用两个日期之间的日期填充对象数组

Question

我有一组对象，例如：

const dates = [
  {date: "Jul 06 2018", count: 10},
  {date: "Jul 08 2018", count: 1},
  {date: "Jul 10 2018", count: 120},
];

我正在使用 eachDay and format functions of date-fns 生成并 "backfill" 存在于给定数组的第一个日期和最后一个日期之间的所有日期。

eachDay(
  dates[0].date,
  dates.slice(-1)[0].date,
)
  .map(d => ({
    x: d.dateCollected,
    y: dates
      .filter(e => d.dateCollected === format(e, 'MMM DD YYYY')),
  }));

编码 returns 所有日期，但我无法将 count 值从原始数组获取到 "backfilled" 数组中。

预期结果：

const result =  = [
  {x: "Jul 06 2018", y: 10},
  {x: "Jul 07 2018", y: 0},
  {x: "Jul 08 2018", y: 1},
  {x: "Jul 09 2018", y: 0},
  {x: "Jul 10 2018", y: 120},
];

Answer 1

根据 eachDay 的文档，函数 returns 字符串值，而不是具有 dateCollected 属性的对象。

您可以像这样产生想要的结果：

const {eachDay, format} = dateFns; // Just needed for this snippet to run

const dates = [
  {date: "Jul 06 2018", count: 10},
  {date: "Jul 08 2018", count: 1},
  {date: "Jul 10 2018", count: 120},
];

const result = eachDay(
  dates[0].date,
  dates.slice(-1)[0].date,
).map(x => format(x, "MMM DD YYYY"))
.map(x => ({ x, y: (dates.find(d => d.date === x) || { count: 0 }).count }));

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/date-fns/1.30.1/date_fns.js"></script>

Answer 2

您可以通过按日期创建计数查找来简化事情：

const {eachDay, format} = dateFns;

const dates = [
  {date: "Jul 06 2018", count: 10},
  {date: "Jul 08 2018", count: 1},
  {date: "Jul 10 2018", count: 120}
];

const counts = dates.reduce((memo, {date, count}) => {
  memo[date] = count;
  return memo;
}, {});

const result = eachDay(
  dates[0].date,
  dates.slice(-1)[0].date
)
  .map(d => {
    const x = format(d, "MMM DD YYYY");
    return {x, y: counts[x] || 0};
  })

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/date-fns/1.30.1/date_fns.js"></script>

用两个日期之间的日期填充对象数组

Fill Array of Objects with Dates Between 2 Dates

javascript

date-fns