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

The getISOWeeksInYear function from date-fns library returns the number of ISO weeks in the given year. You can use it in your JavaScript code in the following way:

index.tsx
const { getISOWeeksInYear } = require('date-fns');

const year = 2022;
const numOfISOWeeks = getISOWeeksInYear(new Date(year, 0, 1));

console.log(`Number of ISO weeks in ${year}: ${numOfISOWeeks}`);
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In this example, we first import the getISOWeeksInYear function from the date-fns library using destructuring. Then, we define the year variable and use the Date constructor to create a new date object with the first day of that year. Finally, we call the getISOWeeksInYear function with the created date object as a parameter and store the returned value in the numOfISOWeeks variable.

The output of this code would be:

index.tsx
Number of ISO weeks in 2022: 52
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Note that the getISOWeeksInYear function takes a Date object as a parameter and not a year number directly. Therefore, we use the Date constructor to create a new date object with the first day of the given year.