jQuery实现textarea输入字数限制功能

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>textarea 限制字数</title>
 <style>
  .container{
   position: relative;
   width: 730px;
  }
  .container span{
   position: absolute;
   bottom: 20px;
   right: 30px;
  }
 </style>
</head>
<body>
 <div class="container">
  <textarea name="content" id="content" cols="100" rows="10"></textarea>
  <span>0/10</span>
 </div>
 <script src="http://libs.baidu.com/jquery/2.0.0/jquery.js"></script>
 <script>
  $(function(){
    /**
    * textarea 限制输入字数
    * @param string str 类名或ID
    * @param number num 限制输入的字数
    */
   function limitImport(str,num){
    $(document).on('input propertychange',str,function(){
     var self = $(this);
     var content = self.val();
     if (content.length > num){
      self.val(content.substring(0,num));
     } 
     self.siblings('span').text(self.val().length+'/'+num);
    });
   }

   //用法示例
   limitImport('#content',10);

  })
 </script>
</body>
</html>