month is shifted when parsing from a custom string.

[taimikam99]

Describe the bug
When parsed from the string to a dayjs instance, the month value is shifted.

Expected behavior

input

var dayjs = require("dayjs")
var customParseFormat = require('dayjs/plugin/customParseFormat')
dayjs.extend(customParseFormat)
console.log(dayjs("1996-02-02", "YYYY-MM-DD").month()); 
console.log(dayjs("1996-05-02", "YYYY-MM-DD").month());

output

2
5

Information

• Day.js Version v1.9.1
• OS: MacOS
• Browser chrome 86
• Time zone: [e.g. GMT-07:00 DST (Pacific Daylight Time)]

[iamkun]

Dayjs use 0 based month the same as the native Date object.

You can use dayjs().format('MM') to get the result you want.

[taimikam99]

@iamkun
Thank you! I'll try it.