Overview of JavaScript Date Set Methods
The Date object offers various set methods to change date and time values:
| Method | Purpose | Example Input |
|---|---|---|
| setFullYear(year, month?, day?) | Sets the year (optionally, month and day) | 2025, 10, 15 |
| setMonth(month, day?) | Sets the month (0-11, where 0 = January) | 6 (July) |
| setDate(day) | Sets the day of the month (1-31) | 20 |
| setHours(hours, minutes?, seconds?, ms?) | Sets the hour (optionally, minutes, seconds, and milliseconds) | 15, 30, 0, 0 |
| setMinutes(minutes, seconds?, ms?) | Sets the minutes (optionally, seconds and milliseconds) | 45 |
| setSeconds(seconds, ms?) | Sets the seconds (optionally, milliseconds) | 50 |
| setMilliseconds(ms) | Sets the milliseconds (0-999) | 500 |
| setTime(milliseconds) | Sets the time in milliseconds since January 1, 1970 | 1692598450000 |
Detailed Explanation of Each Method
1. setFullYear()
This method sets the year for the Date object. You can optionally provide the month and day.
Syntax:
date.setFullYear(year, month, day);
Example:
const date = new Date();
date.setFullYear(2025);
console.log(date); // Output: Fri Nov 25 2025 ...
Setting year, month, and day together:
date.setFullYear(2025, 6, 20); // July 20, 2025
console.log(date); // Output: Sun Jul 20 2025 ...
2. setMonth()
This method updates the month of the Date object. Remember, months are zero-based (0 = January).
Syntax:
date.setMonth(month, day);
Example:
const date = new Date();
date.setMonth(0); // January
console.log(date); // Output: Thu Jan 25 2024 ...
Setting month and day together:
date.setMonth(11, 5); // December 5
console.log(date); // Output: Thu Dec 05 2024 ...
3. setDate()
This method sets the day of the month for the Date object.
Syntax:
date.setDate(day);
Example:
const date = new Date();
date.setDate(15);
console.log(date); // Output: Fri Nov 15 2024 ...
Handling overflow:
date.setDate(35); // Moves to the next month
console.log(date); // Output: Thu Dec 05 2024 ...
4. setHours()
This method sets the hour and optionally the minutes, seconds, and milliseconds.
Syntax:
date.setHours(hours, minutes, seconds, milliseconds);
Example:
const date = new Date();
date.setHours(10);
console.log(date); // Output: Fri Nov 25 2024 10:00:00 ...
Setting additional time components:
date.setHours(14, 45, 30); // 2:45:30 PM
console.log(date); // Output: Fri Nov 25 2024 14:45:30 ...
5. setMinutes()
This method sets the minutes and optionally the seconds and milliseconds.
Syntax:
date.setMinutes(minutes, seconds, milliseconds);
Example:
const date = new Date();
date.setMinutes(50);
console.log(date); // Output: Fri Nov 25 2024 10:50:00 ...
6. setSeconds()
This method updates the seconds and optionally the milliseconds.
Syntax:
date.setSeconds(seconds, milliseconds);
Example:
const date = new Date();
date.setSeconds(30);
console.log(date); // Output: Fri Nov 25 2024 10:50:30 ...
7. setMilliseconds()
This method modifies the milliseconds of the Date object.
Syntax:
date.setMilliseconds(milliseconds);
Example:
const date = new Date();
date.setMilliseconds(500);
console.log(date); // Output: Fri Nov 25 2024 10:50:30.500 ...
8. setTime()
This method sets the date and time based on the number of milliseconds since January 1, 1970.
Syntax:
date.setTime(milliseconds);
Example:
const date = new Date();
date.setTime(1692598450000);
console.log(date); // Output: Tue Aug 20 2024 12:00:50 ...
Practical Examples
Example 1: Modify a Specific Date
const date = new Date("2024-11-01T00:00:00");
date.setFullYear(2025);
date.setMonth(5); // June
date.setDate(15);
console.log(date); // Output: Sun Jun 15 2025 00:00:00 ...
Example 2: Set Future Meeting Time
const meetingDate = new Date();
meetingDate.setDate(meetingDate.getDate() + 7); // 7 days from today
meetingDate.setHours(10, 30, 0, 0); // 10:30 AM
console.log(meetingDate); // Output: Next week's date at 10:30 AM
Example 3: Adjust Time for a Countdown Timer
function setCountdown(durationInMinutes) {
const currentDate = new Date();
const countdownDate = new Date();
countdownDate.setMinutes(currentDate.getMinutes() + durationInMinutes);
return countdownDate;
}
console.log(setCountdown(30)); // Output: Current date + 30 minutes