jquery之input输入框限制输入字符数及汉字数

直接上代码

JSP页面示例：

<%--20为限制的字符数，相当于2倍的汉字数--%>

 Jquery代码

function checkField(value, byteLength, attribute) {
    	// value是input框的值,byteLength是需求限制的字符，attribute是input的id名
    	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(
    	"最大输入" +
    	byteLength +
    	"个字节（相当于" +
    	byteLength / 2 +
    	"个汉字）！"
    	);
    	document.getElementById(attribute).value = limitvalue;
    	return;
    	}