Fujihai/index.html

## index.html
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
</head>

<body>
    <script>
        // 基础变量
        var encodeMapChar = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-';

        // 函数调用测试
        console.log(`days2dateStr(7400): `, days2dateStr(7400));
        console.log(`getDays("20200410"): `, getDays("20200410"));
        console.log(`encodeDateStr("20200301", "20200307", "20200308", "20200315")`,
            encodeDateStr("20200301", "20200307", "20200308", "20200315"));
        console.log(`decodeDateStr("sNhPbsP1Pj"):`, decodeDateStr("sNhPbsP1Pj"));
        console.log(`string10to64(138870): `, string10to64(138870));

        /**
        * 64 进制数转 10 进制
        */
        function string64to10(numberCode) {
            var radix = encodeMapChar.length;
            numberCode = String(numberCode);
            var len = numberCode.length,
                i = 0,
                originNumber = 0;
            while (i < len) {
                originNumber += Math.pow(radix, i++) * encodeMapChar.indexOf(numberCode.charAt(len - i) || 0);
            }
            return originNumber;
        }

        /**
        * 10 进制数转换成 64 进制
        */
        function string10to64(number) {
            var radix = encodeMapChar.length,
                qutient = +number,
                arr = [];
            do {
                var mod = qutient % radix;
                qutient = (qutient - mod) / radix;
                arr.unshift(encodeMapChar[mod]);
            } while (qutient);
            return arr.join('');
        }
        /**
        *  10 进制数转换成 64 进制数，并设置最小长度
        *  若转换数值长度小于 len 长度，高位补 0，否则不做处理
        */
        function encodeNlen(intNum, len) {
            var tmp = string10to64(intNum);
            var curLen = tmp.length;
            for (var i = curLen; i < len; i++) {
                tmp = '0' + tmp;
            }
            return tmp;
        }

        /**
        * 返回距离 2000 年 1 月 1 日，天数为 days 的当前日期，格式为 YYYYMMDD 类型
        * 比如：20200301
        */
        function days2dateStr(days) {
            var baseDate = new Date(2000, 0, 1, 0, 0, 0, 0);
            var resDate = new Date(baseDate.getTime() + days * 24 * 60 * 60 * 1000);
            var year = resDate.getFullYear();
            var month = resDate.getMonth() + 1;
            var day = resDate.getDate();
            month = month < 10 ? '0' + month : month;
            day = day < 10 ? '0' + day : day;
            return `${year}${month}${day};
        }

        /**
        * 计算当前日期与 2000 年 1 月 1 日之间相差的天数
        * 参数日期格式： 20200410
        */
        function getDays(curDateStr) {
            var baseDate = new Date(2000, 0, 1, 0, 0, 0);
            var year = parseInt(curDateStr.substr(0, 4));
            var month = parseInt(curDateStr.substr(4, 2));
            var day = parseInt(curDateStr.substr(6, 2));
            month = month > 0 ? (month - 1) : 0;
            var curDate = new Date(year, month, day, 0, 0, 0);
            var days = (curDate.getTime() - baseDate.getTime()) / (24 * 60 * 60 * 1000);
            return days;
        }
        /**
        * 日期字符串编码
        */
        function encodeDateStr(oneDt, twoDt, threeDt, fourDt) {
            var oneDtDays = getDays(oneDt);
            var twoDtDays = getDays(twoDt);
            var threeDtDays = getDays(threeDt);
            var fourDtDays = getDays(fourDt);
            // 高 16 位存放 oneDtDays， 低 16 位存放 twoDtDays
            var left = (oneDtDays << 16) + twoDtDays;
            var right = (threeDtDays << 16) + fourDtDays;
            return encodeNlen(left, 5) + encodeNlen(right, 5);
        }

        function decodeDateStr(encodeStr) {
            var left = string64to10(encodeStr.substring(0, 5));
            var right = string64to10(encodeStr.substring(5, 10));
            var oneDt = left >> 16;
            var twoDt = left & 0xFFFF;
            var threeDt = right >> 16;
            var fourDt = right & 0xFFFF;
            return [this.days2dateStr(oneDt), this.days2dateStr(twoDt),
                    this.days2dateStr(threeDt), this.days2dateStr(fourDt)];
        }
    </script>
</body>

</html>
	<!DOCTYPE html>
	<html lang="en">

	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	</head>

	<body>
	<script>
	// 基础变量
	var encodeMapChar = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-';

	// 函数调用测试
	console.log(`days2dateStr(7400): `, days2dateStr(7400));
	console.log(`getDays("20200410"): `, getDays("20200410"));
	console.log(`encodeDateStr("20200301", "20200307", "20200308", "20200315")`,
	encodeDateStr("20200301", "20200307", "20200308", "20200315"));
	console.log(`decodeDateStr("sNhPbsP1Pj"):`, decodeDateStr("sNhPbsP1Pj"));
	console.log(`string10to64(138870): `, string10to64(138870));

	/**
	* 64 进制数转 10 进制
	*/
	function string64to10(numberCode) {
	var radix = encodeMapChar.length;
	numberCode = String(numberCode);
	var len = numberCode.length,
	i = 0,
	originNumber = 0;
	while (i < len) {
	originNumber += Math.pow(radix, i++) * encodeMapChar.indexOf(numberCode.charAt(len - i) \|\| 0);
	}
	return originNumber;
	}

	/**
	* 10 进制数转换成 64 进制
	*/
	function string10to64(number) {
	var radix = encodeMapChar.length,
	qutient = +number,
	arr = [];
	do {
	var mod = qutient % radix;
	qutient = (qutient - mod) / radix;
	arr.unshift(encodeMapChar[mod]);
	} while (qutient);
	return arr.join('');
	}
	/**
	* 10 进制数转换成 64 进制数，并设置最小长度
	* 若转换数值长度小于 len 长度，高位补 0，否则不做处理
	*/
	function encodeNlen(intNum, len) {
	var tmp = string10to64(intNum);
	var curLen = tmp.length;
	for (var i = curLen; i < len; i++) {
	tmp = '0' + tmp;
	}
	return tmp;
	}

	/**
	* 返回距离 2000 年 1 月 1 日，天数为 days 的当前日期，格式为 YYYYMMDD 类型
	* 比如：20200301
	*/
	function days2dateStr(days) {
	var baseDate = new Date(2000, 0, 1, 0, 0, 0, 0);
	var resDate = new Date(baseDate.getTime() + days * 24 * 60 * 60 * 1000);
	var year = resDate.getFullYear();
	var month = resDate.getMonth() + 1;
	var day = resDate.getDate();
	month = month < 10 ? '0' + month : month;
	day = day < 10 ? '0' + day : day;
	return `${year}${month}${day};
	}

	/**
	* 计算当前日期与 2000 年 1 月 1 日之间相差的天数
	* 参数日期格式： 20200410
	*/
	function getDays(curDateStr) {
	var baseDate = new Date(2000, 0, 1, 0, 0, 0);
	var year = parseInt(curDateStr.substr(0, 4));
	var month = parseInt(curDateStr.substr(4, 2));
	var day = parseInt(curDateStr.substr(6, 2));
	month = month > 0 ? (month - 1) : 0;
	var curDate = new Date(year, month, day, 0, 0, 0);
	var days = (curDate.getTime() - baseDate.getTime()) / (24 * 60 * 60 * 1000);
	return days;
	}
	/**
	* 日期字符串编码
	*/
	function encodeDateStr(oneDt, twoDt, threeDt, fourDt) {
	var oneDtDays = getDays(oneDt);
	var twoDtDays = getDays(twoDt);
	var threeDtDays = getDays(threeDt);
	var fourDtDays = getDays(fourDt);
	// 高 16 位存放 oneDtDays，低 16 位存放 twoDtDays
	var left = (oneDtDays << 16) + twoDtDays;
	var right = (threeDtDays << 16) + fourDtDays;
	return encodeNlen(left, 5) + encodeNlen(right, 5);
	}

	function decodeDateStr(encodeStr) {
	var left = string64to10(encodeStr.substring(0, 5));
	var right = string64to10(encodeStr.substring(5, 10));
	var oneDt = left >> 16;
	var twoDt = left & 0xFFFF;
	var threeDt = right >> 16;
	var fourDt = right & 0xFFFF;
	return [this.days2dateStr(oneDt), this.days2dateStr(twoDt),
	this.days2dateStr(threeDt), this.days2dateStr(fourDt)];
	}
	</script>
	</body>

	</html>