clean.js

// Styles
gulp.task('styles', function() {
    return gulp.src(config.sources.styles)
        .pipe(sass({ errLogToConsole: true, outputStyle: 'expanded' }))
        .pipe(prefix('last 2 version', 'safari 5', 'ie 8', 'ie 9', 'opera 12.1', 'ios 6', 'android 4'))
        .pipe(gulpif(isProduction, mincss({ keepSpecialComments: 0 })))
        .pipe(header(banner))
        .pipe(gulp.dest(config.output.styles))
        .pipe(reload(server));
});

// Scripts
gulp.task('scripts', function() {
    return gulp.src(config.sources.scripts)
        .pipe(jshint('.jshintrc'))
        .pipe(jshint.reporter(stylish))
        .pipe(concat('main.js'))
        .pipe(gulpif(isProduction, uglify()))
        .pipe(header(banner))
        .pipe(gulp.dest(config.output.scripts))
        .pipe(reload(server))
});

// Images
gulp.task('images', function() {
    return gulp.src(config.sources.images)
        .pipe(imagemin({
            optimizationLevel: 5,
            progressive: true,
            interlaced: true
        }))
        .pipe(gulp.dest(config.output.images))
        .pipe(reload(server))
});

// Clean assets
gulp.task('clean', function(cb) {
    return gulp.src('./src/assets', {read: false})
        .pipe(clean());
    cb()
});


// The Gulp 3.5 way, no gulp.run(); 
// No guarantee clean will be complete
gulp.task('build', ['clean', 'styles', 'scripts', 'images']);

// The pre-Gulp 3.5 way
// Clean will be complete beforehand
gulp.task('build', ['clean'], function() {
    gulp.run('styles', 'scripts', 'images');
})

/**
 * What would be considered best practice for ensuring clean is fully complete
 * and finished before running other tasks? I want to be able to run `styles`, `scripts`, `images`
 * without depending on `clean` — I only want to clean when then `build` task is executed.
 */