<html>  

<head runat="server">  

    <title></title>  

    <script type="text/javascript">  

        var maxstrlen = 160;  

        function Q(s) { return document.getElementById(s); }  

        function checkWord(c) {  

            len = maxstrlen;  

            var str = c.value;  

            myLen = getStrleng(str);  

            var wck = Q("wordCheck");  

            if (myLen > len * 2) {  

                c.value = str.substring(0, i + 1);  

            }  

            else {  

                wck.innerHTML = Math.floor((len * 2 - myLen) / 2);  

            }  

        }  

        function getStrleng(str) {  

            myLen = 0;  

            i = 0;  

            for (; (i < str.length) && (myLen <= maxstrlen * 2); i++) {  

                if (str.charCodeAt(i) > 0 && str.charCodeAt(i) < 128)  

                    myLen++;  

                else  

                    myLen += 2;  

            }  

            return myLen;  

        }  

    </script>  

</head>  

<body>  

    <form id="form1" runat="server">  

    <div style="font-size: 16px">  

        控制輸入框字符輸入，計算輸入字符總數(shù),顯示剩余字數(shù);<br>  

        一個英文字符算一個字符，一個中文字符算兩個字符計算。  

    </div>  

    <div>  

        <textarea onkeyup="javascript:checkWord(this);" onmousedown="javascript:checkWord(this);"  

            name="content" style="overflow-y: scroll"></textarea>  

    </div>  

    <div>  

        還可以輸入<span style="font-family: Georgia; font-size: 26px;" id="wordCheck">160</span>個字符  

    </div>  

    </form>  

</body>  

</html>