Dayjs group by time-range

gistfile1.txt

var dayjs = require('dayjs')
var minMax = require('dayjs/plugin/minMax')
dayjs.extend(minMax)


const input = [
  {time: '2020-07-23T11:30:00Z', value: 1},
  {time: '2020-07-24T11:30:00Z', value: 1},
  {time: '2020-07-05T11:30:00Z', value: 2},
  {time: '2020-07-30T11:30:00Z', value: 3},
]

const param = 'week'
const times = input.map(x => dayjs(x.time))
const min = dayjs.min(times)
const max = dayjs.max(times)
const start = min.startOf(param)
const size = max.startOf(param).diff(start, param)
const ranges = new Array(size + 1)
  .fill(0)
  .map((_, i) => start.add(i, param))
const toString = (x) => dayjs(x).startOf(param).format('YYYY MM DD')
const dict = ranges.reduce((acc, x) => {
  const stringFormat = toString(x)
  acc[stringFormat] = []
  return acc
}, {})
const grouped = input.reduce((acc, x) => {
  const stringFormat = toString(x.time)
  dict[stringFormat].push(x)
  return acc
}, dict)
const average = array => array.reduce((acc, x) => acc + x.value, 0) / (array.length || 1)
const result = Object.fromEntries(Object.entries(grouped).map(([key, value]) => [key, average(value)]))

console.log(result)