how to use the startofisoweekyear function from date-fns in javascript

To use the startOfISOWeekYear function from date-fns, you first need to install the npm package date-fns.

You can then import the function into your javascript file like so:

index.tsx
import { startOfISOWeekYear } from 'date-fns';
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The startOfISOWeekYear function takes a Date object as its argument and returns a new Date object with the start of the ISO week-year.

Here's an example usage:

index.tsx
const date = new Date('2022-01-31');
const startOfISOWeekYear = startOfISOWeekYear(date);

console.log(startOfISOWeekYear);
// Output: 2021-12-27T00:00:00.000Z
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In this example, we create a new Date object with the date '2022-01-31'. We then pass this object into the startOfISOWeekYear function, which returns a new Date object with the start of the ISO week-year (in this case, December 27, 2021). We log this new Date object to the console.