'How to format all JavaScript files in an Eclipse project at one time?

I created a custom js-formatter in Eclipse and now I want to format all .js files.

I found this answer for .java files, but I don't know how to do it for .js files.
When I tried "Source->Format" all my .xml files were formatted, but none of the .js files were.

I guess it depends on the type of Eclipse project, which files are formatted using "Source->Format"? I'm looking for a way to do this without being dependent on the type of project.
I also checked if JavaScript is checked in "Files->Properties->Project Facets" but it already is.

My Eclipse IDE is called:
Eclipse IDE for Enterprise Java Developers.
Version: 2019-03 (4.11.0)



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