An AppleScript to hide the file extensions of the files you’ve selected in Finder: I created a Quick Action in Automator, added a single “Run AppleScript” action, pasted in the following script, saved under the “Hide Extensions” name, and there you go.

  tell application "Finder"
    set theFiles to selection
    repeat with theFile in theFiles
      set extension hidden of theFile to true
    end repeat
  end tell

As a Quick Action, you can run it:

• From the Quick Action button on the Finder’s toolbar
• On the Services menu when you right-click the selected files
• From a button if you have the Preview Window (Mojave) open

You can also run it from the Macbook Pro touch bar, I believe. The fun thing about AppleScripts is that after some familiarity, you start to feel like just about any application you use is scriptable like Emacs is. Kind of. I’ve got one that acts as a Dock icon, lets me open a new finder window. Normally, clicking the finder icon will bring up an existing one. Another resets BBEdit for a distraction free writing configuration. Auto-switch to dark mode via keyboard command. Move the dock to left, right or bottom via a keyboard command. Fun stuff.

Admittedly, I pretty much web-search for just about anything I want to do because the object models are super opaque (to me).