Finding the date of a month prior based on a fixed initial date - here's how!

Question

Finding the date of a month prior based on a fixed initial date - here's how!

I have a specific requirement to display a subscription date range on a webpage in the following format:

31 May 2023 — 30 June 2023

When a user subscribes, the backend sends a fixed subscription start date that remains constant. For example, if a user subscribes on 31 May 2023, the start date will be:

const startDate = "2023-05-31T10:16:14+00:00"

In addition, there are nextDates when new credits will be added to the user's account.

  const nextDate = "2023-06-30T10:16:20.404358+00:00",
  const nextDate1 = "2023-07-31T10:16:20.404358+00:00",
  const nextDate2 = "2023-08-31T10:16:20.404358+00:00",

My query is how can I determine the start date for each nextDate? The desired output should be as follows:

const startDate = "2023-05-31T10:16:14+00:00"
const nextDate = "2023-06-30T10:16:20.404358+00:00" // The start date should be 31 May 2023
const nextDate1 = "2023-07-31T10:16:20.404358+00:00" // The start date should be 30 June 2023

I attempted a solution but ended up with incorrect results:

const getPreviousInterval = (nextDate, months) => {
  const date = new Date(nextDate);
  const dateMonthsAgoUnix = date.setMonth(date.getMonth() - months);

  return new Date(dateMonthsAgoUnix);
};

getPreviousInterval("2023-06-30T10:16:20.404358+00:00", 1);
// Incorrect output is 2023-05-30T10:16:20.404Z
// Correct output should be 2023-05-31T10:16:14+00:00

javascript

Answer 1

Answer №1

It appears that you are interested in retrieving the final day of the previous month rather than simply going back "one month". For more information on how setDate(0) functions in this context, please refer to this link.

function getLastDayOfPreviousMonth(targetDate, monthsToGoBack) {
  const referenceDate = new Date(targetDate);
  referenceDate.setMonth(referenceDate.getMonth() - monthsToGoBack + 1);
  referenceDate.setDate(0); // Setting date to 0 gives us the last day of the preceding month
  return referenceDate;
};

console.log(getLastDayOfPreviousMonth("2023-06-30T10:16:20.404358+00:00", 1));

console.log(getLastDayOfPreviousMonth("2023-06-30T10:16:20.404358+00:00", 4));

console.log(getLastDayOfPreviousMonth("2023-06-30T10:16:20.404358+00:00", 40));

Answer 2

It appears that you are interested in retrieving the final day of the previous month rather than simply going back "one month". For more information on how setDate(0) functions in this context, please refer to this link.

function getLastDayOfPreviousMonth(targetDate, monthsToGoBack) {
  const referenceDate = new Date(targetDate);
  referenceDate.setMonth(referenceDate.getMonth() - monthsToGoBack + 1);
  referenceDate.setDate(0); // Setting date to 0 gives us the last day of the preceding month
  return referenceDate;
};

console.log(getLastDayOfPreviousMonth("2023-06-30T10:16:20.404358+00:00", 1));

console.log(getLastDayOfPreviousMonth("2023-06-30T10:16:20.404358+00:00", 4));

console.log(getLastDayOfPreviousMonth("2023-06-30T10:16:20.404358+00:00", 40));

Answer 3

Answer №2

If you want to create a sequence of upcoming dates, consider incrementing the month and then adding one day in milliseconds each time.

To display these dates in British format, utilize the Intl.DateTimeFormat class.

const dateFormatter = new Intl.DateTimeFormat('en-GB',  // UK date format
  { day: '2-digit', month: 'short', year: 'numeric' }); // DD MMM YYYY

const formatDateRange = (fromDate, toDate) => `${dateFormatter.format(fromDate)} — ${dateFormatter.format(toDate)}`;

const computeFutureMonths = (startDate, months) => {
  const results = [], currDate = new Date(startDate.getTime());
  for (let i = 0; i < months; i++) {
    currDate.setMonth(currDate.getMonth() + 1);
    results.push(new Date(currDate.getTime() - 8.64e7)); // Subtract 1 day in ms
  }
  return results;
};

const startDate = new Date('2023-05-31T10:16:14+00:00');
const nextThreeMonths = computeFutureMonths(startDate, 3);

nextThreeMonths.forEach(date => {
  console.log(date.toISOString());
});

// 31 May 2023 — 30 Jun 2023
console.log(formatDateRange(startDate, nextThreeMonths[0]));

Answer 4

If you want to create a sequence of upcoming dates, consider incrementing the month and then adding one day in milliseconds each time.

To display these dates in British format, utilize the Intl.DateTimeFormat class.

const dateFormatter = new Intl.DateTimeFormat('en-GB',  // UK date format
  { day: '2-digit', month: 'short', year: 'numeric' }); // DD MMM YYYY

const formatDateRange = (fromDate, toDate) => `${dateFormatter.format(fromDate)} — ${dateFormatter.format(toDate)}`;

const computeFutureMonths = (startDate, months) => {
  const results = [], currDate = new Date(startDate.getTime());
  for (let i = 0; i < months; i++) {
    currDate.setMonth(currDate.getMonth() + 1);
    results.push(new Date(currDate.getTime() - 8.64e7)); // Subtract 1 day in ms
  }
  return results;
};

const startDate = new Date('2023-05-31T10:16:14+00:00');
const nextThreeMonths = computeFutureMonths(startDate, 3);

nextThreeMonths.forEach(date => {
  console.log(date.toISOString());
});

// 31 May 2023 — 30 Jun 2023
console.log(formatDateRange(startDate, nextThreeMonths[0]));

Answer 5

Answer №3

let currentDate = new Date(Date.now());
const oneMonthEarlier = new Date(currentDate.setMonth(currentDate.getMonth() - 1));

console.log(oneMonthEarlier);

Answer 6

let currentDate = new Date(Date.now());
const oneMonthEarlier = new Date(currentDate.setMonth(currentDate.getMonth() - 1));

console.log(oneMonthEarlier);

Answer 7

Answer №4

Many solutions suggested here revolve around subtracting a month, but that approach may not work as expected.

const d = new Date("2023-05-31T10:16:14+00:00");
d.setMonth(d.getMonth() -1);
console.log(d);
//result "2023-05-01T10:16:14.000Z"

It's interesting to note how the date turns out to be the 1st in this case.

Alternatively, another method to find the end of the previous month is by setting the date to 0.

For example:

const d = new Date("2023-05-31T10:16:14+00:00");
d.setDate(0);
console.log(d);
//result "2023-04-30T10:16:14.000Z"

If you need to go back multiple months, you can use setMonth for all except the last one, where you should utilize setDate(0).

For instance, consider going back 3 months:

const d = new Date("2023-05-31T10:16:14+00:00");
d.setMonth(d.getMonth() -2);
d.setDate(0);
console.log(d);
//result "2023-02-28T11:16:14.000Z"

If nextDate is 2023-06-05T10:16:20.404358+00:00 then output should be 2023-05-05T10:16:20.404358+00:00...how can I handle this case?

In such cases, it's important to compare the current date with the obtained date since there are variations among months. If the current date exceeds the max days in the previous month, temporarily set the date to the highest valid value.

Here's an example:

const d = new Date("2023-06-05T10:16:20.404358+00:00");
const oldDate = d.getDate();
d.setDate(0);
if (oldDate < d.getDate()) d.setDate(oldDate);
console.log(d);
//result "2023-05-05T10:16:20.404Z"

Answer 8

Many solutions suggested here revolve around subtracting a month, but that approach may not work as expected.

const d = new Date("2023-05-31T10:16:14+00:00");
d.setMonth(d.getMonth() -1);
console.log(d);
//result "2023-05-01T10:16:14.000Z"

It's interesting to note how the date turns out to be the 1st in this case.

Alternatively, another method to find the end of the previous month is by setting the date to 0.

For example:

const d = new Date("2023-05-31T10:16:14+00:00");
d.setDate(0);
console.log(d);
//result "2023-04-30T10:16:14.000Z"

If you need to go back multiple months, you can use setMonth for all except the last one, where you should utilize setDate(0).

For instance, consider going back 3 months:

const d = new Date("2023-05-31T10:16:14+00:00");
d.setMonth(d.getMonth() -2);
d.setDate(0);
console.log(d);
//result "2023-02-28T11:16:14.000Z"

If nextDate is 2023-06-05T10:16:20.404358+00:00 then output should be 2023-05-05T10:16:20.404358+00:00...how can I handle this case?

In such cases, it's important to compare the current date with the obtained date since there are variations among months. If the current date exceeds the max days in the previous month, temporarily set the date to the highest valid value.

Here's an example:

const d = new Date("2023-06-05T10:16:20.404358+00:00");
const oldDate = d.getDate();
d.setDate(0);
if (oldDate < d.getDate()) d.setDate(oldDate);
console.log(d);
//result "2023-05-05T10:16:20.404Z"

Answer 9

Answer №5

// This code snippet retrieves today's date
const currentDate = new Date();

// This code calculates the date from one month ago
const oneMonthAgoDate = new Date();
oneMonthAgoDate.setMonth(oneMonthAgoDate.getMonth() - 1);

console.log("Today's date is " + currentDate.toLocaleDateString() + ".");
console.log("The date from one month ago was " + oneMonthAgoDate.toLocaleDateString() + ".");

Answer 10

// This code snippet retrieves today's date
const currentDate = new Date();

// This code calculates the date from one month ago
const oneMonthAgoDate = new Date();
oneMonthAgoDate.setMonth(oneMonthAgoDate.getMonth() - 1);

console.log("Today's date is " + currentDate.toLocaleDateString() + ".");
console.log("The date from one month ago was " + oneMonthAgoDate.toLocaleDateString() + ".");

Finding the date of a month prior based on a fixed initial date - here's how!

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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