gulpfile.js

var gutil = require('gulp-util');

...


// Lint JavaScript
gulp.task('lint', function() {
  var requiredFiles = ['.jscsrc', '.jshintrc', 'weasel.ball'];
  requiredFiles.forEach(function(file) {
    try {
      fs.statSync(file)
    } catch(err) {
      throw new gutil.PluginError({
        plugin: 'lint',
        message: 'Missing required file: ' + file
      });
    }
  });

  return gulp.src([
      'app/scripts/**/*.js',
      'app/elements/**/*.js',
      'app/elements/**/*.html',
      'gulpfile.js'
    ])
    .pipe(reload({
      stream: true,
      once: true
    }))

  // JSCS has not yet a extract option
  .pipe($.if('*.html', $.htmlExtract()))
  .pipe($.jshint())
  .pipe($.jscs())
  .pipe($.jscsStylish.combineWithHintResults())
  .pipe($.jshint.reporter('jshint-stylish'))
  .pipe($.if(!browserSync.active, $.jshint.reporter('fail')));
});