Parsing '2020-12-20T15:00:00+08' is broken in 1.10+

Describe the bug

const day = require('dayjs');
console.log(`result:${dayjs('2020-12-20T15:00:00+08').format()}`);

In Day.js v1.9.8, we got result:2020-12-20T15:00:00+08:00. In Day.js v1.10.7, we got result:Invalid Date.

Is this a new feature or breaking change?

Expected behavior we expect the result is result:2020-12-20T15:00:00+08:00.

Information

• Day.js: 1.10.7
• OS: Ubuntu 20.04.1
• Node.js: v.16.9.1
• Time zone: Asia/Taipei (CST, +0800)

[Mirochiu]

It is difficult to check because the difference between versions is too large. Can you narrow the gap?

1.10.7 => 2021-09-10 1.9.8 => 2020-12-27

I’ve test v1.10.0. The result:Invalid Date.

[Mirochiu]

Using an offset in a date/time string requires the customParseFormat’ plugin to work.

I am on dayjs 1.11.2 and this test works for me (the timezone and utc plugins are only used to format the result as CST):

import dayjs from 'dayjs'
import customParseFormat from 'plugin/customParseFormat'
import timezone from 'plugin/timezone'
import utc from 'plugin/utc'

dayjs.extend(customParseFormat)
dayjs.extend(utc)
dayjs.extend(timezone)


it('Parsing is broken', () => {
  const input = '2020-12-20T15:00:00+08'
  const format = 'YYYY-MM-DD[T]HH:mm:ssZ'
  const resultDayjs = dayjs(input, format)
  expect(resultDayjs.isValid()).toBe(true)
  expect(resultDayjs.tz('Asia/Taipei').format()).toBe('2020-12-20T15:00:00+08:00')
})

Thanks for your suggestion. It work well when we applied the plugin with time format.

Show my snippet in node.js below for anyone finding a solution.

const dayjs = require('dayjs')
const customParseFormat = require('dayjs/plugin/customParseFormat')
dayjs.extend(customParseFormat)
const format = 'YYYY-MM-DD[T]HH:mm:ssZ'
console.log(`result:${dayjs('2020-12-20T15:00:00+0800', format).format()}`);
console.log(`result:${dayjs('2020-12-20T15:00:00+08', format).format()}`);