Change icons for file types via Registry

I want to change the icons for JavaScript [.js] file types without the use of external software.

1. One online guide suggested to:
   1. Note the value [Applications\Code.exe] of the below key; however, as far as I know, this only refers to the application this file type is opened with by default:

      HKCU\Software\Microsoft\Windows\CurrentVersion\.js\ProgID

   2. Change the icon path of the below key, which would change all icons for file types opened with VS Code:

      HKCR\Applications\Code.exe\DefaultIcon

2. Another guide suggested to:
   1. Create subkey HKCR\.js\DefaultIcon, with value type REG_SZ, and a data value of the full path to the icon, with how many sizes this icon file contains separated by a comma (didn't work):
      

How do I assign a custom icon for a file type that overwrites the default icon of the app that opens this file type by default?

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