<input name="textfield" type="text" maxlength="22" />设置文本框的maxlength="22"
<input name="textfield" type="text" maxlength="22" />设置文本框的maxlength="22"
<input name="textfield" type="text" maxlength="22" />设置文本框的maxlength="22"
<input name="textfield" type="text" maxlength="22" />设置文本框的maxlength="22"
{
var con = document.getElementById(controlName);
var str = con.value;
str = escape(str);
for (i = 0,len=0; i < str.length; i++, len++) {
if (str.charAt(i) == "%") {
if (str.charAt(++i) == "u") {
i += 3;
len++;
}
i++;
}
}
if(len > maxlength){
alert(Message);
con.focus();
return true
}
return false
}
这个比较好，上面的虽然可以但是判断不了汉字双字节的。
这样就行了.汉字也算一个字符
var LastCount=0;
function CountStrByte(Message,Used)
{
var ByteCount=0;
var StrValue=Message.value;
var StrLength=Message.value.length;
var MaxValue=100;
if(LastCount!=StrLength)
{
for(i=0;i <StrLength;i++)
{
ByteCount=ByteCount+1;
if(ByteCount>MaxValue)
{
Message.value=StrValue.substring(0,i);
ByteCount=MaxValue;
break;
}
}
Used.innerHTML=ByteCount;
}
else
Used.innerHTML=ByteCount;
}
</script> <body>
<br>
<br>
<textarea name="a" onKeyDown="CountStrByte(a,b);" onkeyup ="CountStrByte(this,document.getElementById('b'));"></textarea>
已输入 <span id=b>0</span>个字(最多可以输入100个字符！)
<head>
<title>Javascript判断字符串长度</title>
</head>
<body>
<script type="text/javascript">
function getlengthB(str)
{
return str.replace(/[^\x00-\xff]/g,"**").length;
}
</script>
<input type="text" maxlength="10" value="" onblur="alert(getlengthB(this.value))" />
<body>
</html>
var newvalue = value.replace(/[^\x00-\xff]/g, "**");
var length = newvalue.length;
//当填写的字节数小于设置的字节数
if (length * 1 <=byteLength * 1){
return;
}
var limitDate = newvalue.substr(0, byteLength);
var count = 0;
var limitvalue = "";
for (var i = 0; i < limitDate.length; i++) {
var flat = limitDate.substr(i, 1);
if (flat == "*") {
count++;
}
}
var size = 0;
var istar = newvalue.substr(byteLength * 1 - 1, 1);//校验点是否为“×”
//if 基点是×; 判断在基点内有×为偶数还是奇数
if (count % 2 == 0) {
//当为偶数时
size = count / 2 + (byteLength * 1 - count);
limitvalue = value.substr(0, size);
} else {
//当为奇数时
size = (count - 1) / 2 + (byteLength * 1 - count);
limitvalue = value.substr(0, size);
}
alert(title + "最大输入" + byteLength + "个字节（相当于"+byteLength /2+"个汉字）！");
document.getElementById(attribute).value = limitvalue;
return;
} <script type="text/javascript" src="limitlength.js"></script>
<input type="text" name="uid" id="uid" onkeyup="limitLength(value,10,'语义说明:','uid'); " />