Remix doesn't import `.mjs` files, when defined without extension.

[ericfennis]

Reproduction

1. Create an .mjs file with some js
2. Import like you normally would import something, like import MyModule from "./my-module";
3. See it throws an error. "Cannot find module"

System Info

System:
    OS: macOS 14.7.1
    CPU: (12) arm64 Apple M2 Max
    Memory: 2.62 GB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 23.7.0 - ~/.nvm/versions/node/v23.7.0/bin/node
    Yarn: 1.22.22 - /opt/homebrew/bin/yarn
    npm: 10.9.2 - ~/.nvm/versions/node/v23.7.0/bin/npm
    pnpm: 9.15.3 - ~/.nvm/versions/node/v23.7.0/bin/pnpm
    bun: 1.0.25 - ~/.bun/bin/bun
  Browsers:
    Chrome: 135.0.7049.116
    Safari: 18.1
  npmPackages:
    @remix-run/dev: ^2.16.5 => 2.16.5 
    @remix-run/node: ^2.16.5 => 2.16.5 
    @remix-run/react: ^2.16.5 => 2.16.5 
    @remix-run/serve: ^2.16.5 => 2.16.5 
    vite: ^6.0.0 => 6.3.4

Used Package Manager

pnpm

Expected Behavior

Remix should import .mjs files if it won't find a .js file.

Actual Behavior

Throws error: "Cannot find module"

[github-actions]

Thank you for opening this issue, and our apologies we haven't gotten around to it yet!

With the release of React Router v7 we are sun-setting continued development/maintenance on Remix v2. If you have not already upgraded to React Router v7, we recommend you do so. We've tried to make the upgrade process as smooth as possible with our Future Flags. We are now in the process of cleaning up outdated issues and pull requests to improve the overall hygiene of our repositories.

We plan to continue to address 2 types of issues in Remix v2:

• Bugs that pose security concerns
• Bugs that prevent upgrading to React Router v7

If you believe this issue meets one of those criteria, please respond or create a new issue.

For all other issues, ongoing maintenance will be happening in React Router v7, so:

• If this is a bug, please reopen this issue in that repo with a new minimal reproduction against v7
• If this is a feature request, please open a new Proposal Discussion in React Router, and if it gets enough community support it can be considered for implementation

If you have any questions you can always reach out on Discord. Thanks again for providing feedback and helping us make our framework even better!