functions for computing time windows for data series

timeseries.js

const interval = {
  millisecond: 1,
  second: 1000,
  minute: 1000 * 60,
  hour: 1000 * 60 * 60,
  day: 1000 * 60 * 60 * 24
}

const period = 'day'
const d1 = truncate(new Date('2020-01-01 22:22:22'), period)
const d2 = truncate(new Date(), period)

console.error(d1)
console.error(d2)

for (let i = d1.getTime(); i <= d2.getTime(); i += interval[period]){
  console.error(i)
}

function truncate(d, period){
  const r = new Date(0)

  r.setFullYear(d.getFullYear())
  if(period === 'year'){ return r }

  r.setMonth(d.getMonth())
  if (period === 'month') { return r }

  r.setDate(d.getDate())
  if (period === 'day') { return r }

  r.setHours(d.getHours())
  if (period === 'hour') { return r }

  r.setMinutes(d.getMinutes())
  if (period === 'minute') { return r }

  r.setSeconds(d.getSeconds())
  if (period === 'second') { return r }

  r.setMilliseconds(d.getMilliseconds())
  return r
}