Gulpfile v2

gulpfile.babel.js

gulp.task('assets:dev', gulp.series('styles:dev', 'javascript:dev', 'fonts', 'images'));
gulp.task('assets', gulp.series('styles', 'javascript', 'fonts', 'images'));

// Default task, run when just writing 'gulp' in the terminal
gulp.task('default', gulp.series(
      gulp.series('assets:dev'),
      gulp.series('inject:head:dev', 'inject:footer:dev'),
      gulp.series('jekyll:dev'),
      gulp.series('serve')
));

gulp.task('build', gulp.series(
      gulp.series('assets'),
      gulp.series('inject:head', 'inject:footer'),
      gulp.series('jekyll:prod')
));