function limitLength(ele, byteLength) { var newvalue = ele.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 = ele.value.substr(0, size); } else { //当为奇数时 size = (count - 1) / 2 + (byteLength * 1 - count); limitvalue = ele.value.substr(0, size); } ele.value=limitvalue; return; } //用法示例，限制输入byte长度为5 <input type="text" id="ele" onpropertychange="limitLength(this,5)"/>
参考：http://www.weste.net/2007/6-4/08252620525.html
