Getting wrong month in moment.js

Question

I'm using Moment.js included through RequireJS. When I call Moment().month(), instead of number 11 I always get number 10. Any ideas how can this happen?

Raper

Isn't january month 0? Note: Months are zero indexed, so January is month 0. – Promontory

in javascript's Date, months are counted 0-11. w3schools.com/jsref/jsref_obj_date.asp – Eartha

Try Moment().format("MM") – Mesopause

You can always use the .add method to account for the zero index .add(1, 'M') – Barefaced

@JeremyHamm That doesn't work for December. moment.parseZone('12/01/2018','MM/DD/YYYY').add({M:1}).month() – Philpot

Thank you @RenatoGama : it returns the correct month number, starting from one. – Samba

Answer 1

According to Moment.js documentation, 'month' uses an array and the indices of an array are zero-based. Therefore, January is set to '0' and December is set to '11'.

For example, moment().month('November'); prints '10'.

Halie

Just a clarification. 0-based indexing of the months is a feature that Moment.js inherits from Javascript. See the ECMAScript specification at par.15.9.1.4 for further details. – Trilby

Almost feels like they should expose it as 1-12 for the sake of intuitive use in lieu of the the ECMAScript specification. – Cartogram

by this logic why arent year, date, hours and minutes zero based?(snark, sorry) – Bloodred

They actually claim month is not zero based: M MM 1..12 Month number – Furman

working link to ECMAScript month spec: ecma-international.org/ecma-262/5.1/#sec-15.9.1.4 – Computerize

We should create a dedicated web page that states the total dev time wasted by this. – Lindsay

Answer 2

moment().month gets or sets the month and accepts numbers from 0 to 11. Key here is that index starts at 0, not 1. The below code will work as a solution for this question.

{Moment(yourDate).month(Moment(yourDate).month()-1).format("MMMM Do YYYY")}

The above code for 8/30/2022 will show August 30th 2022.

{Moment(yourDate).month(Moment(yourDate).month()-1).format("MM-DD-YYYY")}

The above code for 8/30/2022 will show 08-30-2022.

{Moment(yourDate).format("MM-DD-YYYY")}

The above code for 8/30/2022 will show 09-30-2022.

Varve