Issue with format() when using milliseconds

[joni7777]

Describe the bug
When you create a dayjs object, add 1 milliseconds to it and format to string, the string doesnt include the added milliseconds

const timestamp = dayjs();
console.log(timestamp.format('YYYY-MM-DDTHH:mm:ss.sss')) // ---> SAME
console.log(timestamp.add(1, 'millisecond').format('YYYY-MM-DDTHH:mm:ss.sss')) // ---> SAME
console.log(timestamp.add(0.001, 'second').format('YYYY-MM-DDTHH:mm:ss.sss')) // ---> SAME

Expected behavior
When you create a dayjs object, add 1 milliseconds to it and format to string, the string format should have the added milliseconds

const timestamp = dayjs();
console.log(timestamp.format('YYYY-MM-DDTHH:mm:ss.sss')) // ---> X
console.log(timestamp.add(1, 'millisecond').format('YYYY-MM-DDTHH:mm:ss.sss')) // ---> X + 1 milliseconds
console.log(timestamp.add(0.001, 'second').format('YYYY-MM-DDTHH:mm:ss.sss')) // ---> X + 1 milliseconds

Information

• Day.js Version v1.8.26

Example
https://runkit.com/joni7777/dayjs-milliseconds-issue

[iamkun]

https://runkit.com/embed/1wlzrozab430

seems ok?

[joni7777]

@iamkun Yea the valueOf() is working as expected, but the format() is not using the milliseconds

[joni7777]

It was may bad, i had a bad format for milliseconds, used 'YYYY-MM-DDTHH:mm:ss.sss' instead of 'YYYY-MM-DDTHH:mm:ss.SSS' (the .SSS in the end) 🤦‍♂️

[aaronamm]

As reference for others.
https://day.js.org/docs/en/display/format

Format	Output	Description
SSS	000-999	The millisecond, 3-digits