length = el.val().length;
            if (length >= maxLength & warningContainer.is(':empty')){
              warningContainer.html(maxLengthMessage);
              el.addClass('input-error');
            }
            else if (length < maxLength & !(warningContainer.is(':empty'))) {
              warningContainer.html('');
              el.removeClass('input-error');
            }
         });
     });
  };
})(window.jQuery || window.$, document, window);

if (typeof module !== 'undefined' && module.exports) {
    module.exports = maxCharWarning;
}
 $(document).ready(function(){
/*セレクタ指定*/
        $('.js-max-char-warning').maxCharWarning();
    });

html

<input
           class ="js-max-char-warning"
           placeholder="なにか書いてね"
           type="text"
           data-max-length-warning="10文字以内でおねがいします"
           data-max-length="10"
           data-max-length-warning-container="name"
    />
    <span class="name"></span><!-- ここにエラーメッセージを表示 -->

via

Maximum Characters limit exceeded warning