gulpfile.ts

import * as gulp from 'gulp';
import * as autoprefixer from 'gulp-autoprefixer';
import * as cssGlobbing from 'gulp-css-globbing';
import * as sass from 'gulp-sass';
import * as template from 'gulp-template';

import { join } from 'path';
import { argv } from 'yargs';


const AUTOPREFIXER_BROWSERS = [
  'ie >= 11',
  'ie_mob >= 11',
  'ff >= 30',
  'chrome >= 34',
  'safari >= 7',
  'opera >= 23',
  'ios >= 7',
  'android >= 4.4',
  'bb >= 10'
];

// --------------
// Build SASS
gulp.task('build.sass', done => {
  const app_cdn = argv.deployUrl ? argv.deployUrl: '';
  gulp.src(join('./src', '**', '*.scss'))
    .pipe(cssGlobbing({  extensions: ['.scss'] }))
    .pipe(sass({
      includePaths:[join('./src', 'stylesheets')],
      style: 'compressed'
    }).on('error', sass.logError))
    .pipe(autoprefixer(AUTOPREFIXER_BROWSERS))
    .pipe(template({
      'APP_CDN': app_cdn,
    }))
    .pipe(gulp.dest('./.styles'))
    .on('end', () => {
      gulp.src('./.styles/stylesheets/main.css')
        .pipe(gulp.dest('./src'))
        .on('end', done);
    });
});