gulpfile.js

var gulp = require('gulp');
var plumber = require('gulp-plumber');
var sass = require('gulp-sass');
var watch = require('gulp-watch');
var concat = require('gulp-concat');
var gulpif = require('gulp-if');
var cssnano = require('gulp-cssnano');
var imagemin = require('gulp-imagemin');
var uglify = require('gulp-uglify');
var rimraf = require('gulp-rimraf');



var args = require('yargs')
    .default('production', false)
    .alias('p', 'production')
    .argv;

gulp.task('styles', function () {
    var isProduction = args.production;
    return gulp.src('sources/sass/**/*.scss')
        .pipe(plumber())
        .pipe(sass())
        .pipe(gulpif(isProduction, cssnano({
            discardComments: {removeAll: true},
            browsers: [
                "> 1%",
                "last 2 versions"
            ]
        })))
        .pipe(gulp.dest('css'));
});

gulp.task('scripts', function () {
    var isProduction = args.production;
    return gulp.src([
        'node_modules/jquery/dist/jquery.slim.min.js',
        'node_modules/bootstrap/dist/js/bootstrap.js',
        'sources/js/*.js'
    ])
    .pipe(concat('theme.js'))
    .pipe(gulpif(isProduction, uglify()))
    .pipe(gulp.dest('js'));

})

gulp.task('images', function(){
    var isProduction = args.production;
    return gulp.src('sources/img/**/*.{jpg,png,gif}')
        .pipe(gulpif(isProduction,imagemin({
            optimizationLevel: 7,
            progressive: true,
            interlaced: true
        })))
        .pipe(gulp.dest('images'))
});

gulp.task('fonts', function () {
    gulp.src('node_modules/font-awesome/fonts/**/*.{ttf,woff,woff2,eof,svg}')
        .pipe(gulp.dest('fonts'));
})

gulp.task('clean:css', function() {
    return gulp.src('css/*.css', { read: false })
        .pipe(rimraf());
});

gulp.task('clean:images', function() {
    return gulp.src('images/*.*', { read: false })
        .pipe(rimraf());
});

gulp.task('clean',['clean:images','clean:css']) // Limpa todas img e css
gulp.task('default', ['styles','images','scripts']);

gulp.task('watch', function () {
    var onChange = function(event){
        console.log('File ' + event.path + ' was ' + event.type + ', running tasks...');
    }

    gulp.watch('sources/sass/**/*.scss', ['styles']).on('change', onChange);
    gulp.watch('sources/js/**/*.js', ['scripts']).on('change', onChange);
    gulp.watch('sources/img/**/*.{jpg,png,gif}', ['images']).on('change', onChange);
});