import chalk from 'chalk' ; import detectPort from 'detect-port' ; const port = process . env . PORT || '1212' ; detectPort ( port , ( err , availablePort ) => { if ( port !== String ( availablePort ) ) { throw new Error ( chalk . whiteBright . bgRed . bold ( `Port "${ port }" on "localhost" is already in use. Please use another port. ex: PORT=4343 yarn dev` ) ) ; } else { process . exit ( 0 ) ; } } ) ;