JavaScript Date Set Methods

The JavaScript Date object provides various methods to set (modify) specific parts of a date and time. These methods allow you to adjust components such as the year, month, day, hour, minute, and more. In this article, we'll explore the different set methods available in JavaScript for the Date object.

1. `setFullYear(year, month, day)`

The setFullYear() method sets the year for a specified date. Optionally, you can also specify the month and day.

Example:

const date = new Date('2024-07-19');
date.setFullYear(2025);
console.log(date);  // Output: Fri Jul 19 2025 ...

In this example, the year is updated to 2025.

2. `setMonth(month, day)`

The setMonth() method sets the month (0-11) for a specified date. Optionally, you can also specify the day.

Example:

const date = new Date('2024-07-19');
date.setMonth(11); // December
console.log(date);  // Output: Tue Dec 19 2024 ...

Here, the month is updated to December.

3. `setDate(day)`

The setDate() method sets the day of the month (1-31) for a specified date.

Example:

const date = new Date('2024-07-19');
date.setDate(25);
console.log(date);  // Output: Thu Jul 25 2024 ...

The day of the month is changed to the 25th.

4. `setHours(hours, minutes, seconds, milliseconds)`

The setHours() method sets the hour (0-23) for a specified date. You can also optionally specify minutes, seconds, and milliseconds.

Example:

const date = new Date('2024-07-19T13:45:00');
date.setHours(16, 30, 0);
console.log(date);  // Output: Fri Jul 19 2024 16:30:00 ...

The time is updated to 4:30 PM.

5. `setMinutes(minutes, seconds, milliseconds)`

The setMinutes() method sets the minutes (0-59) for a specified date. Optionally, you can also specify seconds and milliseconds.

Example:

const date = new Date('2024-07-19T13:45:00');
date.setMinutes(50, 30);
console.log(date);  // Output: Fri Jul 19 2024 13:50:30 ...

The minutes and seconds are updated to 50 and 30, respectively.

6. `setSeconds(seconds, milliseconds)`

The setSeconds() method sets the seconds (0-59) for a specified date. Optionally, you can also specify milliseconds.

Example:

const date = new Date('2024-07-19T13:45:00');
date.setSeconds(55);
console.log(date);  // Output: Fri Jul 19 2024 13:45:55 ...

The seconds are updated to 55.

7. `setMilliseconds(milliseconds)`

The setMilliseconds() method sets the milliseconds (0-999) for a specified date.

Example:

const date = new Date('2024-07-19T13:45:00.000');
date.setMilliseconds(250);
console.log(date);  // Output: Fri Jul 19 2024 13:45:00.250 ...

The milliseconds are updated to 250.

8. `setTime(milliseconds)`

The setTime() method sets the date and time based on the number of milliseconds since January 1, 1970 (the Unix Epoch).

Example:

const date = new Date();
date.setTime(1726684800000); // Equivalent to Fri Jul 19 2024 ...
console.log(date);  // Output: Fri Jul 19 2024 ...

This method allows setting the date and time with a timestamp.

9. `setTimezoneOffset(minutes)`

The setTimezoneOffset() method adjusts the time based on the difference (in minutes) between UTC and the local time zone. However, this method is not available in JavaScript; the timezone offset is typically managed by the system or browser settings.

Example:

// This method does not exist in JavaScript Date API

Adjustments for timezone are handled differently, often using libraries or external APIs.

Conclusion

The Date object’s set methods are useful for modifying specific parts of a date and time in JavaScript. Understanding these methods allows you to perform precise date and time manipulations, making it easier to handle various time-based operations in your applications.

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