Get the Date of the Next Friday using JavaScript

Get the Date of the Next Friday using JavaScript #

To get the date of the next Friday:

1. Get the day of the month of the next Friday.
2. Pass the result to the setDate() method.
3. The setDate method changes the day of the month for the given date.

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function getNextFriday(date = new Date()) {
  const dateCopy = new Date(date.getTime());

  const nextFriday = new Date(
    dateCopy.setDate(
      dateCopy.getDate() + ((7 - dateCopy.getDay() + 5) % 7 || 7),
    ),
  );

  return nextFriday;
}

// 👇️ Get Friday of Next Week
console.log(getNextFriday(new Date())); // 👉️ Fri Jan 21 2022

// 👇️ Get Next Friday for specific Date
console.log(getNextFriday(new Date('2022-01-25'))); // 👉️ Fri Jan 28 2022

We created a reusable function that takes a Date object as a parameter and returns the next Friday.

If no parameter is provided, the function returns the next Friday of the current date.

The setDate method allows us to change the day of the month of a specific Date instance.

The method takes an integer that represents the day of the month.

To get the next Friday, we:

1. Add 5 to the day of the week, e.g. Tuesday = 7 - 2 (Tuesday) + 5 = 10. Note that the getDay() method returns the day of the week where Sunday is 0, Monday is 1, Tuesday is 2, etc.

2. Use the modulo operator to get the remainder of dividing 10 % 7 = 3

3. If the remainder is equal to 0, then the current date is Friday and we have to default it to 7 to get the date of the next Friday.

4. The getDate() method returns the day of the month, e.g. 18 + 3 = 21, where 21 is the day of the month for the next Friday.

If the Date object stores a Friday:

1. Get the day of the month, e.g. 21.
2. Calculate 7 - day of the week (Friday = 5) + 5 = 7
3. Get the remainder - 7 % 7 = 0 || 7 = 7.
4. Get the day of the month for the next Friday - 21 + 7 = 28, where 28 is the day of the month for the next Friday.

We created the dateCopy variable in the function because the setDate method mutates the Date instance in place.

If you use the same Date object elsewhere in your code, this might lead to confusing bugs.