Cannot find module 'dayjs/plugin/timezone' in sub-module

Describe the bug Similar to #1135, getting Cannot find module 'dayjs/plugin/timezone' from 'node_modules/my-module' when importing my module from elsewhere and trying to run tests.

The plugin works properly within the code where it’s used, but this issue appears when importing it as node_module.

Expected behavior Able to import dayjs plugins and use them in code used as a sub-module.

Usage in sub-module:

import dayjs from 'dayjs';
import customParseFormat from 'dayjs/plugin/customParseFormat';
import dayjsIsBetween from 'dayjs/plugin/isBetween';
import utc from 'dayjs/plugin/utc';
import timezone from 'dayjs/plugin/timezone';
dayjs.extend(customParseFormat);
dayjs.extend(dayjsIsBetween);
dayjs.extend(utc);
dayjs.extend(timezone);

Information

• Day.js Version: v1.9.4
• OS: Mac
• Browser Terminal

[bartosjiri]

I had a similar problem when compiling a production build of a SvelteKit app. The solution, as console error has suggested, was to add the .js extension to the import path:

Example: import timezone from 'dayjs/plugin/timezone'; -> import timezone from 'dayjs/plugin/timezone.js';

[spsaucier-bakkt]

That’s a good question 🤔 I wrote that very vaguely, and I don’t remember what I meant.