Vue.js 'import' does not work within external js file

Question

Let me try to explain...

I have an utils.js file which does not work:

import dayjs from 'dayjs'; //https://github.com/iamkun/dayjs
exports.utils = (function() {
 someDateFunction() {
 ...some dayjs function calls ....
 }
})();

(As stated by an answering person thta it needs to be module.exports - well it does not matter. I have other source files where it works either way - with or without prenoted module..)

When declaring the first line with the import statement vue-cli seems to properly compile. no error is shown. Running in the browser shows:

Uncaught ReferenceError: exports is not defined
 at eval (utils.js?2f14:3)
 at Module../src/assets/js/utils.js (app.js:1541)
 at __webpack_require__ (app.js:849)
 at fn (app.js:151)
 ...

It do include/import this utils.jsfile by noting
const { utils } = require("@/assets/js/utils.js");

Why is it not allowed to import in the file?
If you need informations about versions I run let me know and also let me know what commands will show the demanded information (running on macos).

I already searched the web. the problem seems to be known in the past. There is some clues solving it with typescript or vue js.

Nothing works for me. I must not be the first one stumbling over issues like that, am I? Any help appreciated.

References:
https://stackoverflow.com/a/55334703/845117

My dependencies in package.json

"dependencies": {
 "axios": "^0.21.1",
 "bootstrap": "^4.5.3",
 "bootstrap-vue": "^2.18.0",
 "core-js": "^3.6.5",
 "cropperjs": "^1.5.9",
 "dayjs": "^1.9.6",
 "vue": "^2.6.12"
},

• tuhin47: delete node_modules and install again
• tony19: I can't reproduce this error in a default Vue CLI scaffolded project, using the code in question. Can you link to a GitHub repo that reproduces the problem?
• Dirk Schumacher: @tuhin47 your proposal did not work. I also fully set up the project with vue-cli.

Answer 1

One solution I just found:

instead of

import dayjs from 'dayjs';

I use

const dayjs = require('dayjs');

That works. I figured it by by reading https://www.educba.com/require-vs-import/
I cannot really argue why it works the one and not the other way. (Since I am not a native speaker I just understood 15% of the article. And I have not yet tried tuhin47's proposal)

Answer 2

It says exports does not exist because it should be module.exports = <your function definition>

• Dirk Schumacher: This does not help my issue. Using the setup without import works faultlessly. Both statements would be accepted by vue-cli and the browser - with or without writing a leading 'module.'