Get Monday and Sunday of the Week in JavaScript

To get the Monday and Sunday of the week, use the setDate() method to set the day of the month of a date to the Monday and Sunday of the week and pass the result to the Date() constructor.

const today = new Date()
const day = today.getDay()
const diff = today.getDate() - day + (day === 0 ? -6 : 1)
const monday = new Date(today.setDate(diff))

const sunday = new Date(monday)
sunday.setDate(sunday.getDate() + 6)

console.log(monday) // Monday November 21 2022
console.log(sunday) // Sunday November 27 2022

The getDate() method returns the day of the month (1 to 31) of a date.

The getDay() method returns the day of the week for the specified date according to local time: 0 for Sunday, 1 for Monday, 2 for Tuesday, and so on.

function getMonday(d) {
  date = new Date(d)
  const day = date.getDay()
  const diff = date.getDate() - day + (day === 0 ? -6 : 1)
  return new Date(d.setDate(diff))
}

function getThisWeek() {
  const monday = getMonday(new Date())
  const sunday = new Date(monday)
  sunday.setDate(sunday.getDate() + 6)
  return { monday, sunday }
}

const { monday, sunday } = getThisWeek()
console.log(monday) // Monday November 21 2022
console.log(sunday) // Sunday November 27 2022