下面小编就为大家带来一篇JS判断输入字符串长度实例代码(汉字算两个字符,字母数字算一个)。小编觉得挺不错的，现在就分享给大家，也给大家做个参考。一起跟随小编过来看看吧
js判断输入字符串长度实例代码（汉字算两个字符，字母数字算一个）
文本输入时，由于数据库表字段长度限制会导致提交失败，因此想到了此方法验证。
废话不多说上代码：
<html>
<head>
<title>js判断输入字符串长度（汉字算两个字符，字母数字算一个）</title>
<style type="text/css">
.pbt {
margin-bottom: 10px;
}
.ie6 .pbt .ftid a, .ie7 .pbt .ftid a {
margin-top: 1px;
}
.cl:after {
clear: both;
content: ".";
display: block;
height: 0;
visibility: hidden;
}
</style>
<script type="text/javascript">
//获取字符串长度（汉字算两个字符，字母数字算一个）
function getByteLen(val) {
var len = 0;
for (var i = 0; i < val.length; i++) {
var a = val.charAt(i);
if (a.match(/[^\x00-\xff]/ig) != null) {
len += 2;
}
else {
len += 1;
}
}
return len;
}
// 只要键盘一抬起就验证编辑框中的文字长度，最大字符长度可以根据需要设定
function checkLength(obj) {
var maxChars = 80;//最多字符数
var curr = maxChars - getByteLen(obj.value);
if (curr > 0) {
document.getElementById("checklen").innerHTML = curr.toString();
} else {
document.getElementById("checklen").innerHTML = '0';
document.getElementById("subject").readOnly = true;
}
}
</script>
</head>
<body>
<p class="pbt cl">
<textarea id="subject" maxlength="80" onkeyup="checkLength(this)" accesskey="1" tabindex="11"></textarea>
<span id="subjectchk">还可输入
<strong id="checklen" style="color: #FF0000">80</strong>
个字符
</span>
<span id="postNameRule" class="spn_flag_1" style="display: none"></span>
</p>
</body>
</html>
以上这篇JS判断输入字符串长度实例代码(汉字算两个字符,字母数字算一个)就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持PHP中文网。
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