Unexpected behavior while importing npm module

Im trying to use dns2 library in my deno project:

import { Packet } from 'npm:dns2'

import { Packet } from 'npm:dns2'

And I get this error:

& deno run -A --watch src/index.ts
error: Uncaught SyntaxError: The requested module 'npm:dns2' does not provide an export named 'Packet'

& deno run -A --watch src/index.ts
error: Uncaught SyntaxError: The requested module 'npm:dns2' does not provide an export named 'Packet'

But if I import this library in a different way, then everything works:

import dns from 'npm:dns2'
console.log(dns.Packet)

import dns from 'npm:dns2'
console.log(dns.Packet)

Output:

[Function: Packet] {
  TYPE: {
...

[Function: Packet] {
  TYPE: {
...

What am I doing wrong? Deno v1.44.4

2 Replies

marvinh.•5mo ago

You're doing nothing wrong, it's a problem with the dns2 package. They only provide code in commonJS format and export a single class as the default export.

class DNS {
  // ...
}

DNS.Packet = ...
module.exports = DNS

class DNS {
  // ...
}

DNS.Packet = ...
module.exports = DNS

That class has a static Packet member, but a class member is very different from a module export. In JavaScript one cannot destructure class members in import statements.

herenicknameOP•5mo ago

Thanks. I forked this package on my github to fix some things. Am I right in thinking that I won't be able to import it locally until I load it into npm? It's pretty hard to adapt the version for deno.

Unexpected behavior while importing npm module

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