In the browser, Javascript’s role is to add interactivity to the web page, and the API has a good surface area (even if not really pretty). People talk about the lack of standard library, but they can never say what’s missing.

https://developer.mozilla.org/en-US/docs/Web/API

The above seems fairly expansive, even if we remove all the experimental ones in the list.

I suppose we could quibble about what exactly “standard library” means, but I’m presuming we’re talking about the web (rather than, say, Node or Bun). And to me it’s fair to use it to refer to all web APIs that are widely available. Things like crypto, ArrayBuffer, TextEncoder, File and the File System Access API, Intl, the Streams API, Window.performance, etc.