从 JSON 中选择

Question

从 JSON 中选择

Joh*_*ith 6 javascript arrays reduce json selection

我最近开始学习 JavaScript，并面临着一个我无法以任何方式完成的任务，每次我得到我需要的错误数据\n有一个包含银行交易数据的对象，我需要进行选择并形成使用filter、map或reduce创建一个新对象：

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我们假设卡上的初始余额 = 0。

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按月输出操作次数最多的TOP 3个月。

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将其形式化为 task_1(arr) 函数，其中 arr 是包含所有月份数据的源数组。

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输出格式：

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[\n    { year: 2019, month: 11, opsCount: 27 },\n    { year: 2019, month: 10, opsCount: 26 },\n    { year: 2019, month: 8, opsCount: 24 }\n]\n

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指定月末的输出统计数据。

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MonthmonthBalance - 按月的自有余额 = 所有\n存款金额减去所有借方金额
montWithdrawal \xe2\x80\x93 提现总额
withdrawalRate \xe2\x80\x93 每月借方总额与存款总额的比例。
\xe2\x80\x93 用户状态排名由以下公式计算：

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如果提款率 < 0.15，则为黄金。

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如果提款率 < 0.3，则为白银。
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在所有其他情况下均为铜牌。
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将其形式化为task_2(year,month,arr)函数，其中year、month是所需的一个月，arr是包含按月所有数据的原始数组。
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输出格式：
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{\ndate: \'2019-01-31\xe2\x80\x99,\nmonthBalance: 3829,\nmonthWithrawal: 33800,\nwithdrawalRate: 0.3133\nrank: \'Bronze\xe2\x80\x99\n}\n
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\n
计算该期间所有月份的任务 2 的统计信息。\n向每个月添加一个字段
\n
\n
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总余额- 累计余额 = 当月自己的余额 + 上个月累计余额的余额。
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输出格式：
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[\n{\ndate: \'2019-01-31\xe2\x80\x99,\nmonthBalance: 3829,\ntotalBalance: 3829,\nmonthWithrawal: 33800,\nwithdrawalRate: 0.3133\nrank: \xe2\x80\x99Bronze\'\n},\n...\n]\n
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将其形式化为 task_3(arr) 函数，其中 arr 是包含数据的源数组。
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JSON数据：
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\r\n
\r\n
[\n { "year": 2019, "month": 1, "day": 1, "type": "replenishment", "amount": 79817 },\n { "year": 2019, "month": 1, "day": 3, "type": "payment", "amount": 11334 },\n { "year": 2019, "month": 1, "day": 5, "type": "withdrawal", "amount": 26700 },\n { "year": 2019, "month": 1, "day": 5, "type": "payment", "amount": 15475 },\n { "year": 2019, "month": 1, "day": 6, "type": "payment", "amount": 4818 },\n { "year": 2019, "month": 1, "day": 6, "type": "payment", "amount": 1893 },\n { "year": 2019, "month": 1, "day": 7, "type": "payment", "amount": 3844 },\n { "year": 2019, "month": 1, "day": 7, "type": "withdrawal", "amount": 3100 },\n { "year": 2019, "month": 1, "day": 7, "type": "payment", "amount": 3230 },\n { "year": 2019, "month": 1, "day": 7, "type": "payment", "amount": 2427 },\n { "year": 2019, "month": 1, "day": 9, "type": "replenishment", "amount": 15835 },\n { "year": 2019, "month": 1, "day": 10, "type": "payment", "amount": 9670 },\n { "year": 2019, "month": 1, "day": 11, "type": "payment", "amount": 582 },\n { "year": 2019, "month": 1, "day": 11, "type": "withdrawal", "amount": 1100 },\n { "year": 2019, "month": 1, "day": 11, "type": "replenishment", "amount": 5971 },\n { "year": 2019, "month": 1, "day": 12, "type": "payment", "amount": 173 },\n { "year": 2019, "month": 1, "day": 14, "type": "withdrawal", "amount": 1500 },\n { "year": 2019, "month": 1, "day": 14, "type": "payment", "amount": 3641 },\n { "year": 2019, "month": 1, "day": 16, "type": "payment", "amount": 4669 },\n { "year": 2019, "month": 1, "day": 18, "type": "payment", "amount": 2460 },\n { "year": 2019, "month": 1, "day": 19, "type": "payment", "amount": 1307 },\n { "year": 2019, "month": 1, "day": 20, "type": "withdrawal", "amount": 1400 },\n { "year": 2019, "month": 1, "day": 21, "type": "payment", "amount": 952 },\n { "year": 2019, "month": 1, "day": 21, "type": "payment", "amount": 561 },\n { "year": 2019, "month": 1, "day": 21, "type": "replenishment", "amount": 6236 },\n { "year": 2019, "month": 1, "day": 22, "type": "payment", "amount": 888 },\n { "year": 2019, "month": 1, "day": 22, "type": "payment", "amount": 2306 },\n { "year": 2019, "month": 2, "day": 1, "type": "replenishment", "amount": 84839 },\n { "year": 2019, "month": 2, "day": 1, "type": "withdrawal", "amount": 27700 },\n { "year": 2019, "month": 2, "day": 1, "type": "payment", "amount": 11145 },\n { "year": 2019, "month": 2, "day": 2, "type": "payment", "amount": 4075 },\n { "year": 2019, "month": 2, "day": 4, "type": "withdrawal", "amount": 10900 },\n { "year": 2019, "month": 2, "day": 6, "type": "payment", "amount": 10537 },\n { "year": 2019, "month": 2, "day": 6, "type": "payment", "amount": 6001 },\n { "year": 2019, "month": 2, "day": 7, "type": "withdrawal", "amount": 7300 },\n { "year": 2019, "month": 2, "day": 10, "type": "withdrawal", "amount": 1500 },\n { "year": 2019, "month": 2, "day": 10, "type": "payment", "amount": 3584 },\n { "year": 2019, "month": 2, "day": 11, "type": "payment", "amount": 701 },\n { "year": 2019, "month": 3, "day": 1, "type": "replenishment", "amount": 84771 },\n { "year": 2019, "month": 3, "day": 3, "type": "withdrawal", "amount": 22700 },\n { "year": 2019, "month": 3, "day": 5, "type": "payment", "amount": 12352 },\n { "year": 2019, "month": 3, "day": 8, "type": "payment", "amount": 2795 },\n { "year": 2019, "month": 3, "day": 11, "type": "withdrawal", "amount": 16600 },\n { "year": 2019, "month": 3, "day": 11, "type": "replenishment", "amount": 4141 },\n { "year": 2019, "month": 3, "day": 11, "type": "payment", "amount": 9854 },\n { "year": 2019, "month": 3, "day": 13, "type": "withdrawal", "amount": 1200 },\n { "year": 2019, "month": 3, "day": 14, "type": "payment", "amount": 11573 },\n { "year": 2019, "month": 3, "day": 14, "type": "payment", "amount": 5138 },\n { "year": 2019, "month": 3, "day": 15, "type": "payment", "amount": 731 },\n { "year": 2019, "month": 3, "day": 17, "type": "payment", "amount": 5053 },\n { "year": 2019, "month": 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"amount": 2758 },\n { "year": 2019, "month": 7, "day": 8, "type": "payment", "amount": 60 },\n { "year": 2019, "month": 7, "day": 10, "type": "withdrawal", "amount": 1100 },\n { "year": 2019, "month": 7, "day": 12, "type": "withdrawal", "amount": 1000 },\n { "year": 2019, "month": 7, "day": 13, "type": "payment", "amount": 151 },\n { "year": 2019, "month": 8, "day": 1, "type": "replenishment", "amount": 85156 },\n { "year": 2019, "month": 8, "day": 1, "type": "payment", "amount": 33978 },\n { "year": 2019, "month": 8, "day": 2, "type": "payment", "amount": 6548 },\n { "year": 2019, "month": 8, "day": 3, "type": "payment", "amount": 5909 },\n { "year": 2019, "month": 8, "day": 6, "type": "payment", "amount": 2326 },\n { "year": 2019, "month": 8, "day": 6, "type": "payment", "amount": 17798 },\n { "year": 2019, "month": 8, "day": 9, "type": "replenishment", "amount": 10770 },\n { "year": 2019, "month": 8, "day": 10, "type": "withdrawal", "amount": 7400 },\n { "year": 2019, "month": 8, "day": 12, "type": "payment", "amount": 6065 },\n { "year": 2019, "month": 8, "day": 14, "type": "withdrawal", "amount": 900 },\n { "year": 2019, "month": 8, "day": 14, "type": "withdrawal", "amount": 1400 },\n { "year": 2019, "month": 8, "day": 14, "type": "payment", "amount": 4673 },\n { "year": 2019, "month": 8, "day": 15, "type": "payment", "amount": 960 },\n { "year": 2019, "month": 8, "day": 15, "type": "payment", "amount": 1085 },\n { "year": 2019, "month": 8, "day": 17, "type": "payment", "amount": 3723 },\n { "year": 2019, "month": 8, "day": 17, "type": "payment", "amount": 2522 },\n { "year": 2019, "month": 8, "day": 19, "type": "replenishment", "amount": 2496 },\n { "year": 2019, "month": 8, "day": 20, "type": "payment", "amount": 876 },\n { "year": 2019, "month": 8, "day": 20, "type": "payment", "amount": 2504 },\n { "year": 2019, "month": 8, "day": 21, "type": "payment", "amount": 826 },\n { "year": 2019, "month": 8, "day": 22, "type": "payment", "amount": 768 },\n { "year": 2019, "month": 8, "day": 23, "type": "withdrawal", "amount": 700 },\n { "year": 2019, "month": 8, "day": 23, "type": "payment", "amount": 190 },\n { "year": 2019, "month": 8, "day": 24, "type": "payment", "amount": 235 },\n { "year": 2019, "month": 9, "day": 1, "type": "replenishment", "amount": 95512 },\n { "year": 2019, "month": 9, "day": 3, "type": "payment", "amount": 26758 },\n { "year": 2019, "month": 9, "day": 3, "type": "replenishment", "amount": 8377 },\n { "year": 2019, "month": 9, "day": 4, "type": "payment", "amount": 30865 },\n { "year": 2019, "month": 9, "day": 4, "type": "withdrawal", "amount": 12800 },\n { "year": 2019, "month": 9, "day": 7, "type": "payment", "amount": 10518 },\n { "year": 2019, "month": 9, "day": 8, "type": "payment", "amount": 11007 },\n { "year": 2019, "month": 9, "day": 10, "type": "payment", "amount": 5613 },\n { "year": 2019, "month": 9, "day": 10, "type": "withdrawal", "amount": 1700 },\n { "year": 2019, "month": 9, "day": 12, "type": "payment", "amount": 2237 },\n { "year": 2019, "month": 9, "day": 14, "type": "payment", "amount": 885 },\n { "year": 2019, "month": 9, "day": 14, "type": "payment", "amount": 977 },\n { "year": 2019, "month": 9, "day": 15, "type": "payment", "amount": 766 },\n { "year": 2019, "month": 9, "day": 17, "type": "payment", "amount": 360 },\n { "year": 2019, "month": 9, "day": 18, "type": "payment", "amount": 116 },\n { "year": 2019, "month": 9, "day": 18, "type": "withdrawal", "amount": 200 },\n { "year": 2019, "month": 9, "day": 19, "type": "payment", "amount": 115 },\n { "year": 2019, "month": 9, "day": 20, "type": "payment", "amount": 50 },\n { "year": 2019, "month": 9, "day": 21, "type": "payment", "amount": 32 },\n { "year": 2019, "month": 10, "day": 1, "type": "replenishment", "amount": 90475 },\n { "year": 2019, "month": 10, "day": 1, "type": "replenishment", "amount": 8845 },\n { "year": 2019, "month": 10, "day": 2, "type": "payment", "amount": 7121 },\n { "year": 2019, "month": 10, "day": 3, "type": "payment", "amount": 27955 },\n { "year": 2019, "month": 10, "day": 3, "type": "payment", "amount": 23079 },\n { "year": 2019, "month": 10, "day": 4, "type": "payment", "amount": 5948 },\n { "year": 2019, "month": 10, "day": 7, "type": "withdrawal", "amount": 4400 },\n { "year": 2019, "month": 10, "day": 8, "type": "payment", "amount": 9677 },\n { "year": 2019, "month": 10, "day": 9, "type": "payment", "amount": 3912 },\n { "year": 2019, "month": 10, "day": 9, "type": "replenishment", "amount": 3870 },\n { "year": 2019, "month": 10, "day": 9, "type": "payment", "amount": 6949 },\n { "year": 2019, "month": 10, "day": 10, "type": "withdrawal", "amount": 3400 },\n { "year": 2019, "month": 10, "day": 10, "type": "replenishment", "amount": 7471 },\n { "year": 2019, "month": 10, "day": 10, "type": "payment", "amount": 5962 },\n { "year": 2019, "month": 10, "day": 10, "type": "payment", "amount": 4990 },\n { "year": 2019, "month": 10, "day": 10, "type": "withdrawal", "amount": 3000 },\n { "year": 2019, "month": 10, "day": 11, "type": "withdrawal", "amount": 200 },\n { "year": 2019, "month": 10, "day": 12, "type": "withdrawal", "amount": 1300 },\n { "year": 2019, "month": 10, "day": 13, "type": "payment", "amount": 986 },\n { "year": 2019, "month": 10, "day": 14, "type": "replenishment", "amount": 4225 },\n { "year": 2019, "month": 10, "day": 15, "type": "withdrawal", "amount": 900 },\n { "year": 2019, "month": 10, "day": 17, "type": "payment", "amount": 864 },\n { "year": 2019, "month": 10, "day": 17, "type": "withdrawal", "amount": 1000 },\n { "year": 2019, "month": 10, "day": 18, "type": "payment", "amount": 801 },\n { "year": 2019, "month": 10, "day": 19, "type": "withdrawal", "amount": 300 },\n { "year": 2019, "month": 10, "day": 20, "type": "payment", "amount": 530 },\n { "year": 2019, "month": 11, "day": 1, "type": "replenishment", "amount": 80285 },\n { "year": 2019, "month": 11, "day": 3, "type": "payment", "amount": 38155 },\n { "year": 2019, "month": 11, "day": 6, "type": "payment", "amount": 10260 },\n { "year": 2019, "month": 11, "day": 9, "type": "payment", "amount": 11013 },\n { "year": 2019, "month": 11, "day": 10, "type": "payment", "amount": 1232 },\n { "year": 2019, "month": 11, "day": 12, "type": "withdrawal", "amount": 5100 },\n { "year": 2019, "month": 11, "day": 12, "type": "payment", "amount": 1192 },\n { "year": 2019, "month": 11, "day": 13, "type": "withdrawal", "amount": 4500 },\n { "year": 2019, "month": 11, "day": 14, "type": "replenishment", "amount": 4304 },\n { "year": 2019, "month": 11, "day": 15, "type": "withdrawal", "amount": 700 },\n { "year": 2019, "month": 11, "day": 15, "type": "replenishment", "amount": 15857 },\n { "year": 2019, "month": 11, "day": 17, "type": "payment", "amount": 9134 },\n { "year": 2019, "month": 11, "day": 19, "type": "payment", "amount": 8090 },\n { "year": 2019, "month": 11, "day": 20, "type": "payment", "amount": 2117 },\n { "year": 2019, "month": 11, "day": 20, "type": "withdrawal", "amount": 2700 },\n { "year": 2019, "month": 11, "day": 21, "type": "withdrawal", "amount": 2200 },\n { "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 258 },\n { "year": 2019, "month": 11, "day": 21, "type": "withdrawal", "amount": 1200 },\n { "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 1966 },\n { "year": 2019, "month": 11, "day": 21, "type": "withdrawal", "amount": 200 },\n { "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 493 },\n { "year": 2019, "month": 11, "day": 21, "type": "payment", "amount
小智 2 解决这些问题这里有提示“GroupBy using reduce” 至于任务1 function task_1(arr) { // Dictionary of Month to Object. const groupedByMonth = arr.reduce(function (acc, currentValue) { let groupKey = currentValue.month; if (!acc[groupKey]) { acc[groupKey] = { year: currentValue.year, month: currentValue.month, opsCount: 0 }; } acc[groupKey].opsCount += 1; // ++ return acc; }, {}); // Sort by opsCount function opsSort(a, b) { return b.opsCount - a.opsCount }; return Object .values(groupedByMonth) // Array of Values .sort(opsSort) .slice(0, 3) // Top 3 } Run Code Online (Sandbox Code Playgroud) 一旦你理解了任务 1 是如何解决的，任务 2 就会变得更简单一些任务 2 的解决方案 function getEndOfMonth(year, month) { const date = new Date(year, month, 0); let monthStr = ""; if (month < 10) { monthStr += "0"; } monthStr += month; return year + "-" + monthStr + "-" + date.getDate(); } function getRank(rate) { if (rate < 0.15) return 'Gold'; if (rate < 0.3) return 'Gold'; return 'Bronze'; } function task_2(arr) { const groupedByMonth = arr.reduce(function (acc, currentValue) { let groupKey = currentValue.month; if (!acc[groupKey]) { acc[groupKey] = { date: getEndOfMonth(currentValue.year, currentValue.month), monthWithrawal: 0, totalDebits: 0, totalDeposits: 0 }; } // Based on type calculate value. if (currentValue.type === "replenishment") { acc[groupKey].totalDeposits += currentValue.amount; } else if (currentValue.type === "payment") { acc[groupKey].totalDebits += currentValue.amount; } else if (currentValue.type === "withdrawal") { acc[groupKey].monthWithrawal += currentValue.amount; } return acc; }, {}); return Object .values(groupedByMonth) // Array of Values .map(function (ele) { const withdrawalRate = ele.monthWithrawal / ele.totalDeposits; return { date: ele.date, monthBalance: ele.totalDeposits - ele.totalDebits - ele.monthWithrawal, monthWithrawal: ele.monthWithrawal, withdrawalRate, rank: getRank(withdrawalRate) }; }); } Run Code Online (Sandbox Code Playgroud) 如果您已经解决了任务 2，那么任务 3 只是将reduce/map 添加到任务2 的解决方案中。 function task_3(arr) { // Assuming that task_2 function is defined. const task2 = task_2(arr); // Can be Solved using reduce. return task2 .map(function (currentValue, index, array) { const tmp = currentValue; tmp.totalBalance = tmp.monthBalance; if (index > 0) { // Not the first element. tmp.totalBalance += array[index - 1].totalBalance; } return tmp; }) } Run Code Online (Sandbox Code Playgroud) 归档时间： 4 年，1 月前查看次数： 144 次最近记录： 4 年，1 月前相关归档是否有JSON的查询语言？ 213 如何将对象解构为已定义的变量？ 69 如何在没有框架的情况下检查DOM是否准备就绪？ 63 如何在 next.js 应用程序中使用谷歌分析？ 46 JSONPath或其他类似XPath的JSON/Javascript实用程序; 或Jquery JSON 14 从位于内存中的JSON加载启动配置 12 我如何解决'Web Compiler在compilerconfig.json中发现错误'？ 11 为什么逐列复制2D数组比C中的逐行复制？ 10 如何在 go gin 中获取从 JSON 发布的文件？ 9 如何从JS中删除字符串中的坏字符？ 8 难疑归档不同浏览器中URL的最大长度是多少？ 4676 为什么这段代码使用随机字符串打印"hello world"？ 1733 Python join:为什么是string.join(list)而不是list.join(string)？ 1669 什么是尾递归？ 1602 SQL Server中的LEFT JOIN与LEFT OUTER JOIN 1514 如何有效地计算JavaScript中对象的键/属性数？ 1452 如何查看Git提交中的更改？ 1364 如何从我的应用程序中在Android的Web浏览器中打开URL？ 1282 适用于PDF文件的MIME媒体类型 1229 同步检查Node.js中是否存在文件/目录 1113

Answer 1

小智 2

解决这些问题这里有提示“GroupBy using reduce”

至于任务1

function task_1(arr) {
    // Dictionary of Month to Object.
    const groupedByMonth = arr.reduce(function (acc, currentValue) {
        let groupKey = currentValue.month;
        if (!acc[groupKey]) {
            acc[groupKey] = {
                year: currentValue.year,
                month: currentValue.month,
                opsCount: 0
            };
        }
        acc[groupKey].opsCount += 1; // ++
        return acc;
    }, {});

    // Sort by opsCount
    function opsSort(a, b) { return b.opsCount - a.opsCount };

    return Object
        .values(groupedByMonth) // Array of Values
        .sort(opsSort)
        .slice(0, 3) // Top 3
}

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一旦你理解了任务 1 是如何解决的，任务 2 就会变得更简单一些

任务 2 的解决方案

function getEndOfMonth(year, month) {
    const date = new Date(year, month, 0);
    let monthStr = "";
    if (month < 10) {
        monthStr += "0";
    }
    monthStr += month;

    return year + "-" + monthStr + "-" + date.getDate();
}

function getRank(rate) {
    if (rate < 0.15)
        return 'Gold';
    if (rate < 0.3)
        return 'Gold';
    return 'Bronze';
}


function task_2(arr) {
    const groupedByMonth = arr.reduce(function (acc, currentValue) {
        let groupKey = currentValue.month;
        if (!acc[groupKey]) {
            acc[groupKey] = {
                date: getEndOfMonth(currentValue.year, currentValue.month),
                monthWithrawal: 0,
                totalDebits: 0,
                totalDeposits: 0
            };
        }

        // Based on type calculate value.
        if (currentValue.type === "replenishment") {
            acc[groupKey].totalDeposits += currentValue.amount;
        } else if (currentValue.type === "payment") {
            acc[groupKey].totalDebits += currentValue.amount;
        } else if (currentValue.type === "withdrawal") {
            acc[groupKey].monthWithrawal += currentValue.amount;
        }

        return acc;
    }, {});

    return Object
        .values(groupedByMonth) // Array of Values
        .map(function (ele) {
            const withdrawalRate = ele.monthWithrawal / ele.totalDeposits;
            return {
                date: ele.date,
                monthBalance: ele.totalDeposits - ele.totalDebits - ele.monthWithrawal,
                monthWithrawal: ele.monthWithrawal,
                withdrawalRate,
                rank: getRank(withdrawalRate)
            };
        });
}

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如果您已经解决了任务 2，那么任务 3 只是将reduce/map 添加到任务2 的解决方案中。

function task_3(arr) {
    // Assuming that task_2 function is defined.
    const task2 = task_2(arr);

    // Can be Solved using reduce.
    return task2
        .map(function (currentValue, index, array) {
            const tmp = currentValue;
            tmp.totalBalance = tmp.monthBalance;
            if (index > 0) { // Not the first element.
                tmp.totalBalance += array[index - 1].totalBalance;
            }
            return tmp;
        })
}

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归档时间：	4 年，1 月前
查看次数：	144 次
最近记录：	4 年，1 月前