gulpfile.js

'use strict';

var gulp = require('gulp');
var sass = require('gulp-sass');
var rename = require('gulp-rename');
var gulpif = require('gulp-if');
var notify = require("gulp-notify");
var gulpignore = require('gulp-if');
var sourcemaps = require('gulp-sourcemaps');
var plumber      = require('gulp-plumber');
var uglifycss    = require('gulp-uglifycss');
var uglify    = require('gulp-uglify');
var imagemin = require('gulp-imagemin');
var pngquant = require('imagemin-pngquant');
var imageminJpegRecompress = require('imagemin-jpeg-recompress');

var reportError = function (error) {
    notify({
        title: "There's an error",
        message: 'Check the console for more details.'
    }).write(error);
    console.log(error.toString());
    this.emit('end');
}

gulp.task('sass', function () {
    return gulp.src(['src/sass/**/*.scss', "!src/sass/**/_*.scss"])
            .pipe(plumber())
            .pipe(sourcemaps.init())
            .pipe(sass({
                errLogToConsole: true,
                //outputStyle: 'compressed',
                outputStyle: 'compact',
                // outputStyle: 'nested',
                // outputStyle: 'expanded',
                precision: 10
            }).on('error', reportError))
            .pipe(sourcemaps.write())
            .pipe(uglifycss())
            .pipe(gulp.dest('css'));
});

gulp.task('img', function () {
    return gulp.src('src/images/**/*')
            .pipe(imagemin({
                progressive: true,
                svgoPlugins: [{removeViewBox: false}],
                use: [pngquant(), imageminJpegRecompress({loops: 3, min: 80})]
            }))
            .pipe(gulp.dest('images'));

});

gulp.task('js', function () {
    return gulp.src('src/js/**/*.js')
            .pipe(uglify())
            .pipe(gulp.dest('js'));

});

gulp.task('watch', function() {

  gulp.watch('src/sass/**/*.scss', ['sass']);

  gulp.watch('src/js/**/*.js', ['js']);

  gulp.watch('src/images/**/*', ['img']);

});

gulp.task('default',['sass','js','img']);