How to Subtract Minutes From a Date in JavaScript
Let's learn how to easily subtract any number of minutes from a Date object in JavaScript.
1. Date getMinutes() and setMinutes() methods
To subtract minutes from a Date:
- Call the
getMinutes()method on theDateto get the minutes. - Subtract the minutes.
- Pass the difference to the
setMinutes()method.
For example:
function subtractMinutes(date, minutes) {
date.setMinutes(date.getMinutes() - minutes);
return date;
}
// 2:20 pm on May 18, 2022
const date = new Date('2022-05-18T14:20:00.000Z');
const newDate = subtractMinutes(date, 10);
// 2:10 pm on May 18, 2022
console.log(newDate); // 2022-05-18T14:10:00.000Z
Our subtractMinutes() function takes a Date object and the number of minutes to subtract as arguments. It returns the same Date object with the minutes subtracted.
The Date getMinutes() method returns a number between 0 and 59 that represent the minutes of a particular Date.
The Date setMinutes() method set the minutes of a Date to a specified number.
If the minutes subtracted decrease the hour, day, month, or year of the Date object, setMinutes() will automatically update the information in the Date to reflect this.
// 10:10 am on March 13, 2022
const date = new Date('2022-03-13T10:10:00.000Z');
date.setMinutes(date.getMinutes() - 30);
// 9:40 am on March 13, 2022
console.log(date); // 2022-05-18T14:10:00.000Z
In this example, decreasing the minutes of the Date by 30 rolls the hour back by 1.
Avoiding side effects
The setMinutes() method mutates the Date object it is called on. This introduces a side effect into our subtractMinutes() function. To avoid modifying the passed Date and create a pure function, make a copy of the Date and call setMinutes() on this copy, instead of the original.
function subtractMinutes(date, minutes) {
// 👇 make copy with "Date" constructor
const dateCopy = new Date(date);
dateCopy.setMinutes(date.getMinutes() - minutes);
return dateCopy;
}
const date = new Date('2022-02-20T11:25:00.000Z');
const newDate = subtractMinutes(date, 5);
// 11:20 am on Feb 20, 2022
console.log(newDate); // 2022-02-20T11:20:00.000Z
// 👇 Original not modified
console.log(date); // 2022-02-20T11:25:00.000Z
Tip: Functions that don’t modify external state (i.e., pure functions) tend to be more predictable and easier to reason about, as they always give the same output for a particular input. This makes it a good practice to limit the number of side effects in your code.
2. date-fns subMinutes() function
Alternatively, we can use the subMinutes() function from the date-fns NPM package to quickly subtract minutes from a Date in JavaScript. It works like our pure subtractMinutes() function.
import { subMinutes } from 'date-fns';
const date = new Date('2022-10-03T20:50:00.000Z');
const newDate = subMinutes(date, 25);
// 8:25 pm on October 3, 2022
console.log(newDate); // 2019-02-20T11:20:00.000Z
// Original not modified
console.log(date); // 2022-02-20T11:25:00.000Z
