How to get the day of the year from a date in JavaScript

In this Article we will go through how to get the day of the year from a date only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const dayOfYear = date => Math.floor((date - new Date(date.getFullYear(), 0, 0)) / (1000 * 60 * 60 * 24));

Parameters date is a Date object.

dayOfYear(new Date(2020, 04, 16));      // 137