Section 1.1: Using Native JavaScript Date Methods

One method to find the week of the year for a specific date is by leveraging JavaScript's built-in date functions to manually calculate it. Here’s how you can do it:

const now = new Date(2021, 3, 1);

const onejan = new Date(now.getFullYear(), 0, 1);

const week = Math.ceil((((now.getTime() - onejan.getTime()) / 86400000) + onejan.getDay() + 1) / 7));

console.log(week);

In this example, we start with the date we want to analyze, referred to as now. We create another date, onejan, representing January 1 of the same year. The week number is calculated by first determining the difference in time between now and onejan, converting that into days, and then adjusting for the day of the week before dividing by 7 to get the number of weeks. Finally, we round the result up using Math.ceil, resulting in a week number of 14.

Section 1.2: Utilizing Moment.js

For a more straightforward approach, you can utilize the Moment.js library. This simplifies the process significantly:

const now = new Date(2021, 3, 1);

const week = moment(now).format('W');

console.log(week);

Here, we create a moment object by passing in our date and then use the .format('W') method to extract the week number. This method rounds down the result, giving us a week number of 13.