Same for JetBrains IDEs.

I hate inlay hints because they usually add unnecessary clutter. I prefer to use languages that allow you to add them manually when needed.

How is this done for js?

As far as I know it is not a native feature, but inline hints for parameter names can be added with a VSCode extension called "Inline Parameters for VSCode": https://marketplace.visualstudio.com/items?itemName=liamhamm...

The only languages it supports are JavaScript, TypeScript, PHP, and Lua. I can confirm that it works for JavaScript and TypeScript, I haven't tried the other two.

A similar extension named "Inline Parameters Extended for VSCode" supports a different set of languages: Golang, Java, Lua, PHP, and Python. It seems to be a fork of the aforementioned.