<div class="wrap">

         <textarea></textarea>

         <div class="miss"></div>

     </div>

 $('textarea').on('input propertychange', function() {

         $('.miss').html($(this).val().length + "~"+$(this).val());

     });

 var txt = document.querySelector("textarea"),

         msg = document.querySelector(".miss");

     //不兼容IE8 以下

     txt.addEventListener("input",function  () {

         msg.innerHTML = this.value + "~"+this.value.length;

     },false)