CODE EXAMPLE FOR SHELL

search class in all files used

In VS Code to see all files and/or elements a css class is being used,
search the workspace with the 'Search Panel'. For example, select the
class from css file, e.g. '.btn-primary', and goto 'Edit' on menu bar:
  
 'Edit' > 'Find in Files'  or  'Cmd + Shift + F'(Mac) 

Use 'files to include' or 'files to exclude' fields to narrow search
e.g. search all html files and a 'script.js' within 'public/' folder:

  'Search': .btn-primary
		
  'files to include':  public/**/*.html,script.js