fix: fix isDayjs check logic

[iamkun]

ref: https://github.com/moment/moment/blob/develop/src/lib/moment/constructor.js#L78

isDayjs should return true in different versions of dayjs.

[codecov]

Codecov Report

Merging #2383 (0f2089d) into dev (061aa7e) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##               dev     #2383   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          183       183           
  Lines         2198      2200    +2     
  Branches       593       594    +1     
=========================================
+ Hits          2198      2200    +2     

Impacted Files	Coverage Δ
src/index.js	100.00% <100.00%> (ø)

[avand]

@iamkun I'm experiencing what I think is a bug that this ticket may resolve. When I use dayjs.isDayjs() together with a plugin like dayjs.extend(utc) and organize my code in multiple files, I get false when I expect `true. Let me demonstrate:

// utcDay.js
import dayjs from 'dayjs';
import utc from 'dayjs/plugin/utc';

function utcDay() {
  dayjs.extend(utc);
  return dayjs.utc();
}

// index.js
import utcDay from 'utcDay';

dayjs.isDayjs(utcDay()) // => false

Would the changes you made here fix this issue? And if so, when will they be released?

Update: I just pointed my package.json to GitHub (e.g., "dayjs": "https://github.com/iamkun/dayjs") and this issue went away. So it indeed seems to have resolved my issue.

[github-actions]

🎉 This PR is included in version 1.11.10 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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[jSebestyen590]

I have a problem related to this change. We have a Dayjs object that we store in location.state where it get's serialized. Upon retrieving said object we use isDayjs to check whether the object is actually of type Dayjs or if we have to parse it, something along the lines of

const maybeBrokenDayjs(obj: any) => {
  if (isDayjs(obj) {
    return obj;
  } else if (obj?.$d) {
    return dayjs(obj.$d)
  }
}

This now obviously breaks as isDayjs will suddenly yield true. While this is of course easily fixable it is a breaking change and thus quite unexpected in a Patch-Release :(