An example for a build process using Gulp and Browserify

gulpfile.js

var pkg = require('./package.json'),
	gulp = require('gulp'),
	less = require('gulp-less'),
	path = require('path'),
	concat = require('gulp-concat'),
	closure_compiler = require('gulp-closure-compiler'),
	jshint = require('gulp-jshint'),
	autoprefixer = require('gulp-autoprefixer'),
	rev = require('gulp-rev'),
	rimraf = require('gulp-rimraf'),
	run_sequence = require('run-sequence'),
	extend = require('gulp-extend'),
	rename = require('gulp-rename'),
	source = require('vinyl-source-stream'),
	browserify = require('browserify'),
	watchify = require('watchify'),
	notify = require('gulp-notify'),
	gutil = require('gulp-util'),
	streamify = require('gulp-streamify'),
	react = require('gulp-react'),
	reactify = require('reactify'),
	babelify = require("babelify"),
	karma = require('gulp-karma'),
	csslint = require('gulp-csslint');

var JS_SRC_DIR = './js';
var LESS_SRC_DIR = './css';
var BUILD_DIR = './build';
var JS_BUILD_DIR = BUILD_DIR + '/js';
var CSS_BUILD_DIR = BUILD_DIR + '/css';
function _get_revision_filename(prefix) {
	return prefix + '-version.json';
}

function _handle_error(task, should_end) {
	return function(err) {
		gutil.log(gutil.colors.red(err));
		notify.onError(task + ' failed, check the logs..')(err);
		if (should_end) {
			this.emit('end');
		}
	};
}

gulp.task('clear_build_dir', function() {
	return gulp.src([BUILD_DIR, './build-revisions.json'], {read: false})
		.pipe(rimraf());
});

///////////////////// Styles /////////////////////

function styles(module_name, entries, is_dev) {
	var stream = gulp.src(entries)
		.pipe(less().on('error', _handle_error('Less', true)))
		.pipe(concat(module_name + '.css'))
		.pipe(autoprefixer());

	if (!is_dev) {
		stream = stream
			.pipe(rev())
			.pipe(gulp.dest(CSS_BUILD_DIR))
			.pipe(rev.manifest())
			.pipe(rename(_get_revision_filename(module_name)));
	}

	return stream.pipe(gulp.dest(CSS_BUILD_DIR));
}

function create_styles_tasks(module_name, entries) {
	gulp.task('css_'+module_name, function() {
		return styles(module_name, entries, false);
	});
	gulp.task('css_'+module_name+'_dev', function() {
		return styles(module_name, entries, true);
	});
}

create_styles_tasks('main', [LESS_SRC_DIR + '/main.less']);
create_styles_tasks('static_page', [LESS_SRC_DIR + '/static_page.less']);

gulp.task('watch_styles', function () {
	var watcher = gulp.watch(LESS_SRC_DIR + '/*.*', ['css_main_dev', 'css_static_page_dev']);
	watcher.on('change', function(event) {
		console.log('Watcher event type: ' + event.type);
	});
});

gulp.task('css_lint', function() {
	return gulp.src([LESS_SRC_DIR + '/main.less'])
		.pipe(less().on('error', _handle_error('Less', true)))
		.pipe(csslint('./.csslintrc'))
		.pipe(csslint.reporter())
		.pipe(concat('main.csslint.css'))
		.pipe(gulp.dest('./'));
});

///////////////////// Scripts /////////////////////

function scripts(module_name, entries, is_dev) {
	var bundler = browserify({
		entries: entries,
		paths: ['./node_modules', JS_SRC_DIR],
		debug: is_dev,
		cache: {}, // required for watchify
		packageCache: {}, // required for watchify
		fullPaths: is_dev // required to be true only for watchify
	});
	if (is_dev) {
		bundler = watchify(bundler);
	}

	bundler.transform(babelify);
	bundler.transform(reactify);

	var rebundle = function() {
		console.log("Rebundling " + module_name);
		var stream = bundler.bundle();
		stream.on('error', _handle_error('Browserify'));

		stream = stream.pipe(source(module_name + '.js'));

		if (!is_dev) {
			stream = stream
				.pipe(streamify(closure_compiler({
					compilerPath: './utils/compiler.jar',
					fileName: module_name + '.js',
					compilerFlags: {
						jscomp_off: ['uselessCode']
					}
				})))
				.pipe(rev())
				.pipe(gulp.dest(JS_BUILD_DIR))
				.pipe(rev.manifest())
				.pipe(rename(_get_revision_filename(module_name + '.js')));
		}

		return stream.pipe(gulp.dest(JS_BUILD_DIR));
	};

	bundler.on('update', rebundle);
	return rebundle();
}

function create_script_tasks(module_name, entries) {
	gulp.task('js_'+module_name, function() {
		return scripts(module_name, entries, false);
	});
	gulp.task('js_'+module_name+'_dev', function() {
		return scripts(module_name, entries, true);
	});
}

create_script_tasks('main', [JS_SRC_DIR + '/main.js']);

gulp.task('js_plugins', function() {
	return gulp.src(pkg.js.plugins)
		.pipe(concat('plugins.js'))
		.pipe(rev())
		.pipe(gulp.dest(JS_BUILD_DIR))
		.pipe(rev.manifest())
		.pipe(rename(_get_revision_filename('plugins')))
		.pipe(gulp.dest(JS_BUILD_DIR));
});

gulp.task('js_plugins_dev', function() {
	return gulp.src(pkg.js.plugins)
		.pipe(concat('plugins.js'))
		.pipe(gulp.dest(JS_BUILD_DIR));
});

gulp.task('js_vendor_copy', function() {
	return gulp.src(JS_SRC_DIR + '/vendor/*.js')
		.pipe(gulp.dest(JS_BUILD_DIR + '/vendor/'))
});

gulp.task('js_lint', function() {
	return gulp.src([JS_SRC_DIR + '/**/*.js'])
		.pipe(react())
		.pipe(jshint())
		.pipe(jshint.reporter('default'))
		.pipe(jshint.reporter('fail'));
});

gulp.task('js_test', function() {
	var files = [
		JS_SRC_DIR + '/polyfills/es5-shim.min.js',
		JS_SRC_DIR + '/vendor/jquery-1.11.0.min.js',
		JS_SRC_DIR + '/vendor/react-with-addons-0.13.3.js',
		JS_SRC_DIR + '/plugins/underscore-1.8.3.min.js',
		JS_SRC_DIR + '/**/__tests__/*.js'
	];
	return gulp.src(files)
		.pipe(karma({
			configFile: 'karma.conf.js',
			action: 'run'
		}));
});

////////////////////////////////////////////////////

gulp.task('combine_version_manifest', function() {
	return gulp.src(BUILD_DIR + '/**/*-version.json')
		.pipe(rimraf())
		.pipe(extend(BUILD_DIR + '/build-revisions.json'))
		.pipe(gulp.dest('.'));
});

gulp.task('test', ['js_test'])

gulp.task('default', function() {
	run_sequence('clear_build_dir', [
		'test',
		'js_lint',
		'css_main',
		'css_static_page',
		'js_main',
		'js_plugins',
		'js_vendor_copy',
	], 'combine_version_manifest');
});

gulp.task('develop', [
	'js_plugins_dev',
	'js_main_dev',
	'css_main_dev',
	'css_static_page_dev',
	'watch_styles',
]);

gulp.task('lint', ['js_lint']);