JAVASCRIPT

set a previous year to the current date in javascript

const d = new Date();
d.setFullYear(d.getFullYear()-1);

console.log(d.toDateString()); // "Fri Oct 04 2019"

get previous year in javascript

const currentYear = new Date().getFullYear(); // 2020

const previousYear =  currentYear-1;

console.log(previousYear); // 2019