Javascript date helpers

Jan 7 2023

dayOfYear

This snippet gets the day of the year from a Date object.

const dayOfYear = (date) =>
  Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24)

dayOfYear(new Date()) // 272

Get Time From Date

This snippet can be used to get the time from a Date object as a string.

const getColonTimeFromDate = (date) => date.toTimeString().slice(0, 8)

getColonTimeFromDate(new Date()) // "08:38:00"

Calculate the interval between two dates

const dayDiff = (d1, d2) =>
  Math.ceil(Math.abs(d1.getTime() - d2.getTime()) / (1000 * 60 * 60 * 24))

dayDiff(new Date('2023-06-23'), new Date('1997-05-31')) // 9519

isAfterDate

This snippet can be used to check whether a date is after another date.

const isAfterDate = (dateA, dateB) => dateA > dateB

isAfterDate(new Date(2010, 10, 21), new Date(2010, 10, 20)) // true

isBeforeDate

This snippet can be used to check whether a date is before another date.

const isBeforeDate = (dateA, dateB) => dateA < dateB

isBeforeDate(new Date(2010, 10, 20), new Date(2010, 10, 21)) // true

isSameDate

This snippet can be used to check whether two dates are equal.

const isSameDate = (dateA, dateB) => dateA.toISOString() === dateB.toISOString()

isSameDate(new Date(2010, 10, 20), new Date(2010, 10, 20)) // true

maxDate

This snippet can be used to get the latest date.

const maxDate = (...dates) => new Date(Math.max.apply(null, ...dates))

const array = [
  new Date(2017, 4, 13),
  new Date(2018, 2, 12),
  new Date(2016, 0, 10),
  new Date(2016, 0, 9),
]
maxDate(array) // 2018-03-11T22:00:00.000Z

minDate

This snippet can be used to get the earliest date.

const minDate = (...dates) => new Date(Math.min.apply(null, ...dates))

const array = [
  new Date(2017, 4, 13),
  new Date(2018, 2, 12),
  new Date(2016, 0, 10),
  new Date(2016, 0, 9),
]
minDate(array) // 2016-01-08T22:00:00.000Z

tomorrow

This snippet can be used to get a string representation of tomorrow’s date.

const tomorrow = () => {
  let t = new Date()
  t.setDate(t.getDate() + 1)
  return t.toISOString().split('T')[0]
}

tomorrow() // 2019-09-09 (if current date is 2019-09-08)