Manipulating Dates with Day.js — Set the Year of a Date and Get Max Values Between Multiple Dates

Day.js is a JavaScript library that lets us manipulate dates in our apps.

In this article, we’ll look at how to use Day.js to manipulate dates in our JavaScript apps.

Set the Quarter of the Year of a Date

To set the quarter of the year in a Day.js date we can use the quarter method available with the quarterOfYear plugin:

const dayjs = require("dayjs");
const quarterOfYear = require("dayjs/plugin/quarterOfYear");
dayjs.extend(quarterOfYear);

const result = dayjs().quarter(1);
console.log(result);

We import the quarterOfYear plugin with:

const quarterOfYear = require("dayjs/plugin/quarterOfYear");

And we set the quarter of the year to the first quarter by calling quarter with 1.

Set the Year of a Date

To set the year of a date in a Day.js date we can use the year method available with the year plugin:

const dayjs = require("dayjs");
const result = dayjs().year(2020);
console.log(result);

We set the year of the date to 2020 by calling year with 2020.

Maximum Between Multiple Dates

To get the maximum of multiple dates, we can use the max method available with the minMax plugin:

const dayjs = require("dayjs");
const minMax = require("dayjs/plugin/minMax");
dayjs.extend(minMax);

const result = dayjs.max(
  dayjs("2020-01-01"),
  dayjs("2018-01-01"),
  dayjs("2019-01-01")
);
console.log(result);

We import the minMax plugin with:

const minMax = require("dayjs/plugin/minMax");

And we get the max date from the dates we passed into the max method.

Conclusion

Day.js is a JavaScript library that lets us manipulate dates in our apps.