用js限制用户输入字节个数
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>New Document </title>
<script language="JavaScript">
<!--
function CutStrLength(str,Ilength)
{
var tmp=0;
var len=0;
var okLen=0
for(var i=0;i<Ilength;i++)
{
if(str.charCodeAt(i)>255)
tmp+=2
else
len+=1
okLen+=1
if(tmp+len==Ilength)
{
return (str.substring(0,okLen));
break;
}
if(tmp+len>Ilength)
{
return (str.substring(0,okLen-1)+"");
break;
}
}
}
function checkFieldLength(fieldName,fieldDesc,fieldLength)
{
var str=document.getElementById(fieldName).value;
var theLen=0;
var teststr='';
for(i=0;i<str.length;i++)
{
teststr=str.charAt(i);
if(str.charCodeAt(i)>255)
theLen=theLen+2;
else
theLen=theLen+1;
}
document.getElementById('showMsg').innerText=theLen;
if(theLen>fieldLength)
{
document.getElementById('showMsg').innerText=fieldDesc;
//alert(fieldDesc+" 的字段长度超过规定长度！");
//document.getElementById(fieldName).focus();
document.getElementById(fieldName).value=CutStrLength(str,fieldLength);
return false;
}
else
{
return true;
}
}
//-->
</script>
</head>
<body>
<form method="POST" action="">
<textarea id="testArea" name="testArea" rows="3" cols="22" onkeyup="checkFieldLength('testArea', '超过允许输入的字符个数', 20);"
onchange="checkFieldLength('testArea', '超过允许输入的字符个数', 20);"></textarea>
<div id="testInfo">
已经输入:<span id="showMsg"></span></div>
</form>
</body>
</html>
<html>
<head>
<title>New Document </title>
<script language="JavaScript">
<!--
function CutStrLength(str,Ilength)
{
var tmp=0;
var len=0;
var okLen=0
for(var i=0;i<Ilength;i++)
{
if(str.charCodeAt(i)>255)
tmp+=2
else
len+=1
okLen+=1
if(tmp+len==Ilength)
{
return (str.substring(0,okLen));
break;
}
if(tmp+len>Ilength)
{
return (str.substring(0,okLen-1)+"");
break;
}
}
}
function checkFieldLength(fieldName,fieldDesc,fieldLength)
{
var str=document.getElementById(fieldName).value;
var theLen=0;
var teststr='';
for(i=0;i<str.length;i++)
{
teststr=str.charAt(i);
if(str.charCodeAt(i)>255)
theLen=theLen+2;
else
theLen=theLen+1;
}
document.getElementById('showMsg').innerText=theLen;
if(theLen>fieldLength)
{
document.getElementById('showMsg').innerText=fieldDesc;
//alert(fieldDesc+" 的字段长度超过规定长度！");
//document.getElementById(fieldName).focus();
document.getElementById(fieldName).value=CutStrLength(str,fieldLength);
return false;
}
else
{
return true;
}
}
//-->
</script>
</head>
<body>
<form method="POST" action="">
<textarea id="testArea" name="testArea" rows="3" cols="22" onkeyup="checkFieldLength('testArea', '超过允许输入的字符个数', 20);"
onchange="checkFieldLength('testArea', '超过允许输入的字符个数', 20);"></textarea>
<div id="testInfo">
已经输入:<span id="showMsg"></span></div>
</form>
</body>
</html>
