Manipulating Dates with Day.js — Parsing

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.

Parsing JavaScript Native Date Objects

We can pass in native JavaScript date objects as an argument of the dayjs function.

To do this, we write:

const d = new Date(2020, 8, 18)
const dt = dayjs(d)
console.log(dt)

Parsing Plain JavaScript Objects into Dates

To parse plain JavaScript objects into dates, we can use the objectSupport plugin.

For instance, we can write:

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

dayjs.extend(objectSupport);
const dt = dayjs({
  year: 2020,
  month: 3,
  day: 5,
  hour: 15,
  minute: 10,
  second: 3,
  millisecond: 123
});
console.log(dt);

We import the dayjs and dayjs/plugin/objectSupport modules to add the day.js library with the objectSupport plugin.

Then we add:

dayjs.extend(objectSupport);

to add the objectSupport plugin.

Now we can pass in an object into the dayjs function to parse it into a date.

Parsing JavaScript Array into Dates

Day.js also comes with the ArraySupport plugin that lets us parse an array of numbers into dates.

For instance, we can write:

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

dayjs.extend(arraySupport);
const dt = dayjs([2020, 1, 14, 15, 25, 50, 125]);
console.log(dt);

to import the Day.js and arraySupport library respectively in the first 2 lines.

Then we add:

dayjs.extend(arraySupport);

to add the arraySupport plugin.

Now we can pass in an array into the dayjs function to parse the array into a date.

The order of the numbers in the array is year, month, day of the month, hour, minutes, seconds, and milliseconds.

Conclusion

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