Is there a working example for fetch and php? [closed]

I need to use fetch js (POST request method). It is possible to use json or "form data" for body. And also in the php file I need to get $_POST with the sent data.
I looked at many examples on sites and tried to repeat them, but I never managed to get the data in the php file. Here on this page there is an example, but an empty array is displayed in the php file.
Maybe something has changed in fetch and that's why I can't repeat the examples. Does anyone know a link to a working example?

source https://stackoverflow.com/questions/76017882/is-there-a-working-example-for-fetch-and-php