how to use the differenceincalendarisoweekyears function from the date-fns library in typescript

To use the differenceInCalendarISOWeekYears() function from the date-fns library in TypeScript, you first need to install the library and its types:

index.ts
npm install date-fns
npm install -D @types/date-fns
52 chars
3 lines

Once you have installed the library and its types, you can import the differenceInCalendarISOWeekYears() function and use it as follows:

index.ts
import { differenceInCalendarISOWeekYears } from 'date-fns';

const date1 = new Date(2015, 0, 1);
const date2 = new Date(2017, 11, 31);

const diff = differenceInCalendarISOWeekYears(date2, date1);

console.log(diff); // Output: 3
231 chars
9 lines

In this example, we imported the differenceInCalendarISOWeekYears() function from the date-fns library using import { differenceInCalendarISOWeekYears } from 'date-fns'.

We then created two Date objects representing January 1st, 2015 and December 31st, 2017, respectively.

We passed these two Date objects as arguments to the differenceInCalendarISOWeekYears() function to get the difference in ISO week years between the two dates.

Finally, we logged the result to the console, which should output 3, since there are three ISO week years between January 1st, 2015 and December 31st, 2017.