따로 설명은 하지 않겠습니다.
요 기능은 글 작성시 눈으로 바로바로 몇 글자 입력이 가능한지 확인이 됨니다.
다음 번에는 거꾸로 입력하는 글자 수를 나타나는 것을 올려보도록 하겠습니다.



<script language="javascript">
  function mBoxreset(){
           document.write.msglen.value = '80';
           document.write.memo.value = '';
   }

   function CheckLen(form){
          var msglen;
          var maxlen;
          var l;
          var tmpstr;

          msglen = form.maxmsglen.value;
          maxlen = msglen;
          l = form.memo.value.length;
          tmpstr = "";

          if (l == 0) document.write.msglen.value = msglen;
          else
                    for(k=0;k<l;k++){
                              t = form.memo.value.charAt(k);
                              if (escape(t).length > 4) msglen -= 2;
                              else msglen--;
            
                              if(msglen < 0){
                                        alert(maxlen + " 바이트 안에서 입력할 수 있습니다.");
                                        document.write.memo.value = tmpstr;
                              }else{
                                        document.write.msglen.value = msglen;
                                        tmpstr += t;
                                        document.write.memo.focus();
                              }
                    }
   }
</script>

<form name="write" method="post" action="">
<input type="hidden" name="maxmsglen" value="80">
<input type=="Text" name="msglen" size="2" value='80' style="border:1 solid gray; font-size:8pt; background-color:#ffffff;">
<textarea rows="7" cols="16" name="memo" onChange="CheckLen(this.form)" onKeyUp="CheckLen(this.form)"></textarea>
</form>