JS简单限制textarea内输入字符数量的方法

<script> function getStringUTFLength(str) {  var value = str.replace(/[/u4e00-/u9fa5]/g," "); //将汉字替换为两个空格 return value.length; } function leftUTFString(str,len) {  if(getStringUTFLength(str)<=len) {   return str;  } var value = str.substring(0,len);  while(getStringUTFLength(value)>len) {   value = value.substring(0,value.length-1);  }  return value; } function count() {  var len=255; var value = document.getElementById("licenseother").value;  if(getStringUTFLength(value)>=len) {    document.getElementById("licenseother").value = leftUTFString(document.getElementById("licenseother").value,len);  }  document.getElementById("result").value = len-getStringUTFLength(document.getElementById("licenseother").value); } </script> <table width="100%">  <tr>  <td>    <textarea cols=100 rows=4 id="licenseother" onkeypress="count()" onkeyup="count()" onblur="count();" onChange="count();"></textarea>   </td> </tr>  <tr>  <td>    本输入框限制输入255个字符(汉字计算为2个字符)  剩余字符数：   <input readonly type="text" size="3" id="result" value="255">   </td> </tr> </table>