限制最大文本输入Js代码

园子里一位兄弟写的JS代码（地址：/article/4589871.html）

<script language="javascript">
<!--

String.prototype.len=function(){
return this.replace(/[^\x00-\xff]/g,"**").length;
}

//Set maxlength for multiline TextBox
function setMaxLength(object,length)
{

var result = true;
var controlid = document.selection.createRange().parentElement().id;
var controlValue = document.selection.createRange().text;
var tempString=object.value;

var tt="";
for(var i=0;i<length;i++)
{
if(tt.len()<length)
tt=tempString.substr(0,i+1);
else
break;
}
if(tt.len()>length)
tt=tt.substr(0,tt.length-1);
object.value=tt;

}

//Check maxlength for multiline TextBox when paste
function limitPaste(object,length)
{
var tempLength = 0;
if(document.selection)
{
if(document.selection.createRange().parentElement().id == object.id)
{
tempLength = document.selection.createRange().text.len();
}
}
var tempValue = window.clipboardData.getData("Text");
tempLength = object.value.len() + tempValue.len() - tempLength;

if (tempLength > length)
{
tempLength -= length;
var tt="";
for(var i=0;i<tempValue.len()-tempLength;i++)
{
if(tt.len()<(tempValue.len()-tempLength))
tt=tempValue.substr(0,i+1);
else
break;
}
if(tt.len()<=0)
{
window.event.returnValue=false;

}
else
{
tempValue=tt;
window.clipboardData.setData("Text", tempValue);
window.event.returnValue = true;
}
}

}

function PressLength()
{

if(event.srcElement.type=="text" || event.srcElement.type=="textarea" )
{
if(event.srcElement.length!=null)
setMaxLength(event.srcElement,event.srcElement.length);

}
}

function LimitLength()
{

if(event.srcElement.type=="text" || event.srcElement.type=="textarea" )
{
if(event.srcElement.length!=null)
limitPaste(event.srcElement,event.srcElement.length);
}
}
document.documentElement.attachEvent('onkeyup', PressLength);
document.documentElement.attachEvent('onpaste', LimitLength);

//-->
</script>

但是这个毕竟是在客户端的，本着“客户不信任”的原则，在服务器端得验证还是少不了的。

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }