Why are there separate async methods for shortcodes, filters?

[luwes]

Just wondering if there is a reason this has to be explicit? e.g. addNunjucksAsyncFilter()

Wouldn't it be possible to derive this from the async keyword that is defined before the callback?
Seems a nicer devex, less API's.

For example addNunjucksFilter('myFilter', async () => {})

See here for detecting an async function, a lot of test runners use this technique; AVA, Tape, etc
https://stackoverflow.com/a/38510353/268820

[dz4k]

One reason I can think of: not all async functions are async functions, one could also implement asynchrony with just new Promise() and .then().

Secondly, the SO link you included mentions that some transpilers might transform async functions to normal ones. I'm not sure how many people transpile their .eleventy.js but I'm sure there are some.

[zachleat]

Took your suggestion!

Read more here: https://www.11ty.dev/docs/filters/#asynchronous-universal-filters