perf: replace mime-types with mrmime

[chenjiahan]

The mime-types package was replaced with mrmime which offers better performance. This change includes:

• Updating dependencies in package.json
• Modifying mime type handling logic in source files
• Updating documentation references
• Adjusting test cases to work with the new package

https://npmx.dev/compare?packages=mime-types,mrmime

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on a significant performance optimization by swapping out the existing 'mime-types' library for 'mrmime'. This change streamlines how mime types are identified and managed throughout the application, leading to more efficient operations. The update involved a comprehensive refactor across dependencies, core logic, documentation, and testing to ensure a seamless transition and maintain robust functionality.

Highlights

• Performance Improvement: The 'mime-types' package has been replaced with 'mrmime' to enhance performance, as 'mrmime' offers a faster alternative for mime type handling.
• Dependency Updates: The 'package.json' and 'pnpm-lock.yaml' files were updated to reflect the removal of 'mime-types' and the addition of 'mrmime' as a dependency.
• Mime Type Handling Logic: Core logic in 'src/index.js' and 'src/middleware.js' was modified to integrate with the 'mrmime' library, including a new utility function for content type determination and custom mime type registration.
• Documentation and Tests: Documentation in 'README.md' was updated to reference 'mrmime', and test cases in 'test/middleware.test.js' were adjusted to ensure compatibility and correct functionality with the new package.

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Changelog

• README.md
  • Updated the documentation link for mime type information from 'mime-types' to 'mrmime'.
• package.json
  • Replaced 'mime-types' with 'mrmime' in production dependencies.
  • Removed '@types/mime-types' from development dependencies.
• pnpm-lock.yaml
  • Updated the lockfile to reflect the removal of 'mime-types' and its types.
  • Added 'mrmime' and its associated resolution to the lockfile.
• src/index.js
  • Changed the import statement from 'mime-types' to destructure 'mimes' from 'mrmime'.
  • Modified the custom mime type registration logic to directly update the 'mimes' object from 'mrmime'.
• src/middleware.js
  • Replaced the 'mime-types' import with 'lookup' and 'mimes' from 'mrmime'.
  • Introduced a new 'getContentType' function to handle mime type lookups and charset appending.
  • Added 'usdz' as a custom mime type to the 'mimes' object.
  • Updated the content type header setting logic to use the new 'getContentType' function.
• test/middleware.test.js
  • Updated the import statement to use 'lookup' and 'mimes' from 'mrmime'.
  • Defined 'UTF8_CHARSET_MIME_TYPES' set for consistent charset handling in tests.
  • Added 'usdz' as a custom mime type to the 'mimes' object for testing.
  • Refactored the 'getContentTypeHeader' helper function to utilize 'mrmime.lookup' and apply charset logic.

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[gemini-code-assist]

Code Review

This pull request replaces the mime-types package with the more performant mrmime. The changes are well-implemented across the codebase, including dependency updates in package.json, logic adjustments in the source files, and documentation updates. My main feedback concerns some code duplication that was introduced between the middleware source and its test file. Consolidating the duplicated logic would improve the long-term maintainability of the code. Overall, this is a solid performance improvement.

[Copilot]

Pull request overview

Replaces the mime-types dependency with mrmime to improve MIME lookup performance while preserving expected Content-Type header behavior (including charset=utf-8 for common text/UTF-8 types) and keeping the mimeTypes override option working.

Changes:

• Swap runtime dependency from mime-types to mrmime and update lockfile.
• Introduce getContentType() in middleware to compute Content-Type values (including UTF-8 charset handling) using mrmime.lookup.
• Update tests and README references to align with mrmime, including custom mapping for .usdz.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/middleware.js	Replaces mime.contentType usage with a mrmime-based getContentType() helper and adds UTF-8 charset handling + .usdz mapping.
src/index.js	Updates mimeTypes option handling to override mrmime mappings in-place via mimes.
test/middleware.test.js	Updates test expectations and helper logic to match mrmime lookup behavior and charset rules.
package.json	Replaces mime-types with mrmime and removes @types/mime-types.
pnpm-lock.yaml	Locks mrmime@2.0.1 and removes direct mime-types importer dependency and @types/mime-types.
README.md	Updates documentation link from mime-types to mrmime.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

Comments suppressed due to low confidence (1)

src/middleware.js:723

• The inline comment says the content type can be "... or false", but getContentType() returns string | undefined and never returns false. Please update the comment to match the actual return type (or adjust the function to return false if that's a deliberate contract).

        // Only set content-type header if media type is known
        // https://tools.ietf.org/html/rfc7231#section-3.1.1.5
        if (contentType) {

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