build.js

'use strict';
var path = require('path');
var Promise = require('bluebird');
var asar = Promise.promisifyAll(require('asar'));
var globAsync = Promise.promisify(require('glob'));
var stylus = Promise.promisifyAll(require('stylus'));
var fs = Promise.promisifyAll(require('fs-extra'));

var readFiles = function(files) {
    return Promise.map(files, function(file) {
        return Promise.props({
            path: path.basename(file),
            content: fs.readFileAsync(file, 'utf8')
        });
    });
};

var writeFiles = function(files, outputDir) {
    return Promise.map(files, function(file) {
      var filePath = path.join(outputDir, file.path);
      return fs.outputFileAsync(filePath, file.content);
    }).all();
};

var complieStyles = function() {
    var outputDir = 'out/resources/app/frontend/static/styles';
    return globAsync('static/styles/*.styl').then(function(files) {
        return readFiles(files);
    }).then(function(files) {
        return Promise.map(files, function(file) {
            var fileName = file.path.replace(/\.styl/, '.css');
            return Promise.props({
              path: fileName,
              content: stylus.renderAsync(file.content, {
                  filename: fileName,
                  lineNumbers: true
              })
            });
        });
    }).then(function(files) {
        return writeFiles(files, outputDir);
    });
};

var copyStatic = function() {
    var from = [
        'src/frontend',
        'src/backend',
        'src/package.json',
        'src/index.html',
        'static/js',
        'static/img',
        'static/fonts',
    ];
    var to = [
        'out/resources/app/frontend',
        'out/resources/app/backend',
        'out/resources/app/package.json',
        'out/resources/app/index.html',
        'out/resources/app/frontend/static/js',
        'out/resources/app/frontend/static/img',
        'out/resources/app/frontend/static/fonts',
    ];
    return Promise.each(from, function(fromItem, index) {
        return fs.copyAsync(fromItem, to[index]);
    }).all();
};

var createAsar = function() {
    return asar.createPackageAsync('out/resources/app', 'runtime/resources/app.asar');
};

var cleanOutDirectory = function() {
    return fs.removeAsync('out');
};

var cleanAsar = function() {
    return fs.removeAsync('runtime/resources/app.asar');
};

var cleanUp = function() {
    return Promise.join(cleanOutDirectory(), cleanAsar());
};

cleanUp().then(function() {
    console.log('cleaned up');
    return complieStyles();
}).then(function() {
    console.log('styles ready');
    return copyStatic();
}).then(function() {
    console.log('static ready');
    return createAsar();
}).then(function() {
    console.log('asar ready');
});