基于对象数组与日期标签生成补全缺失日期的新数组

需求：基于给定的日期标签数组dailyLabels生成新数组，新数组需包含dailyLabels的所有日期条目。若dailyCurr中存在对应日期的条目则直接使用，不存在则用指定默认值填充（mov_date为空字符串、value为0、cod为null、product为空字符串、year为"curr"）。

给定数据 #

const dailyLabels = [
  "01/11",
  "02/11",
  "03/11",
  "04/11"
]

const dailyCurr = [
  {
    mov_date: "2022-11-03T14:16:10.694Z",
    value: 2,
    cod: 5,
    product: "ODONTO",
    day: "03/11",
    year: "curr"
  },
  {
    mov_date: "2022-11-04T14:16:10.694Z",
    value: 2,
    cod: 5,
    product: "ODONTO",
    day: "04/11",
    year: "curr"
  }
]

解决方案 #

基础实现（适用于小数据量） #

先定义默认值对象，遍历dailyLabels并匹配dailyCurr中的条目：

const defaultItem = {
  mov_date: "",
  value: 0,
  cod: null,
  product: "",
  year: "curr"
};

const thirdArray = dailyLabels.map(day => {
  // 查找对应日期的条目
  const matchedItem = dailyCurr.find(item => item.day === day);
  // 找到则返回条目拷贝，否则返回带当前日期的默认值
  return matchedItem ? { ...matchedItem } : { ...defaultItem, day };
});

优化实现（适用于大数据量） #

将dailyCurr转换为Map以提升查找效率（时间复杂度从O(n)降至O(1)）：

const defaultItem = {
  mov_date: "",
  value: 0,
  cod: null,
  product: "",
  year: "curr"
};

// 构建以day为键的映射表
const currDayMap = new Map(dailyCurr.map(item => [item.day, item]));

const thirdArray = dailyLabels.map(day => {
  const matchedItem = currDayMap.get(day);
  return matchedItem ? { ...matchedItem } : { ...defaultItem, day };
});

最终结果 #

执行上述代码后，thirdArray将与期望结果完全一致：

const thirdArray = [
    {
      mov_date: "",
      value: 0,
      cod: null,
      product: "",
      day: "01/11",
      year: "curr"
    },
    {
      mov_date: "",
      value: 0,
      cod: null,
      product: "",
      day: "02/11",
      year: "curr"
    },
    {
      mov_date: "2022-11-03T14:16:10.694Z",
      value: 2,
      cod: 5,
      product: "ODONTO",
      day: "03/11",
      year: "curr"
    },
    {
      mov_date: "2022-11-04T14:16:10.694Z",
      value: 2,
      cod: 5,
      product: "ODONTO",
      day: "04/11",
      year: "curr"
    }
  ]

内容的提问来源于stack exchange，提问作者devlpo