I am trying to get the date before a given date in JavaScript. This is what I've come up with.
function getPreviousDay(year, month, day) {
const date = new Date(year, month - 1, day); // the month is 0-indexed
date.setDate(date.getDate() - 1);
console.log(`${date.getFullYear()}-${date.getMonth()}-${date.getDate()}`);
}
getPreviousDay(2016, 9, 30); // 2016-8-29, Expected output: 2016-9-29
getPreviousDay(2016, 10, 1); // 2016-8-30, Expected output: 2016-9-30
Why doesn't it work as expected? Thank you in advance!
You make month - 1, when initializing the date, but should be a month.
As you said, months, in js date object, are 0-indexed.
So you do very good to substract one from the month, when creating the date object.
Your problem is, that you don't add back that one month when showing the date object :
console.log(`${date.getFullYear()}-${date.getMonth() + 1}-${date.getDate()}`);