Gulp 3 gulpfile.js config

gulpfile.js

/*global require*/
"use strict";

var gulp = require('gulp'),
    gulpCopy = require('gulp-copy'),
    path = require('path'),
    data = require('gulp-data'),
    // pug = require('gulp-pug'),
    twig = require('gulp-twig'), // Decided to use twig, because already familiar with it
    prefix = require('gulp-autoprefixer'),
    sass = require('gulp-sass'),
    plumber = require('gulp-plumber'),	
    concat = require('gulp-concat'),
    sourcemaps = require('gulp-sourcemaps'),
    browserSync = require('browser-sync'),
    fs = require('fs'),
    del = require('del');

/*
 * Directories here
 */
var paths = {
  src: './src/',
  build: './build/',
  sass: './scss/',
  css: './build/assets/css/',
  data: './client/data/',
  assets: './src/assets/'
};

/**
 * Clean assets directory
 */
gulp.task('clean', function () {
    return del(['build/assets/**/*', '!build/assets/js/*.*']);
});

/**
 * Copy assets directory
 */
gulp.task('copy-assets', function () {
    return gulp
    .src(['./src/assets/**/*', '!./src/assets/js/*.*'])
    .pipe(gulpCopy(paths.build + 'assets', { prefix: 2 }))
    .pipe(browserSync.reload({
	  stream: true
  	})
    );
});

/**
 * Compile .twig files and pass in data from json file
 * matching file name. index.twig - index.twig.json
 */
gulp.task('twig', function () {
  return gulp.src(['./client/templates/*.twig'])
  // Stay live and reload on error
  .pipe(plumber({
	handleError: function (err) {
		console.log(err);
		this.emit('end');
	}
  }))
  // Load template pages json data
  .pipe(data(function (file) {
		  return JSON.parse(fs.readFileSync(paths.data + path.basename(file.path) + '.json'));		
	}))
  // Load default json data
  .pipe(data(function () {
	    return JSON.parse(fs.readFileSync(paths.data + path.basename('default.twig.json')));
	}))
	.on('error', function (err) {
            process.stderr.write(err.message + '\n');
            this.emit('end');
        })
  .pipe(twig())
  .on('error', function (err) {
        process.stderr.write(err.message + '\n');
        this.emit('end');
  })
  .pipe(gulp.dest(paths.build))
  .pipe(browserSync.reload({
	stream: true
   }));
});

/**
 * Recompile .twig files and live reload the browser
 */
gulp.task('rebuild', ['twig'], function () {
  // BrowserSync Reload
  browserSync.reload();
});

/**
 * Wait for twig, js and sass tasks, then launch the browser-sync Server
 */
gulp.task('browser-sync', ['sass', 'twig', 'js'], function () {
  browserSync({
    server: {
      baseDir: paths.build
    },
    notify: false,
    browser:"google chrome"
  });
});

/**
 * Compile .scss files into build css directory With autoprefixer no
 * need for vendor prefixes then live reload the browser.
 */
gulp.task('sass', function () {
  return gulp.src(paths.sass + 'main.scss')
    .pipe(sourcemaps.init())
    // Stay live and reload on error 
    .pipe(plumber({
		  handleError: function (err) {
			  console.log(err);
			  this.emit('end');
		 }
    }))
    .pipe(sass({
		  includePaths: [paths.sass, paths.sass + 'decoroom/'],
		  outputStyle: 'expanded'
		})
		.on('error', function (err) {
			console.log(err.message);
			// sass.logError
			this.emit('end');
		})
    )
    .pipe(prefix(['last 15 versions','> 1%','ie 8','ie 7','iOS >= 9','Safari >= 9','Android >= 4.4','Opera >= 30'], {
      cascade: true
    }))	
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest(paths.css));
});

/**
 * Compile .js files into build js directory With app.min.js
 */
gulp.task('js', function(){
    return gulp.src('src/assets/js/script.js')
    .pipe(sourcemaps.init())
    .pipe(concat('script.js'))
       	.on('error', function (err) {
            console.log(err.toString());
            this.emit('end');
        })
    .pipe(browserSync.reload({
	stream: true
    }))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest(paths.build + 'assets/js'));
});

/**
 * Watch scss files for changes & recompile
 * Watch .twig files run twig-rebuild then reload BrowserSync
 */
gulp.task('watch', function () {
  // Script JS
  gulp.watch(paths.assets + 'js/script.js', ['js', browserSync.reload]);
  // SCSS files or main.scss
  gulp.watch([paths.sass + 'vendors/*.scss', paths.sass + '*.scss'], ['sass', browserSync.reload]);
  gulp.watch(['client/templates/**/*.twig','client/data/*.twig.json'], {cwd:'./'}, ['rebuild']);
  // Assets Watch and copy to build in some file changes
  gulp.watch(['src/assets/**/*', '!src/assets/js/*.js', '!src/assets/css/*.css'], ['copy-assets', browserSync.reload]);
});

// Build task compile sass and twig.
gulp.task('build', [ 'clean','sass', 'js','twig','copy-assets']);

/**
 * Default task, running just `gulp` will compile the sass,
 * compile the project site, launch BrowserSync then watch
 * files for changes
 */
gulp.task('default', ['browser-sync', 'watch']);