Beyond that, the breakdown is:
- .ts source files: 25MB
- Sourcemaps: 23MB
- Markdown: 15MB
- JSON: 10MB
It also looks like there's a 12MB Linux binary that was only in there as a publishing accident for the `user-event` library that has since been resolved ( https://github.com/testing-library/user-event/issues/266 ).
Or, take Redux Toolkit, which I maintain. If you look at https://unpkg.com/browse/@reduxjs/toolkit@1.6.2/ , the published package for our current version, it adds up to about 10MB on disk. But, that's because we ship three separate entry points (RTK core, RTK Query UI-agnostic core, RTK Query with React-specific additions), and for each entry point we compile the code to multiple file formats (CommonJS, ESM legacy, ESM modern, ESM with "dev" and "prod" already built in, UMD dev, UMD production), and each of those has sourcemaps. The actual amount of code that ends up in your bundle is about 20KB min+gz.
So, it's a combination of many things: TS itself is big, libraries typically publish packages containing both the original source code plus multiple build artifacts to run in different environments, and packages also include various metadata and other files as well.
I'm not saying this is necessarily a _good_ situation :) Goodness knows that JS dependency trees _should_ be much smaller. But there's a lot more nuance to it than just "245MB of code wut lol".
Obviously I have no idea what your app is, I have found very frequently it is not reasonable to have blobs of similar sizes (especially if text content waits for some front end framework to download/initialize).