title: Ignore files for the npm build
body: <p>When I build my React app using  <code>npm run-script build</code> there are a folder and a file that I don't want to be there.
  Is there a way to ignore the file and the folder during the npm run-script build?
  I know there are the .gitignore and the .npmignore but there are used to ignore the files only for the publication (not the build).</p>
  
  <p>Thank you.</p>