对多行文本框限制长度
下面是完整的代码，支持中文，支持粘贴，偶从网上copy的
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>test</title>
<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;
if (controlid == object.id && controlValue != "")
{
result = true;
}
else if (object.value.len() >= length)
{
result = false;
}
if (window.event)
{
window.event.returnValue = result;
return result;
}
}
//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;
}
tempValue=tt;
window.clipboardData.setData("Text", tempValue);
}
window.event.returnValue = true;
}
//-->
</script>
</head>
<body>
<form name="form1" method="post" action="">
<textarea name="textarea" onkeypress="setMaxLength(this,10);" onpaste="limitPaste(this, 10)"></textarea>
</form>
</body>
</html>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><title>test</title><script language=javascript> 
<!-- String.prototype.len=function(){ 
String.prototype.lenreturn 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; if (controlid == object.id && controlValue != "") { result = true; } else if (object.value.len() >= length) { result = false; } if (window.event) { window.event.returnValue = result; return result; } } //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; } tempValue=tt; window.clipboardData.setData("Text", tempValue); } window.event.returnValue = true; } //--> </script> </head><body><form name="form1" method="post" action=""> <textarea name="textarea" onkeypress="setMaxLength(this,10);" onpaste="limitPaste(this, 10)"></textarea></form></body></html>