Introduction to Gulp.js 4: Creating CSS with Sass (and Compass)

Stefan Imhoff

This is the 4th part of my series Introduction to Gulp.js. Today I will show how to use Sass (and Compass if you want) to create CSS files. Furthermore I will add vendor prefixes with Autoprefixer and create Source Maps for easier debugging of the Sass files.

Sarah Palin holding a Big Gulp

Gage Skidmore, Sarah Palin


Sass and Autoprefixer

I use Sass as preprocessor for my CSS files. If you like to use Compass, you just have to set an option for this task.

Go ahead and install the npm modules needed:

$ npm install --save-dev gulp-plumber@1.0.1 gulp-ruby-sass@2.0.4 gulp-filter@3.0.1 gulp-changed@1.0.0 gulp-autoprefixer@3.0.2 gulp-sourcemaps@1.6.0

That’s a lot, but this task will do a lot.

sass: {
  src:  srcAssets + '/scss/**/*.{sass,scss}',
  dest: developmentAssets + '/css',
  options: {
    noCache: true,
    compass: false,
    bundleExec: true,
    sourcemap: true
  }
},
autoprefixer: {
  browsers: [
    'last 2 versions',
    'safari 5',
    'ie 8',
    'ie 9',
    'opera 12.1',
    'ios 6',
    'android 4'
  ],
  cascade: true
}
gulp/config.js
var gulp         = require('gulp');
var plumber      = require('gulp-plumber');
var browsersync  = require('browser-sync');
var sass         = require('gulp-ruby-sass');
var gulpFilter   = require('gulp-filter');
var autoprefixer = require('gulp-autoprefixer');
var sourcemaps   = require('gulp-sourcemaps');
var config       = require('../../config');

/**
 * Generate CSS from SCSS
 * Build sourcemaps
 */
gulp.task('sass', function() {
  var sassConfig = config.sass.options;

  sassConfig.onError = browsersync.notify;

  // Don’t write sourcemaps of sourcemaps
  var filter = gulpFilter(['*.css', '!*.map'], { restore: true });

  browsersync.notify('Compiling Sass');

  return sass(config.sass.src, sassConfig)
    .pipe(plumber())
    .pipe(sourcemaps.init())
    .pipe(autoprefixer(config.autoprefixer))
    .pipe(filter) // Don’t write sourcemaps of sourcemaps
    .pipe(sourcemaps.write('.', { includeContent: false, sourceRoot: 'app/_assets/scss' }))
    .pipe(filter.restore) // Restore original files
    .pipe(gulp.dest(config.sass.dest));
});
gulp/task/development/sass.js

I load all my files with the suffix of *.sass or *.scss. First I pipe the files through Plumber. It will keep Gulp.js running if I create a syntax error in one of my files. It would normally just crash with an error. The next step creates the CSS files, running the sass command. I create source maps and finally put the CSS files to it’s destination.

And I run the CSS files through Autoprefixer, which will add vendor prefixes. I used the Mixins of Compass a long time, but stopped now and write pure CSS. All vendor prefixes are added later for the browsers I want to support.

You might have guessed: If you want to use Compass, just set the option compass to true.

Source Code

Conclusion

This concludes the 4th part of my series Introduction to Gulp.js. We learned how to keep Gulp.js running, even when we produce errors, how to preprocess SCSS files with Sass, create Source Maps and add vendor prefixes to the CSS files.

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