How to get the total number of days in a year in JavaScript

In this Article we will go through how to get the total number of days in a year 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 numberOfDays = year => (((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0)) ? 366 : 365;

const numberOfDays = year => new Date(year, 1, 29).getDate() === 29 ? 366 : 365;