My gulp setup. https://gomakethings.com/how-i-setup-my-vanilla-javascript-projects/

gulpfile.js

/**
 * Settings
 */

var settings = {
	scripts: true,		// Turn on/off script tasks
	polyfills: true,	// Turn on/off polyfill tasks
	styles: false,		// Turn on/off style tasks
	svgs: false,		// Turn on/off SVG tasks
	static: false,		// Turn on/off static file copying
	docs: true,			// Turn on/off documentation generation
	deploy: true,		// Turn on/off all deployment tasks
	cacheBust: false,	// Turn on/off cache busting (adds a version number to minified files)
};


/**
 * Gulp Packages
 */

// General
var gulp = require('gulp');
var fs = require('fs');
var del = require('del');
var exec = require('child_process').exec;
var lazypipe = require('lazypipe');
var plumber = require('gulp-plumber');
var flatten = require('gulp-flatten');
var tap = require('gulp-tap');
var rename = require('gulp-rename');
var header = require('gulp-header');
var footer = require('gulp-footer');
var watch = require('gulp-watch');
var livereload = require('gulp-livereload');
var package = require('./package.json');

// Scripts
var jshint = settings.scripts ? require('gulp-jshint') : null;
var stylish = settings.scripts ? require('jshint-stylish') : null;
var concat = settings.scripts ? require('gulp-concat') : null;
var uglify = settings.scripts ? require('gulp-uglify') : null;
var optimizejs = settings.scripts ? require('gulp-optimize-js') : null;

// Styles
var sass = settings.styles ? require('gulp-sass') : null;
var prefix = settings.styles ? require('gulp-autoprefixer') : null;
var minify = settings.styles ? require('gulp-cssnano') : null;

// SVGs
var svgmin = settings.svgs ? require('gulp-svgmin') : null;
var svgstore = settings.svgs ? require('gulp-svgstore') : null;

// Docs
var markdown = settings.docs ? require('gulp-markdown') : null;
var fileinclude = settings.docs ? require('gulp-file-include') : null;


/**
 * Paths to project folders
 */

var paths = {
	input: 'src/**/*',
	output: 'dist/',
	scripts: {
		input: 'src/js/*',
		polyfills: '!src/js/*.polyfill.js',
		output: 'dist/'
	},
	styles: {
		input: 'src/sass/**/*.{scss,sass}',
		output: 'dist/css/'
	},
	svgs: {
		input: 'src/svg/*',
		output: 'dist/svg/'
	},
	static: {
		input: 'src/static/*',
		output: 'dist/'
	},
	docs: {
		input: 'src/docs/*.{html,md,markdown}',
		output: 'docs/',
		templates: 'src/docs/_templates/',
		assets: 'src/docs/assets/**'
	}
};


/**
 * Template for banner to add to file headers
 */

var banner = {
	full :
		'/*!\n' +
		' * <%= package.name %> v<%= package.version %>: <%= package.description %>\n' +
		' * (c) ' + new Date().getFullYear() + ' <%= package.author.name %>\n' +
		' * <%= package.license %> License\n' +
		' * <%= package.repository.url %>\n' +
		' * Open Source Credits: <%= package.openSource.credits %>\n' +
		' */\n\n',
	min :
		'/*!' +
		' <%= package.name %> v<%= package.version %>' +
		' | (c) ' + new Date().getFullYear() + ' <%= package.author.name %>' +
		' | <%= package.license %> License' +
		' | <%= package.repository.url %>' +
		' | Open Source Credits: <%= package.openSource.credits %>' +
		' */\n'
};


/**
 * File Version
 */

var fileVersion = settings.cacheBust ? '.' + package.version : '';


/**
 * Gulp Tasks
 */

var jsTasks = lazypipe()
	.pipe(header, banner.full, { package : package })
	.pipe(optimizejs)
	.pipe(gulp.dest, paths.scripts.output)
	.pipe(rename, { suffix: '.min' + fileVersion })
	.pipe(uglify)
	.pipe(optimizejs)
	.pipe(header, banner.min, { package : package })
	.pipe(gulp.dest, paths.scripts.output);

// Lint, minify, and concatenate scripts
gulp.task('build:scripts', ['clean:dist'], function() {
	if (!settings.scripts) return;

	return gulp.src([paths.scripts.input, paths.scripts.polyfills])
		.pipe(plumber())
		.pipe(tap(function (file, t) {
			if (file.isDirectory()) {
				var name = file.relative + '.js';
				return gulp.src(file.path + '/*.js')
					.pipe(concat(name))
					.pipe(jsTasks());
			}
		}))
		.pipe(jsTasks());
});

// Create scripts with polyfills
gulp.task('build:polyfills', ['clean:dist'], function() {
	if (!settings.polyfills) return;

	return gulp.src(paths.scripts.input)
		.pipe(plumber())
		.pipe(concat(package.name + '.js'))
		.pipe(rename({
			suffix: ".polyfills"
		}))
		.pipe(jsTasks());
});

// Process, lint, and minify Sass files
gulp.task('build:styles', ['clean:dist'], function() {
	if (!settings.styles) return;

	return gulp.src(paths.styles.input)
		.pipe(plumber())
		.pipe(sass({
			outputStyle: 'expanded',
			sourceComments: true
		}))
		.pipe(flatten())
		.pipe(prefix({
			browsers: ['last 2 version', '> 1%'],
			cascade: true,
			remove: true
		}))
		.pipe(header(banner.full, { package : package }))
		.pipe(gulp.dest(paths.styles.output))
		.pipe(rename({ suffix: '.min' + fileVersion }))
		.pipe(minify({
			discardComments: {
				removeAll: true
			}
		}))
		.pipe(header(banner.min, { package : package }))
		.pipe(gulp.dest(paths.styles.output));
});

// Generate SVG sprites
gulp.task('build:svgs', ['clean:dist'], function () {
	if (!settings.svgs) return;

	return gulp.src(paths.svgs.input)
		.pipe(plumber())
		.pipe(tap(function (file, t) {
			if (file.isDirectory()) {
				var name = file.relative + '.svg';
				return gulp.src(file.path + '/*.svg')
					.pipe(svgmin())
					.pipe(svgstore({
						fileName: name,
						prefix: 'icon-',
						inlineSvg: true
					}))
					.pipe(gulp.dest(paths.svgs.output));
			}
		}))
		.pipe(svgmin())
		.pipe(gulp.dest(paths.svgs.output));
});

// Copy static files into output folder
gulp.task('build:static', ['clean:dist'], function() {
	if (!settings.static) return;

	return gulp.src(paths.static.input)
		.pipe(plumber())
		.pipe(gulp.dest(paths.static.output));
});

// Lint scripts
gulp.task('lint:scripts', function () {
	if (!settings.scripts) return;

	return gulp.src(paths.scripts.input)
		.pipe(plumber())
		.pipe(jshint())
		.pipe(jshint.reporter('jshint-stylish'));
});

// Remove pre-existing content from output folders
gulp.task('clean:dist', function () {
	del.sync([
		paths.output
	]);
});

// Generate documentation
gulp.task('build:docs', ['compile', 'clean:docs'], function() {
	if (!settings.docs) return;

	return gulp.src(paths.docs.input)
		.pipe(plumber())
		.pipe(fileinclude({
			prefix: '@@',
			basepath: '@file'
		}))
		.pipe(tap(function (file, t) {
			if (/\.md|\.markdown/.test(file.path)) {
				return t.through(markdown);
			}
		}))
		.pipe(header(fs.readFileSync(paths.docs.templates + '/_header.html', 'utf8')))
		.pipe(footer(fs.readFileSync(paths.docs.templates + '/_footer.html', 'utf8')))
		.pipe(gulp.dest(paths.docs.output));
});

// Copy distribution files to docs
gulp.task('copy:dist', ['compile', 'clean:docs'], function() {
	if (!settings.docs) return;

	return gulp.src(paths.output + '/**')
		.pipe(plumber())
		.pipe(gulp.dest(paths.docs.output + '/dist'));
});

// Copy documentation assets to docs
gulp.task('copy:assets', ['clean:docs'], function() {
	if (!settings.docs) return;

	return gulp.src(paths.docs.assets)
		.pipe(plumber())
		.pipe(gulp.dest(paths.docs.output + '/assets'));
});

// Remove prexisting content from docs folder
gulp.task('clean:docs', function () {
	if (!settings.docs) return;
	return del.sync(paths.docs.output);
});

// Spin up livereload server and listen for file changes
gulp.task('listen', function () {
	livereload.listen();
	gulp.watch(paths.input).on('change', function(file) {
		gulp.start('default');
		gulp.start('refresh');
	});
});

// Run livereload after file change
gulp.task('refresh', ['compile', 'docs'], function () {
	livereload.changed();
});


/**
 * Task Runners
 */

// Compile files
gulp.task('compile', [
	'lint:scripts',
	'clean:dist',
	'build:scripts',
	'build:polyfills',
	'build:styles',
	'build:static',
	'build:svgs'
]);

// Generate documentation
gulp.task('docs', [
	'clean:docs',
	'build:docs',
	'copy:dist',
	'copy:assets'
]);

// Compile files and generate docs (default)
gulp.task('default', [
	'compile',
	'docs'
]);

// Compile files and generate docs when something changes
gulp.task('watch', [
	'listen',
	'default'
]);

package.json

{
	"name": "project-name",
	"version": "0.0.1",
	"description": "Project description...",
	"author": {
		"name": "Your Name",
		"url": "http://your-site.com"
	},
	"license": "MIT",
	"openSource": {
		"credits": "http://comma-separated-list.com, http://of-oss-projects-used.com, http://for-this-project.com"
	},
	"repository": {
		"type": "git",
		"url": "http://github.com/your-username/project"
	},
	"devDependencies": {
		"gulp": "^3.9.1",
		"node-fs": "^0.1.7",
		"del": "^2.2.2",
		"lazypipe": "^1.0.1",
		"gulp-plumber": "^1.1.0",
		"gulp-flatten": "^0.3.1",
		"gulp-tap": "^0.1.3",
		"gulp-rename": "^1.2.2",
		"gulp-header": "^1.8.8",
		"gulp-footer": "^1.0.5",
		"gulp-watch": "^4.3.11",
		"gulp-livereload": "^3.8.1",
		"jshint": "^2.9.4",
		"gulp-jshint": "^2.0.4",
		"jshint-stylish": "^2.2.1",
		"gulp-concat": "^2.6.1",
		"gulp-uglify": "^2.1.2",
		"gulp-optimize-js": "^1.1.0",
		"gulp-sass": "^3.1.0",
		"gulp-cssnano": "^2.1.2",
		"gulp-autoprefixer": "^3.1.1",
		"gulp-svgmin": "^1.2.3",
		"gulp-markdown": "^1.2.0",
		"gulp-file-include": "^0.14.0"
	}
}