最近開始學習JavaScript，遇到了一個無論如何都無法完成的任務，每次得到我需要的錯誤資料有一個包含銀行交易資料的物件，我需要進行選擇并形成一個新的使用過濾器、映射或縮減的物件：
我們假設卡上的初始余額 = 0。
- 按月輸出操作次數最多的前3個月。
將其形式化為 task_1(arr) 函式，其中 arr 是包含所有月份資料的源陣列。
輸出格式：
[
{ year: 2019, month: 11, opsCount: 27 },
{ year: 2019, month: 10, opsCount: 26 },
{ year: 2019, month: 8, opsCount: 24 }
]
- 指定月末的輸出統計資訊。
- monthmonthBalance -按月計算的自己的余額 = 所有存款金額減去所有借項金額
- montWithdrawal – 提款總額
- 提款率– 每月存款總額中借方總額的份額。
- rank – 由公式計算的用戶狀態：
如果提款率 < 0.15，則為黃金。
如果提款率 < 0.3，則為白銀。
在所有其他情況下為青銅。
將其形式化為 task_2(year, month, arr) 函式，其中 year, month 是所需的一個月，arr 是原始陣列，其中包含按月列出的所有資料。
輸出格式：
{
date: '2019-01-31’,
monthBalance: 3829,
monthWithrawal: 33800,
withdrawalRate: 0.3133
rank: 'Bronze’
}
- 計算任務 2 中所有月份的統計資料。為每個月添加一個欄位
- totalBalance - 累計余額 = 當月自己的余額 上個月累計余額的余額。
輸出格式：
[
{
date: '2019-01-31’,
monthBalance: 3829,
totalBalance: 3829,
monthWithrawal: 33800,
withdrawalRate: 0.3133
rank: ’Bronze'
},
...
]
將其形式化為 task_3(arr) 函式，其中 arr 是包含資料的源陣列。
帶有資料的JSON ：
[
{ "year": 2019, "month": 1, "day": 1, "type": "replenishment", "amount": 79817 },
{ "year": 2019, "month": 1, "day": 3, "type": "payment", "amount": 11334 },
{ "year": 2019, "month": 1, "day": 5, "type": "withdrawal", "amount": 26700 },
{ "year": 2019, "month": 1, "day": 5, "type": "payment", "amount": 15475 },
{ "year": 2019, "month": 1, "day": 6, "type": "payment", "amount": 4818 },
{ "year": 2019, "month": 1, "day": 6, "type": "payment", "amount": 1893 },
{ "year": 2019, "month": 1, "day": 7, "type": "payment", "amount": 3844 },
{ "year": 2019, "month": 1, "day": 7, "type": "withdrawal", "amount": 3100 },
{ "year": 2019, "month": 1, "day": 7, "type": "payment", "amount": 3230 },
{ "year": 2019, "month": 1, "day": 7, "type": "payment", "amount": 2427 },
{ "year": 2019, "month": 1, "day": 9, "type": "replenishment", "amount": 15835 },
{ "year": 2019, "month": 1, "day": 10, "type": "payment", "amount": 9670 },
{ "year": 2019, "month": 1, "day": 11, "type": "payment", "amount": 582 },
{ "year": 2019, "month": 1, "day": 11, "type": "withdrawal", "amount": 1100 },
{ "year": 2019, "month": 1, "day": 11, "type": "replenishment", "amount": 5971 },
{ "year": 2019, "month": 1, "day": 12, "type": "payment", "amount": 173 },
{ "year": 2019, "month": 1, "day": 14, "type": "withdrawal", "amount": 1500 },
{ "year": 2019, "month": 1, "day": 14, "type": "payment", "amount": 3641 },
{ "year": 2019, "month": 1, "day": 16, "type": "payment", "amount": 4669 },
{ "year": 2019, "month": 1, "day": 18, "type": "payment", "amount": 2460 },
{ "year": 2019, "month": 1, "day": 19, "type": "payment", "amount": 1307 },
{ "year": 2019, "month": 1, "day": 20, "type": "withdrawal", "amount": 1400 },
{ "year": 2019, "month": 1, "day": 21, "type": "payment", "amount": 952 },
{ "year": 2019, "month": 1, "day": 21, "type": "payment", "amount": 561 },
{ "year": 2019, "month": 1, "day": 21, "type": "replenishment", "amount": 6236 },
{ "year": 2019, "month": 1, "day": 22, "type": "payment", "amount": 888 },
{ "year": 2019, "month": 1, "day": 22, "type": "payment", "amount": 2306 },
{ "year": 2019, "month": 2, "day": 1, "type": "replenishment", "amount": 84839 },
{ "year": 2019, "month": 2, "day": 1, "type": "withdrawal", "amount": 27700 },
{ "year": 2019, "month": 2, "day": 1, "type": "payment", "amount": 11145 },
{ "year": 2019, "month": 2, "day": 2, "type": "payment", "amount": 4075 },
{ "year": 2019, "month": 2, "day": 4, "type": "withdrawal", "amount": 10900 },
{ "year": 2019, "month": 2, "day": 6, "type": "payment", "amount": 10537 },
{ "year": 2019, "month": 2, "day": 6, "type": "payment", "amount": 6001 },
{ "year": 2019, "month": 2, "day": 7, "type": "withdrawal", "amount": 7300 },
{ "year": 2019, "month": 2, "day": 10, "type": "withdrawal", "amount": 1500 },
{ "year": 2019, "month": 2, "day": 10, "type": "payment", "amount": 3584 },
{ "year": 2019, "month": 2, "day": 11, "type": "payment", "amount": 701 },
{ "year": 2019, "month": 3, "day": 1, "type": "replenishment", "amount": 84771 },
{ "year": 2019, "month": 3, "day": 3, "type": "withdrawal", "amount": 22700 },
{ "year": 2019, "month": 3, "day": 5, "type": "payment", "amount": 12352 },
{ "year": 2019, "month": 3, "day": 8, "type": "payment", "amount": 2795 },
{ "year": 2019, "month": 3, "day": 11, "type": "withdrawal", "amount": 16600 },
{ "year": 2019, "month": 3, "day": 11, "type": "replenishment", "amount": 4141 },
{ "year": 2019, "month": 3, "day": 11, "type": "payment", "amount": 9854 },
{ "year": 2019, "month": 3, "day": 13, "type": "withdrawal", "amount": 1200 },
{ "year": 2019, "month": 3, "day": 14, "type": "payment", "amount": 11573 },
{ "year": 2019, "month": 3, "day": 14, "type": "payment", "amount": 5138 },
{ "year": 2019, "month": 3, "day": 15, "type": "payment", "amount": 731 },
{ "year": 2019, "month": 3, "day": 17, "type": "payment", "amount": 5053 },
{ "year": 2019, "month": 3, "day": 19, "type": "withdrawal", "amount": 400 },
{ "year": 2019, "month": 3, "day": 20, "type": "payment", "amount": 1745 },
{ "year": 2019, "month": 3, "day": 20, "type": "payment", "amount": 602 },
{ "year": 2019, "month": 3, "day": 21, "type": "payment", "amount": 178 },
{ "year": 2019, "month": 3, "day": 22, "type": "payment", "amount": 353 },
{ "year": 2019, "month": 3, "day": 23, "type": "payment", "amount": 837 },
{ "year": 2019, "month": 3, "day": 23, "type": "payment", "amount": 330 },
{ "year": 2019, "month": 3, "day": 23, "type": "payment", "amount": 799 },
{ "year": 2019, "month": 3, "day": 24, "type": "payment", "amount": 294 },
{ "year": 2019, "month": 3, "day": 24, "type": "payment", "amount": 260 },
{ "year": 2019, "month": 3, "day": 25, "type": "withdrawal", "amount": 200 },
{ "year": 2019, "month": 4, "day": 1, "type": "replenishment", "amount": 88656 },
{ "year": 2019, "month": 4, "day": 4, "type": "payment", "amount": 37852 },
{ "year": 2019, "month": 4, "day": 7, "type": "payment", "amount": 9365 },
{ "year": 2019, "month": 4, "day": 8, "type": "payment", "amount": 16701 },
{ "year": 2019, "month": 4, "day": 11, "type": "payment", "amount": 8979 },
{ "year": 2019, "month": 4, "day": 11, "type": "payment", "amount": 1971 },
{ "year": 2019, "month": 4, "day": 13, "type": "payment", "amount": 1261 },
{ "year": 2019, "month": 4, "day": 13, "type": "withdrawal", "amount": 800 },
{ "year": 2019, "month": 4, "day": 15, "type": "payment", "amount": 5553 },
{ "year": 2019, "month": 4, "day": 17, "type": "payment", "amount": 2593 },
{ "year": 2019, "month": 4, "day": 18, "type": "replenishment", "amount": 6915 },
{ "year": 2019, "month": 4, "day": 19, "type": "replenishment", "amount": 17647 },
{ "year": 2019, "month": 4, "day": 21, "type": "payment", "amount": 13814 },
{ "year": 2019, "month": 4, "day": 22, "type": "payment", "amount": 2707 },
{ "year": 2019, "month": 4, "day": 22, "type": "withdrawal", "amount": 1300 },
{ "year": 2019, "month": 4, "day": 22, "type": "withdrawal", "amount": 2900 },
{ "year": 2019, "month": 4, "day": 23, "type": "replenishment", "amount": 10709 },
{ "year": 2019, "month": 4, "day": 23, "type": "payment", "amount": 686 },
{ "year": 2019, "month": 4, "day": 23, "type": "withdrawal", "amount": 5100 },
{ "year": 2019, "month": 4, "day": 23, "type": "payment", "amount": 3830 },
{ "year": 2019, "month": 5, "day": 1, "type": "replenishment", "amount": 59877 },
{ "year": 2019, "month": 5, "day": 2, "type": "payment", "amount": 14095 },
{ "year": 2019, "month": 5, "day": 5, "type": "payment", "amount": 10858 },
{ "year": 2019, "month": 5, "day": 8, "type": "payment", "amount": 9412 },
{ "year": 2019, "month": 5, "day": 11, "type": "replenishment", "amount": 6892 },
{ "year": 2019, "month": 5, "day": 11, "type": "payment", "amount": 17541 },
{ "year": 2019, "month": 5, "day": 11, "type": "payment", "amount": 2666 },
{ "year": 2019, "month": 5, "day": 11, "type": "payment", "amount": 3935 },
{ "year": 2019, "month": 5, "day": 12, "type": "withdrawal", "amount": 2600 },
{ "year": 2019, "month": 5, "day": 14, "type": "payment", "amount": 2096 },
{ "year": 2019, "month": 5, "day": 14, "type": "replenishment", "amount": 2733 },
{ "year": 2019, "month": 5, "day": 15, "type": "replenishment", "amount": 538 },
{ "year": 2019, "month": 5, "day": 15, "type": "payment", "amount": 5324 },
{ "year": 2019, "month": 5, "day": 15, "type": "payment", "amount": 2490 },
{ "year": 2019, "month": 5, "day": 15, "type": "payment", "amount": 3510 },
{ "year": 2019, "month": 5, "day": 17, "type": "withdrawal", "amount": 300 },
{ "year": 2019, "month": 5, "day": 17, "type": "payment", "amount": 133 },
{ "year": 2019, "month": 6, "day": 1, "type": "replenishment", "amount": 89064 },
{ "year": 2019, "month": 6, "day": 2, "type": "payment", "amount": 7613 },
{ "year": 2019, "month": 6, "day": 2, "type": "payment", "amount": 33742 },
{ "year": 2019, "month": 6, "day": 5, "type": "withdrawal", "amount": 7200 },
{ "year": 2019, "month": 6, "day": 6, "type": "payment", "amount": 15125 },
{ "year": 2019, "month": 6, "day": 9, "type": "payment", "amount": 3379 },
{ "year": 2019, "month": 6, "day": 10, "type": "payment", "amount": 1260 },
{ "year": 2019, "month": 6, "day": 12, "type": "payment", "amount": 11066 },
{ "year": 2019, "month": 6, "day": 12, "type": "replenishment", "amount": 7050 },
{ "year": 2019, "month": 6, "day": 12, "type": "payment", "amount": 7531 },
{ "year": 2019, "month": 6, "day": 13, "type": "payment", "amount": 4776 },
{ "year": 2019, "month": 6, "day": 13, "type": "replenishment", "amount": 4456 },
{ "year": 2019, "month": 6, "day": 14, "type": "replenishment", "amount": 7998 },
{ "year": 2019, "month": 6, "day": 16, "type": "payment", "amount": 2437 },
{ "year": 2019, "month": 6, "day": 16, "type": "replenishment", "amount": 11729 },
{ "year": 2019, "month": 6, "day": 18, "type": "payment", "amount": 11216 },
{ "year": 2019, "month": 6, "day": 19, "type": "payment", "amount": 3420 },
{ "year": 2019, "month": 6, "day": 19, "type": "payment", "amount": 1339 },
{ "year": 2019, "month": 6, "day": 20, "type": "payment", "amount": 5578 },
{ "year": 2019, "month": 6, "day": 21, "type": "withdrawal", "amount": 1600 },
{ "year": 2019, "month": 6, "day": 21, "type": "withdrawal", "amount": 400 },
{ "year": 2019, "month": 7, "day": 1, "type": "replenishment", "amount": 51749 },
{ "year": 2019, "month": 7, "day": 2, "type": "payment", "amount": 2875 },
{ "year": 2019, "month": 7, "day": 2, "type": "payment", "amount": 10315 },
{ "year": 2019, "month": 7, "day": 5, "type": "payment", "amount": 18501 },
{ "year": 2019, "month": 7, "day": 5, "type": "payment", "amount": 12728 },
{ "year": 2019, "month": 7, "day": 7, "type": "payment", "amount": 4505 },
{ "year": 2019, "month": 7, "day": 8, "type": "payment", "amount": 2758 },
{ "year": 2019, "month": 7, "day": 8, "type": "payment", "amount": 60 },
{ "year": 2019, "month": 7, "day": 10, "type": "withdrawal", "amount": 1100 },
{ "year": 2019, "month": 7, "day": 12, "type": "withdrawal", "amount": 1000 },
{ "year": 2019, "month": 7, "day": 13, "type": "payment", "amount": 151 },
{ "year": 2019, "month": 8, "day": 1, "type": "replenishment", "amount": 85156 },
{ "year": 2019, "month": 8, "day": 1, "type": "payment", "amount": 33978 },
{ "year": 2019, "month": 8, "day": 2, "type": "payment", "amount": 6548 },
{ "year": 2019, "month": 8, "day": 3, "type": "payment", "amount": 5909 },
{ "year": 2019, "month": 8, "day": 6, "type": "payment", "amount": 2326 },
{ "year": 2019, "month": 8, "day": 6, "type": "payment", "amount": 17798 },
{ "year": 2019, "month": 8, "day": 9, "type": "replenishment", "amount": 10770 },
{ "year": 2019, "month": 8, "day": 10, "type": "withdrawal", "amount": 7400 },
{ "year": 2019, "month": 8, "day": 12, "type": "payment", "amount": 6065 },
{ "year": 2019, "month": 8, "day": 14, "type": "withdrawal", "amount": 900 },
{ "year": 2019, "month": 8, "day": 14, "type": "withdrawal", "amount": 1400 },
{ "year": 2019, "month": 8, "day": 14, "type": "payment", "amount": 4673 },
{ "year": 2019, "month": 8, "day": 15, "type": "payment", "amount": 960 },
{ "year": 2019, "month": 8, "day": 15, "type": "payment", "amount": 1085 },
{ "year": 2019, "month": 8, "day": 17, "type": "payment", "amount": 3723 },
{ "year": 2019, "month": 8, "day": 17, "type": "payment", "amount": 2522 },
{ "year": 2019, "month": 8, "day": 19, "type": "replenishment", "amount": 2496 },
{ "year": 2019, "month": 8, "day": 20, "type": "payment", "amount": 876 },
{ "year": 2019, "month": 8, "day": 20, "type": "payment", "amount": 2504 },
{ "year": 2019, "month": 8, "day": 21, "type": "payment", "amount": 826 },
{ "year": 2019, "month": 8, "day": 22, "type": "payment", "amount": 768 },
{ "year": 2019, "month": 8, "day": 23, "type": "withdrawal", "amount": 700 },
{ "year": 2019, "month": 8, "day": 23, "type": "payment", "amount": 190 },
{ "year": 2019, "month": 8, "day": 24, "type": "payment", "amount": 235 },
{ "year": 2019, "month": 9, "day": 1, "type": "replenishment", "amount": 95512 },
{ "year": 2019, "month": 9, "day": 3, "type": "payment", "amount": 26758 },
{ "year": 2019, "month": 9, "day": 3, "type": "replenishment", "amount": 8377 },
{ "year": 2019, "month": 9, "day": 4, "type": "payment", "amount": 30865 },
{ "year": 2019, "month": 9, "day": 4, "type": "withdrawal", "amount": 12800 },
{ "year": 2019, "month": 9, "day": 7, "type": "payment", "amount": 10518 },
{ "year": 2019, "month": 9, "day": 8, "type": "payment", "amount": 11007 },
{ "year": 2019, "month": 9, "day": 10, "type": "payment", "amount": 5613 },
{ "year": 2019, "month": 9, "day": 10, "type": "withdrawal", "amount": 1700 },
{ "year": 2019, "month": 9, "day": 12, "type": "payment", "amount": 2237 },
{ "year": 2019, "month": 9, "day": 14, "type": "payment", "amount": 885 },
{ "year": 2019, "month": 9, "day": 14, "type": "payment", "amount": 977 },
{ "year": 2019, "month": 9, "day": 15, "type": "payment", "amount": 766 },
{ "year": 2019, "month": 9, "day": 17, "type": "payment", "amount": 360 },
{ "year": 2019, "month": 9, "day": 18, "type": "payment", "amount": 116 },
{ "year": 2019, "month": 9, "day": 18, "type": "withdrawal", "amount": 200 },
{ "year": 2019, "month": 9, "day": 19, "type": "payment", "amount": 115 },
{ "year": 2019, "month": 9, "day": 20, "type": "payment", "amount": 50 },
{ "year": 2019, "month": 9, "day": 21, "type": "payment", "amount": 32 },
{ "year": 2019, "month": 10, "day": 1, "type": "replenishment", "amount": 90475 },
{ "year": 2019, "month": 10, "day": 1, "type": "replenishment", "amount": 8845 },
{ "year": 2019, "month": 10, "day": 2, "type": "payment", "amount": 7121 },
{ "year": 2019, "month": 10, "day": 3, "type": "payment", "amount": 27955 },
{ "year": 2019, "month": 10, "day": 3, "type": "payment", "amount": 23079 },
{ "year": 2019, "month": 10, "day": 4, "type": "payment", "amount": 5948 },
{ "year": 2019, "month": 10, "day": 7, "type": "withdrawal", "amount": 4400 },
{ "year": 2019, "month": 10, "day": 8, "type": "payment", "amount": 9677 },
{ "year": 2019, "month": 10, "day": 9, "type": "payment", "amount": 3912 },
{ "year": 2019, "month": 10, "day": 9, "type": "replenishment", "amount": 3870 },
{ "year": 2019, "month": 10, "day": 9, "type": "payment", "amount": 6949 },
{ "year": 2019, "month": 10, "day": 10, "type": "withdrawal", "amount": 3400 },
{ "year": 2019, "month": 10, "day": 10, "type": "replenishment", "amount": 7471 },
{ "year": 2019, "month": 10, "day": 10, "type": "payment", "amount": 5962 },
{ "year": 2019, "month": 10, "day": 10, "type": "payment", "amount": 4990 },
{ "year": 2019, "month": 10, "day": 10, "type": "withdrawal", "amount": 3000 },
{ "year": 2019, "month": 10, "day": 11, "type": "withdrawal", "amount": 200 },
{ "year": 2019, "month": 10, "day": 12, "type": "withdrawal", "amount": 1300 },
{ "year": 2019, "month": 10, "day": 13, "type": "payment", "amount": 986 },
{ "year": 2019, "month": 10, "day": 14, "type": "replenishment", "amount": 4225 },
{ "year": 2019, "month": 10, "day": 15, "type": "withdrawal", "amount": 900 },
{ "year": 2019, "month": 10, "day": 17, "type": "payment", "amount": 864 },
{ "year": 2019, "month": 10, "day": 17, "type": "withdrawal", "amount": 1000 },
{ "year": 2019, "month": 10, "day": 18, "type": "payment", "amount": 801 },
{ "year": 2019, "month": 10, "day": 19, "type": "withdrawal", "amount": 300 },
{ "year": 2019, "month": 10, "day": 20, "type": "payment", "amount": 530 },
{ "year": 2019, "month": 11, "day": 1, "type": "replenishment", "amount": 80285 },
{ "year": 2019, "month": 11, "day": 3, "type": "payment", "amount": 38155 },
{ "year": 2019, "month": 11, "day": 6, "type": "payment", "amount": 10260 },
{ "year": 2019, "month": 11, "day": 9, "type": "payment", "amount": 11013 },
{ "year": 2019, "month": 11, "day": 10, "type": "payment", "amount": 1232 },
{ "year": 2019, "month": 11, "day": 12, "type": "withdrawal", "amount": 5100 },
{ "year": 2019, "month": 11, "day": 12, "type": "payment", "amount": 1192 },
{ "year": 2019, "month": 11, "day": 13, "type": "withdrawal", "amount": 4500 },
{ "year": 2019, "month": 11, "day": 14, "type": "replenishment", "amount": 4304 },
{ "year": 2019, "month": 11, "day": 15, "type": "withdrawal", "amount": 700 },
{ "year": 2019, "month": 11, "day": 15, "type": "replenishment", "amount": 15857 },
{ "year": 2019, "month": 11, "day": 17, "type": "payment", "amount": 9134 },
{ "year": 2019, "month": 11, "day": 19, "type": "payment", "amount": 8090 },
{ "year": 2019, "month": 11, "day": 20, "type": "payment", "amount": 2117 },
{ "year": 2019, "month": 11, "day": 20, "type": "withdrawal", "amount": 2700 },
{ "year": 2019, "month": 11, "day": 21, "type": "withdrawal", "amount": 2200 },
{ "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 258 },
{ "year": 2019, "month": 11, "day": 21, "type": "withdrawal", "amount": 1200 },
{ "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 1966 },
{ "year": 2019, "month": 11, "day": 21, "type": "withdrawal", "amount": 200 },
{ "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 493 },
{ "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 396 },
{ "year": 2019, "month": 11, "day": 21, "type": "withdrawal", "amount": 200 },
{ "year": 2019, "month": 11, "day": 21, "type": "payment", "amount": 134 },
{ "year": 2019, "month": 11, "day": 22, "type": "replenishment", "amount": 4815 },
{ "year": 2019, "month": 11, "day": 22, "type": "withdrawal", "amount": 500 },
{ "year": 2019, "month": 11, "day": 23, "type": "payment", "amount": 1793 },
{ "year": 2019, "month": 12, "day": 1, "type": "replenishment", "amount": 93524 },
{ "year": 2019, "month": 12, "day": 2, "type": "payment", "amount": 44289 },
{ "year": 2019, "month": 12, "day": 2, "type": "payment", "amount": 7724 },
{ "year": 2019, "month": 12, "day": 4, "type": "payment", "amount": 9420 },
{ "year": 2019, "month": 12, "day": 4, "type": "withdrawal", "amount": 3200 },
{ "year": 2019, "month": 12, "day": 4, "type": "payment", "amount": 651 },
{ "year": 2019, "month": 12, "day": 6, "type": "payment", "amount": 9259 },
{ "year": 2019, "month": 12, "day": 6, "type": "withdrawal", "amount": 5700 },
{ "year": 2019, "month": 12, "day": 7, "type": "payment", "amount": 1298 },
{ "year": 2019, "month": 12, "day": 9, "type": "payment", "amount": 3108 },
{ "year": 2019, "month": 12, "day": 11, "type": "withdrawal", "amount": 4300 },
{ "year": 2019, "month": 12, "day": 13, "type": "withdrawal", "amount": 200 },
{ "year": 2019, "month": 12, "day": 13, "type": "replenishment", "amount": 9096 },
{ "year": 2019, "month": 12, "day": 14, "type": "payment", "amount": 7205 },
{ "year": 2019, "month": 12, "day": 16, "type": "payment", "amount": 658 },
{ "year": 2019, "month": 12, "day": 17, "type": "replenishment", "amount": 9654 }
]首先，對于 task_1，我得到一個包含鍵“月”的值的物件：
var arr1 = ops.map(function(item){
return item.month
})
然后我找到結果陣列中唯一值的總和：
quantity var = {};
for (var i = 0; i <arr1.length; i ){
quantity [arr1[i]] = 1 (quantity [arr1[i]]|/ 0);
}
我得到以下形式的計數物件：
counts
{1: 27, 2: 11, 3: 23, 4: 20, 5: 17, 6: 21, 7: 11, 8: 24, 9: 19, 10: 26, 11: 27, 12: 16}
之后，我排序以找到 3 個最大值：
function findMax 3(obj){
var res = [-1,-1,-1];
for (let key in obj){
res[3] = obj[key];
res.sort(function(a,b){return b-a});
}
res.pop();
return res;
}
console.log(findMax3(counts));
在控制臺中，我得到以下資訊：
[27, 27, 26]
但與此同時，我不再知道與這些值相關的月份的索引
謝謝您的回答！
uj5u.com熱心網友回復：
為了解決這些問題，這里是提示“GroupBy using reduce”
至于任務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
}
一旦你理解了任務 1 是如何解決的，任務 2 就會變得簡單一點
任務 2 的解決方案
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)
};
});
}
如果您已經解決了任務 2，則任務 3 只是將 reduce/map 添加到任務 2 的解決方案中。
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;
})
}
uj5u.com熱心網友回復：
任務1
const task_1 = (arr, top = 3) => {
const ops = arr.reduce((acc, {year, month}) => {
const accByMonth = acc.find((obj) => (obj.month === month));
if (accByMonth) {
accByMonth.opsCount =1;
} else {
acc.push({ year, month, opsCount: 1 })
}
return acc;
}, []);
const sortedOps = ops.sort(
(obj1, obj2) => (obj2.opsCount - obj1.opsCount)
);
return sortedOps.slice(0, top);
}
console.log(task_1(data));
//[
// { year: 2019, month: 1, opsCount: 27 },
// { year: 2019, month: 11, opsCount: 27 },
// { year: 2019, month: 10, opsCount: 26 }
//]
任務 2
const getTotalByType = (arr, type) => arr
.filter((obj) => obj.type === type)
.reduce((sum, { amount }) => sum amount, 0);
const getRank = (ratio) =>{
const ranks = [[0.15, 'Gold'], [0.3, 'Silver'], [Infinity, 'Bronze']]
return ranks.find(([ rankRatio ]) => ratio < rankRatio)[1];
}
const task_2 = (year, month, arr) => {
const filteredData = arr.filter((obj) => (obj.year === year) && (obj.month === month));
const maxDay = Math.max(...filteredData.map(({ day }) => day));
const date = new Date(year, month - 1, maxDay).toISOString().split('T')[0];
const monthReplenishment = getTotalByType(filteredData, 'replenishment');
const monthPayment = getTotalByType(filteredData, 'payment');
const monthWithdrawal = getTotalByType(filteredData, 'withdrawal');
const monthBalance = monthReplenishment - monthPayment - monthWithdrawal;
const withdrawalRate = parseFloat((monthWithdrawal / monthReplenishment).toFixed(4));
const rank = getRank(withdrawalRate);
return {
date,
monthBalance,
monthWithdrawal,
withdrawalRate,
rank,
}
};
console.log(task_2(2019, 7, data));
//{
// date: '2019-07-13',
// monthBalance: -2244,
// monthWithdrawal: 2100,
// withdrawalRate: 0.0406,
// rank: 'Gold'
//}
任務 3
const getPeriods = (arr) => arr.
reduce((acc, {year, month}) => {
const isPeriodInAcc = acc.some(
(obj) => (obj.month === month) && (obj.year === year)
);
if (!isPeriodInAcc) {
acc.push({ year, month })
}
return acc;
}, [])
const task_3 = (arr, initialBalance = 0) => {
const periods = getPeriods(arr);
let totalBalance = initialBalance;
return periods.map(({ year, month }) => {
const opsByPeriod = task_2(year, month, arr);
totalBalance = opsByPeriod.monthBalance;
return {...opsByPeriod, totalBalance}
});
}
console.log(task_3(data));
//[
// {
// date: '2019-01-22',
// monthBalance: 3829,
// monthWithdrawal: 33800,
// withdrawalRate: 0.3134,
// rank: 'Bronze',
// totalBalance: 3829
// },
// ...
// {...},
//]
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標籤：javascript 数组 json 选择 降低