CODEWITHSUNDEEP
javascriptnode.js
Aleksandr Krasikov
Aleksandr Krasikov

Reputation: 59

node.js 13 - import is not working properly

$ node --version v13.8.0

Let's create three files:

// package.json
{
  "type": "module"
}

// foobar.js 
function foo() { console.log('foo') }
export default {foo}

// index.js 
import Foo from './foobar.js';
Foo.foo();

Run index.js

$ node index.js
(node:22768) ExperimentalWarning: The ESM module loader is experimental.
foo

All working.

And now changing './foobar.js'; to './foobar';

// index.js 
import Foo from './foobar';
Foo.foo();

And we get an error!

(node:22946) ExperimentalWarning: The ESM module loader is experimental.
internal/modules/esm/resolve.js:58
  let url = moduleWrapResolve(specifier, parentURL);
            ^
Error: Cannot find module /foobar imported from /index.js

There is no other files in directory.

Why does it happens? Why import without extension doesn't work?

UPDATE: https://nodejs.org/api/esm.html

package.json "type" field

Files ending with .js or lacking any extension will be loaded as ES modules when the nearest parent package.json file contains a top-level field "type" with a value of "module".

So './foobar' must work.

UPDATE 2:

I believe what the documentation call "extensionless files" are literaly files without extensions, not files imported without extensions.

For example, if you import your file with import Foo from './foobar';, and you file is called foobar without the .js extension, it will work fine.

Thanks to @Seblor

Upvotes: 3

Views: 2607

Answers (1)

Seblor
Seblor

Reputation: 7136

Looking at the documentation, in the category Differences Between ES Modules and CommonJS, and more precisely at the "Mandatory file extensions" section, it says that the .js file extension must be present to make the import work :

A file extension must be provided when using the import keyword. Directory indexes (e.g. './startup/index.js') must also be fully specified.

This behavior matches how import behaves in browser environments, assuming a typically configured server.

I am not sure why your last question is about the import without extention not working anymore. I guess you have been working at some point with a transpiler like babel that will resolve the files without the extensions.

Edit :

I believe what the documentation call "extensionless files" are literaly files without extensions, not files imported without extensions.

For example, if you import your file with import Foo from './foobar';, and you file is called foobar without the .js extension, it will work fine.

Upvotes: 6

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