Get day works wrong in case new Date(year, month, day)-CodePudding

I'm trying to get day of week by :

const date = new Date('2021/12/06')
date.getDay()

and it works properly , but when I create date by using new Date(2021, 12, 6) , it show me wrong number - 4 . Why is it happens , or I don't understand some exception for this way of creating date object ?

CodePudding user response：

this is because month should be the month index (0 - 11) not the month order (1-12):

new Date(2021, 11, 6).getDay()

and not

new Date(2021, 12, 6).getDay()

REF: Date() constructor: syntax

CodePudding user response：

When you create a date by 3 params you have to use a month INDEX. Starting by 0.

So December is actually 11, not 12.

If you use new Date(2021, 11, 6) you get the result you're looking for.

CodePudding user response：

getDay() gets the index of the week. Sunday, Monday, Tuesday, etc. (0, 1, 2,3,...)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getDay

I believe what you're looking for is getDate() https://www.w3schools.com/js/js_date_methods.asp