form中限制文本字节数js代码_表单特效

/*
value: 值；
byteLength：数据库字节长度
title：字段中文名称
attribute：属性名称
使用方法说明：

添加 （1） onkeyup="limitLength(this.value,100,'名称','name')"
(2) id="name" 或【struts标签】styleId="name"
注意：id名称和 attribute属性名称要一样

例子：<br><br> 或 <br><br><input type="text" name="explain" id="explain" onkeyup="limitLength(value,5,'语义说明','explain')"><br><br>*/ <br><br><br><br>function limitLength(value, byteLength, title, attribute) { <br> var newvalue = value.replace(/[^\x00-\xff]/g, "**"); <br> var length = newvalue.length; <br><br> //当填写的字节数小于设置的字节数 <br> if (length * 1 return; <br> } <br> var limitDate = newvalue.substr(0, byteLength); <br> var count = 0; <br> var limitvalue = ""; <br> for (var i = 0; i var flat = limitDate.substr(i, 1); <br> if (flat == "*") { <br> count++; <br> } <br> } <br> var size = 0; <br> var istar = newvalue.substr(byteLength * 1 - 1, 1);//校验点是否为“×” <br><br> //if 基点是×; 判断在基点内有×为偶数还是奇数 <br> if (count % 2 == 0) { <br> //当为偶数时 <br> size = count / 2 + (byteLength * 1 - count); <br> limitvalue = value.substr(0, size); <br> } else { <br> //当为奇数时 <br> size = (count - 1) / 2 + (byteLength * 1 - count); <br> limitvalue = value.substr(0, size); <br> } <br> alert(title + "最大输入" + byteLength + "个字节（相当于"+byteLength /2+"个汉字）！"); <br> document.getElementById(attribute).value = limitvalue; <br> return; <br>}