function textLimitCheck(thisArea, maxLength){
    if (thisArea.value.length > maxLength){
      alert(maxLength + ' 个字限制. \r超出的将自动去除.');
      thisArea.value = thisArea.value.substring(0, maxLength);
      thisArea.focus();
    }
    /*回写span的值，当前填写文字的数量*/
    messageCount.innerText = thisArea.value.length;
  }