gulpfile.js

var gulp = require('gulp');
var gutil = require('gulp-util');
var bower = require('bower');
var concat = require('gulp-concat');
var sass = require('gulp-sass')(require('sass'));
var cleanCss = require('gulp-clean-css');
var rename = require('gulp-rename');
var sh = require('shelljs');

var paths = {
  sass: ['./scss/**/*.scss'],
};

gulp.task('sass', function(done) {
  gulp.src('./scss/ionic.app.scss')
    .pipe(sass())
    .on('error', sass.logError)
    .pipe(gulp.dest('./www/css/'))
    .pipe(cleanCss({
      keepSpecialComments: 0
    }))
    .pipe(rename({ extname: '.min.css' }))
    .pipe(gulp.dest('./www/css/'))
    .on('end', done);
});

gulp.task('watch', function() {
  gulp.watch(paths.sass, gulp.series('sass'));
});

// gulp.task('install', ['git-check'], function() {
//   return bower.commands.install()
//     .on('log', function(data) {
//       gutil.log('bower', gutil.colors.cyan(data.id), data.message);
//     });
// });
//
// gulp.task('git-check', function(done) {
//   if (!sh.which('git')) {
//     console.log(
//       '  ' + gutil.colors.red('Git is not installed.'),
//       '\n  Git, the version control system, is required to download Ionic.',
//       '\n  Download git here:', gutil.colors.cyan('http://git-scm.com/downloads') + '.',
//       '\n  Once git is installed, run \'' + gutil.colors.cyan('gulp install') + '\' again.'
//     );
//     process.exit(1);
//   }
//   done();
// });


 gulp.task('watch', function() {
    gulp.watch(paths.sass, ['sass']);
  });

gulp.task('default', gulp.series('sass','watch'));