javascript客户端规定最多输入的字符串长度

<script language="javascript">

<!--

function textCounter(field,maxlimit)

{

var str="";

str=field.value;

str=str.replace(/[^\x00-\xff]/g,"**");

if (str.length > maxlimit)

{

// field.value = field.value.substring(0, maxlimit);

field.value=getByteOfNum(field.value,maxlimit);

}

}

function getByteOfNum(val, num)

{

var ch,bytenum=0;

var rs = "";

var pt = /[^\x00-\xff]/;

for (var i=0; i < num; i++)

{

ch = val.substr(i, 1);

if (ch.match(pt))

{

bytenum += 2;

if (bytenum > num)

{

return rs;

}

}else

{

bytenum += 1;

}

rs += ch;

if (bytenum == num)

{

return rs;

}

}

return rs;

}

//-->

aspx中调用的代码：

<asp:textbox id="txtAttendOuter" runat="server" onkeydown="textCounter(this.form.txtAttendOuter,100);"

onkeyup="textCounter(this.form.txtAttendOuter,100);" Width="145px"></asp:textbox>