What's the difference between giving value to Date() by Number or String?

Question

When I giving value to Date() object by String and another by Numbers however parameters are similar, I got Different result in toLocaleString() method!

let date1 = new Date('1995 02 23');
date1.toLocaleString(); // "2/23/1995, 12:00:00 AM"

let date2 = new Date(1995, 02, 23)
date2.toLocaleString(); // "3/23/1995, 12:00:00 AM"

There is 1 month of difference between them.

When numbers given - months counts from `0` instead of `1` – Puwka Aug 15 '19 at 06:40 — Puwka, Aug 15 '19 at 06:40
*don't answer as comments ...* – Jonas Wilms Aug 15 '19 at 07:07 — Jonas Wilms, Aug 15 '19 at 07:07

score 0 · Accepted Answer · answered Aug 15 '19 at 07:15

With your help I found out in number mode, month like Arrays count from 0 and if giving Milliseconds argument to Date(), you must enter a value between 0 to 999 for it.

var myDate = new Date(1995, 1, 23, 14, 25, 30, 999);

myDate.getMilliseconds(); // 999
myDate.myDate.toLocaleString(); // "2/23/1995, 2:25:30 PM"

score 0 · Answer 2 · answered Aug 15 '19 at 07:18

Months are zero based in dates, therefore if you pass the number 2, it is treated as march. If you pass a string however it will try to parse it in a way a human would understand it, and dates are usually one based.

As a sidenote, new Date("somestring") was never really specified, and various browsers added support for various formats, therefore you cannot rely on it's behaviour. Date parse is specified and thus reliable.

What's the difference between giving value to Date() by Number or String?

2 Answers2