hack-uva-app v0.1.0

Hackathon Starter

Live Demo: http://hackathonstarter-sahat.rhcloud.com

Jump to What's new in 4.3.0?

:bulb: Looking for ES5 code? Click here.

A boilerplate for Node.js web applications.

If you have attended any hackathons in the past, then you know how much time it takes to get a project started: decide on what to build, pick a programming language, pick a web framework, pick a CSS framework. A while later, you might have an initial project up on GitHub and only then can other team members start contributing. Or how about doing something as simple as Sign in with Facebook authentication? You can spend hours on it if you are not familiar with how OAuth 2.0 works.

When I started this project, my primary focus was on simplicity and ease of use. I also tried to make it as generic and reusable as possible to cover most use cases of hackathon web apps, without being too specific. In the worst case you can use this as a learning guide for your projects, if for example you are only interested in Sign in with Google authentication and nothing else.

Testimonials

“Nice! That README alone is already gold!” — Adrian Le Bas

“Awesome. Simply awesome.” — Steven Rueter

“I'm using it for a year now and many projects, it's an awesome boilerplate and the project is well maintained!” — Kevin Granger

“Small world with Sahat's project. We were using his hackathon starter for our hackathon this past weekend and got some prizes. Really handy repo!” — Interview candidate for one of the companies I used to work with.

Table of Contents

• Features
• Prerequisites
• Getting Started
• Obtaining API Keys
• Project Structure
• List of Packages
• Useful Tools and Resources
• Recommended Design Resources
• Recommended Node.js Libraries
• Recommended Client-side Libraries
• Pro Tips
• FAQ
• How It Works
• Cheatsheets
  • ES6
  • JavaScript Date
  • Mongoose Cheatsheet
• Deployment
• Docker
• Changelog
• Contributing
• License

Features

• Local Authentication using Email and Password
• OAuth 1.0a Authentication via Twitter
• OAuth 2.0 Authentication via Facebook, Google, GitHub, LinkedIn, Instagram
• Flash notifications
• MVC Project Structure
• Node.js clusters support
• Sass stylesheets (auto-compiled via middleware)
• Bootstrap 3 + Extra Themes
• Contact Form (powered by Mailgun, Sendgrid or Mandrill)
• Account Management
• Gravatar
• Profile Details
• Change Password
• Forgot Password
• Reset Password
• Link multiple OAuth strategies to one account
• Delete Account
• CSRF protection
• API Examples: Facebook, Foursquare, Last.fm, Tumblr, Twitter, Stripe, LinkedIn and more.

Prerequisites

• MongoDB
• Node.js 6.0+
• Command Line Tools
•  Mac OS X: Xcode (or OS X 10.9+: xcode-select --install)
•  Windows: Visual Studio
•  Ubuntu /  Linux Mint: sudo apt-get install build-essential
•  Fedora: sudo dnf groupinstall "Development Tools"
•  OpenSUSE: sudo zypper install --type pattern devel_basis

Note: If you are new to Node or Express, I recommend to watch Node.js and Express 101 screencast by Alex Ford that teaches Node and Express from scratch. Alternatively, here is another great tutorial for complete beginners - Getting Started With Node.js, Express, MongoDB.

Getting Started

The easiest way to get started is to clone the repository:

# Get the latest snapshot
git clone --depth=1 https://github.com/sahat/hackathon-starter.git myproject

# Change directory
cd myproject

# Install NPM dependencies
npm install

# Or, if you prefer to use `yarn` instead of `npm`
yarn install

# Then simply start your app
node app.js

Note: I highly recommend installing Nodemon. It watches for any changes in your node.js app and automatically restarts the server. Once installed, instead of node app.js use nodemon app.js. It will save you a lot of time in the long run, because you won't need to manually restart the server each time you make a small change in code. To install, run sudo npm install -g nodemon.

Yarn vs NPM

Yarn is a new JavaScript package manager built by Facebook, Google, Exponent and Tilde. Yarn is not an attempt to replace npm, it's simply an alternative CLI client for fetching modules from the npm registry but it does have some unique benefits over using npm, most noticeably speed and consistency (via a lock file which ensures that only specific versions of dependencies are installed). Hackathon Starter includes a yarn.lock file by default and as project dependencies are updated, this file will be updated to reflect those changes.

To upgrade your local dependencies using Yarn, simply run yarn upgrade. This will update all dependencies to their latest version based on the version range specified in the package.json file. The yarn.lock file will be recreated as well. For further information, please see the official documention for managing dependencies and upgrading dependencies. This Yarn vs NPM article by SitePoint also has some very useful information.

Obtaining API Keys

To use any of the included APIs or OAuth authentication methods, you will need to obtain appropriate credentials: Client ID, Client Secret, API Key, or Username & Password. You will need to go through each provider to generate new credentials.

Hackathon Starter 2.0 Update: I have included dummy keys and passwords for all API examples to get you up and running even faster. But don't forget to update them with your credentials when you are ready to deploy an app.

Note: When you ready to deploy to production don't forget to add your new url to Authorized Javascript origins and Authorized redirect URI, e.g. http://my-awesome-app.herokuapp.com and http://my-awesome-app.herokuapp.com/auth/google/callback respectively. The same goes for other providers.

Note: After a successful sign in with Facebook, a user will be redirected back to home page with appended hash #_=_ in the URL. It is not a bug. See this Stack Overflow discussion for ways to handle it.

Project Structure

Note: There is no preference how you name or structure your views. You could place all your templates in a top-level views directory without having a nested folder structure, if that makes things easier for you. Just don't forget to update extends ../layout and corresponding res.render() paths in controllers.

List of Packages

Useful Tools and Resources

• JavaScripting - The Database of JavaScript Libraries
• JS Recipes - JavaScript tutorials for backend and frontend development.
• Jade Syntax Documentation by Example - Even better than official Jade docs.
• HTML to Jade converter - Extremely valuable when you need to quickly copy and paste HTML snippets from the web.
• JavascriptOO - A directory of JavaScript libraries with examples, CDN links, statistics, and videos.
• Favicon Generator - Generate favicons for PC, Android, iOS, Windows 8.

Recommended Design Resources

• Code Guide - Standards for developing flexible, durable, and sustainable HTML and CSS.
• Bootsnipp - Code snippets for Bootstrap.
• UIBox - Curated HTML, CSS, JS, UI components.
• Bootstrap Zero - Free Bootstrap templates themes.
• Google Bootstrap - Google-styled theme for Bootstrap.
• Font Awesome Icons - It's already part of the Hackathon Starter, so use this page as a reference.
• Colors - A nicer color palette for the web.
• Creative Button Styles - awesome button styles.
• Creative Link Effects - Beautiful link effects in CSS.
• Medium Scroll Effect - Fade in/out header background image as you scroll.
• GeoPattern - SVG background pattern generator.
• Trianglify - SVG low-poly background pattern generator.

Recommended Node.js Libraries

• Nodemon - Automatically restart Node.js server on code changes.
• geoip-lite - Geolocation coordinates from IP address.
• Filesize.js - Pretty file sizes, e.g. filesize(265318); // "265.32 kB".
• Numeral.js - Library for formatting and manipulating numbers.
• Node Inspector - Node.js debugger based on Chrome Developer Tools.
• node-taglib - Library for reading the meta-data of several popular audio formats.
• sharp - Node.js module for resizing JPEG, PNG, WebP and TIFF images.

Recommended Client-side Libraries

• Framework7 - Full Featured HTML Framework For Building iOS7 Apps.
• InstantClick - Makes your pages load instantly by pre-loading them on mouse hover.
• NProgress.js - Slim progress bars like on YouTube and Medium.
• Hover - Awesome CSS3 animations on mouse hover.
• Magnific Popup - Responsive jQuery Lightbox Plugin.
• jQuery Raty - Star Rating Plugin.
• Headroom.js - Hide your header until you need it.
• X-editable - Edit form elements inline.
• Offline.js - Detect when user's internet connection goes offline.
• Alertify.js - Sweet looking alerts and browser dialogs.
• selectize.js - Styleable select elements and input tags.
• drop.js - Powerful Javascript and CSS library for creating dropdowns and other floating displays.
• scrollReveal.js - Declarative on-scroll reveal animations.

Pro Tips

• When installing an NPM package, add a --save flag, and it will be automatically added to package.json as well. For example, npm install --save moment.
• Use async.parallel() when you need to run multiple asynchronous tasks, and then render a page, but only when all tasks are completed. For example, you might want to scrape 3 different websites for some data and render the results in a template after all 3 websites have been scraped.
• Need to find a specific object inside an Array? Use _.find function from Lodash. For example, this is how you would retrieve a Twitter token from database: var token = _.find(req.user.tokens, { kind: 'twitter' });, where 1st parameter is an array, and a 2nd parameter is an object to search for.

FAQ

Why do I get 403 Error: Forbidden when submitting a form?

You need to add the following hidden input element to your form. This has been added in the pull request #40 as part of the CSRF protection.

input(type='hidden', name='_csrf', value=_csrf)

Note: It is now possible to whitelist certain URLs. In other words you can specify a list of routes that should bypass CSRF verification check.

Note 2: To whitelist dynamic URLs use regular expression tests inside the CSRF middleware to see if req.originalUrl matches your desired pattern.

I am getting MongoDB Connection Error, how do I fix it?

That's a custom error message defined in app.js to indicate that there was a problem connecting to MongoDB:

mongoose.connection.on('error', () => {
  console.error('MongoDB Connection Error. Please make sure MongoDB is running.');
});

You need to have a MongoDB server running before launching app.js. You can download MongoDB here, or install it via a package manager. Windows users, read Install MongoDB on Windows.

Tip: If you are always connected to the internet, you could just use mLab or Compose instead of downloading and installing MongoDB locally. You will only need to update database credentials in .env file.

I get an error when I deploy my app, why?

Chances are you haven't changed the Database URI in .env. If MONGODB/MONGOLAB_URI is set to localhost, it will only work on your machine as long as MongoDB is running. When you deploy to Heroku, OpenShift or some other provider, you will not have MongoDB running on localhost. You need to create an account with mLab or Compose, then create a free tier database. See Deployment for more information on how to setup an account and a new database step-by-step with mLab.

Why Pug (Jade) instead of Handlebars?

When I first started this project I didn't have any experience with Handlebars. Since then I have worked on Ember.js apps and got myself familiar with the Handlebars syntax. While it is true Handlebars is easier, because it looks like good old HTML, I have no regrets picking Jade over Handlebars. First off, it's the default template engine in Express, so someone who has built Express apps in the past already knows it. Secondly, I find extends and block to be indispensable, which as far as I know, Handlebars does not have out of the box. And lastly, subjectively speaking, Jade looks much cleaner and shorter than Handlebars, or any non-HAML style for that matter.

Why do you have all routes defined in app.js?

For the sake of simplicity. While there might be a better approach, such as passing app context to each controller as outlined in this blog, I find such style to be confusing for beginners. It took me a long time to grasp the concept of exports and module.exports, let alone having a global app reference in other files. That to me is a backward thinking. The app.js is the "heart of the app", it should be the one referencing models, routes, controllers, etc. When working solo on small projects I actually prefer to have everything inside app.js as is the case with this REST API server.

Why is there no Mozilla Persona as a sign-in option?

If you would like to use Persona authentication strategy, use the pull request #64 as a reference guide. I have explained my reasons why it could not be merged in issue #63.

How do I switch SendGrid for another email delivery service, like Mailgun or SparkPost?

Inside the nodemailer.createTransport method arguments, simply change the service from 'Sendgrid' to some other email service. Also, be sure to update both username and password below that. See the list of all supported services by Nodemailer.

How It Works (mini guides)

This section is intended for giving you a detailed explanation about how a particular functionality works. Maybe you are just curious about how it works, or maybe you are lost and confused while reading the code, I hope it provides some guidance to you.

###Custom HTML and CSS Design 101

HTML5 UP has many beautiful templates that you can download for free.

When you download the ZIP file, it will come with index.html, images, css and js folders. So, how do you integrate it with Hackathon Starter? Hackathon Starter uses Bootstrap CSS framework, but these templates do not. Trying to use both CSS files at the same time will likely result in undesired effects.

Note: Using the custom templates approach, you should understand that you cannot reuse any of the views I have created: layout, home page, api browser, login, signup, account management, contact. Those views were built using Bootstrap grid and styles. You will have to manually update the grid using a different syntax provided in the template. Having said that, you can mix and match if you want to do so: Use Bootstrap for main app interface, and a custom template for a landing page.

Let's start from the beginning. For this example I will use Escape Velocity template:

Note: For the sake of simplicity I will only consider index.html, and skip left-sidebar.html, no-sidebar.html, right-sidebar.html.

Move all JavaScript files from html5up-escape-velocity/js to public/js. Then move all CSS files from html5up-escape-velocity/css to public/css. And finally, move all images from html5up-escape-velocity/images to public/images. You could move it to the existing img folder, but that would require manually changing every img reference. Grab the contents of index.html and paste it into HTML To Jade.

Note: Do not forget to update all the CSS and JS paths accordingly.

Create a new file escape-velocity.pug and paste the Pug markup in views folder. Whenever you see the code res.render('account/login') - that means it will search for views/account/login.pug file.

Let's see how it looks. Create a new controller escapeVelocity inside controllers/home.js:

exports.escapeVelocity = (req, res) => {
  res.render('escape-velocity', {
    title: 'Landing Page'
  });
};

And then create a route in app.js. I placed it right after the index controller:

app.get('/escape-velocity', homeController.escapeVelocity);

Restart the server (if you are not using nodemon), then you should see the new template at http://localhost:3000/escape-velocity.

I will stop right here, but if you would like to use this template as more than just a single page, take a look at how these Jade templates work: layout.pug - base template, index.pug - home page, partials/header.pug - Bootstrap navbar, partials/footer.pug - sticky footer. You will have to manually break it apart into smaller pieces. Figure out which part of the template you want to keep the same on all pages - that's your new layout.pug. Then, each page that changes, be it index.pug, about.pug, contact.pug will be embedded in your new layout.pug via block content. Use existing templates as a reference.

This is a rather lengthy process, and templates you get from elsewhere, might have yet another grid system. That's why I chose Bootstrap for the Hackathon Starter. Many people are already familiar with Bootstrap, plus it's easy to get started with it if you have never used Bootstrap. You can also buy many beautifully designed Bootstrap themes at Themeforest, and use them as a drop-in replacement for Hackathon Starter. However, if you would like to go with a completely custom HTML/CSS design, this should help you to get started!

How do flash messages work in this project?

Flash messages allow you to display a message at the end of the request and access it on next request and only next request. For instance, on a failed login attempt, you would display an alert with some error message, but as soon as you refresh that page or visit a different page and come back to the login page, that error message will be gone. It is only displayed once. This project uses express-flash module for flash messages. And that module is built on top of connect-flash, which is what I used in this project initially. With express-flash you don't have to explicitly send a flash message to every view inside res.render(). All flash messages are available in your views via messages object by default, thanks to express-flash.

Flash messages have a two-step process. You use req.flash('errors', { msg: 'Error messages goes here' } to create a flash message in your controllers, and then display them in your views:

if messages.errors
  .alert.alert-danger.fade.in
    for error in messages.errors
      div= error.msg

In the first step, 'errors' is the name of a flash message, which should match the name of the property on messages object in your views. You place alert messages inside if message.errors because you don't want to show them flash messages are actually present. The reason why you pass an error like { msg: 'Error messages goes here' } instead of just a string - 'Error messages goes here', is for the sake of consistency. To clarify that, express-validator module which is used for validating and sanitizing user's input, returns all errors as an array of objects, where each object has a msg property with a message why an error has occurred. Here is a more general example of what express-validator returns when there are errors present:

[
  { param: "name", msg: "Name is required", value: "<received input>" },
  { param: "email", msg: "A valid email is required", value: "<received input>" }
]

To keep consistent with that style, you should pass all flash messages as { msg: 'My flash message' } instead of a string. Otherwise you will just see an alert box without an error message. That is because, in partials/flash.pug template it will try to output error.msg (i.e. "My flash message".msg), in other words it will try to call a msg method on a String object, which will return undefined. Everything I just mentioned about errors, also applies to "info" and "success" flash messages, and you could even create a new one yourself, such as:

Data Usage Controller (Example)

req.flash('warning', { msg: 'You have exceeded 90% of your data usage' });

User Account Page (Example)

if messages.warning
  .alert.alert-warning.fade.in
    for warning in messages.warning
      div= warning.msg

partials/flash.pug is a partial template that contains how flash messages are formatted. Previously, flash messages were scattered throughout each view that used flash messages (contact, login, signup, profile), but now, thankfully it is uses a DRY approach.

The flash messages partial template is included in the layout.pug, along with footer and navigation.

body
    include partials/header

    .container
      include partials/flash
      block content

    include partials/footer

If you have any further questions about flash messages, please feel free to open an issue and I will update this mini-guide accordingly, or send a pull request if you would like to include something that I missed.

How do I create a new page?

A more correct way to be to say "How do I create a new route". The main file app.js contains all the routes. Each route has a callback function associated with it. Sometimes you will see 3 or more arguments to routes. In cases like that, the first argument is still a URL string, while middle arguments are what's called middleware. Think of middleware as a door. If this door prevents you from continuing forward, you won't get to your callback function. One such example is a route that requires authentication.

app.get('/account', passportConfig.isAuthenticated, userController.getAccount);

It always goes from left to right. A user visits /account page. Then isAuthenticated middleware checks if you are authenticated:

exports.isAuthenticated = (req, res, next) => {
  if (req.isAuthenticated()) {
    return next();
  }
  res.redirect('/login');
};

If you are authenticated, you let this visitor pass through your "door" by calling return next();. It then proceeds to the next middleware until it reaches the last argument, which is a callback function that typically renders a template on GET requests or redirects on POST requests. In this case, if you are authenticated, you will be redirected to Account Management page, otherwise you will be redirected to Login page.

exports.getAccount = (req, res) => {
  res.render('account/profile', {
    title: 'Account Management'
  });
};

Express.js has app.get, app.post, app.put, app.delete, but for the most part you will only use the first two HTTP verbs, unless you are building a RESTful API. If you just want to display a page, then use GET, if you are submitting a form, sending a file then use POST.

Here is a typical workflow for adding new routes to your application. Let's say we are building a page that lists all books from database.

Step 1. Start by defining a route.

app.get('/books', bookController.getBooks);

Note: As of Express 4.x you can define you routes like so:

app.route('/books')
  .get(bookController.getBooks)
  .post(bookController.createBooks)
  .put(bookController.updateBooks)
  .delete(bookController.deleteBooks)

And here is how a route would look if it required an authentication and an authorization middleware:

app.route('/api/twitter')
  .all(passportConfig.isAuthenticated)
  .all(passportConfig.isAuthorized)
  .get(apiController.getTwitter)
  .post(apiController.postTwitter)

Use whichever style that makes sense to you. Either one is acceptable. I really think that chaining HTTP verbs on app.route is very clean and elegant approach, but on the other hand I can no longer see all my routes at a glance when you have one route per line.

Step 2. Create a new schema and a model Book.js inside the models directory.

const mongoose = require('mongoose');

const bookSchema = new mongoose.Schema({
  name: String
});

const Book = mongoose.model('Book', bookSchema);
module.exports = Book;

Step 3. Create a new controller file called book.js inside the controllers directory.

/**
 * GET /books
 * List all books.
 */
const Book = require('../models/Book.js');

exports.getBooks = (req, res) => {
  Book.find((err, docs) => {
    res.render('books', { books: docs });
  });
};

Step 4. Import that controller in app.js.

const bookController = require('./controllers/book');

Step 5. Create books.pug template.

extends layout

block content
  .page-header
    h3 All Books

  ul
    for book in books
      li= book.name

That's it! I will say that you could have combined Step 1, 2, 3 as following:

app.get('/books',(req, res) => {
  Book.find((err, docs) => {
    res.render('books', { books: docs });
  });
});

Sure, it's simpler, but as soon as you pass 1000 lines of code in app.js it becomes a little difficult to navigate the file. I mean, the whole point of this boilerplate project was to separate concerns, so you could work with your teammates without running into MERGE CONFLICTS. Imagine you have 4 developers working on a single app.js, I promise you it won't be fun resolving merge conflicts all the time. If you are the only developer then it's fine. But as I said, once it gets up to a certain LoC size, it becomes difficult to maintain everything in a single file.

That's all there is to it. Express.js is super simple to use. Most of the time you will be dealing with other APIs to do the real work: Mongoose for querying database, socket.io for sending and receiving messages over websockets, sending emails via Nodemailer, form validation using express-validator library, parsing websites using Cheerio, and etc.

How do I use Socket.io with Hackathon Starter?

Dan Stroot submitted an excellent pull request that adds a real-time dashboard with socket.io. And as much as I'd like to add it to the project, I think it violates one of the main principles of the Hackathon Starter:

When I started this project, my primary focus was on simplicity and ease of use. I also tried to make it as generic and reusable as possible to cover most use cases of hackathon web apps, without being too specific.

When I need to use socket.io, I really need it, but most of the time - I don't. But more importantly, websockets support is still experimental on most hosting providers. As of October 2013, Heroku supports websockets, but not until you opt-in by running this command:

heroku labs:enable websockets -a myapp

And what if you are deploying to OpenShift? They do support websockets, but it is currently in a preview state. So, for OpenShift you would need to change the socket.io connect URI to the following:

const socket = io.connect('http://yoursite-namespace.rhcloud.com:8000');

Wait, why is it on port 8000? Who knows, and if I didn't run across this blog post I wouldn't even know I had to use port 8000.

I am really glad that Heroku and OpenShift at least have a websockets support, because many other PaaS providers still do not support it. Due to the aforementioned issues with websockets, I cannot include socket.io as part of the Hackathon Starter. For now... If you need to use socket.io in your app, please continue reading.

First you need to install socket.io:

npm install socket.io --save

Or, again, if you use Yarn:

yarn add socket.io

Replace const app = express(); with the following code:

const app = express();
const server = require('http').Server(app);
const io = require('socket.io')(server);

I like to have the following code organization in app.js (from top to bottom): module dependencies, import controllers, import configs, connect to database, express configuration, routes, start the server, socket.io stuff. That way I always know where to look for things.

Add the following code at the end of app.js:

io.on('connection', (socket) => {
  socket.emit('greet', { hello: 'Hey there browser!' });
  socket.on('respond', (data) => {
    console.log(data);
  });
  socket.on('disconnect', () => {
    console.log('Socket disconnected');
  });
});

One last thing left to change:

app.listen(app.get('port'), () => {

to

server.listen(app.get('port'), () => {

At this point we are done with the back-end.

You now have a choice - to include your JavaScript code in Pug templates or have all your client-side JavaScript in a separate file - in main.js. I will admit, when I first started out with Node.js and JavaScript in general, I placed all JavaScript code inside templates because I have access to template variables passed in from Express right then and there. It's the easiest thing you can do, but also the least efficient and harder to maintain. Since then I almost never include inline JavaScript inside templates anymore.

But it's also understandable if you want take the easier road. Most of the time you don't even care about performance during hackathons, you just want to "get shit done" before the time runs out. Well, either way, use whichever approach makes more sense to you. At the end of the day, it's what you build that matters, not how you build it.

If you want to stick all your JavaScript inside templates, then in layout.pug - your main template file, add this to head block.

script(src='/socket.io/socket.io.js')
script.
    let socket = io.connect(window.location.href);
    socket.on('greet', function (data) {
      console.log(data);
      socket.emit('respond', { message: 'Hey there, server!' });
    });

Note: Notice the path of the socket.io.js, you don't actually have to have socket.io.js file anywhere in your project; it will be generated automatically at runtime.

If you want to have JavaScript code separate from templates, move that inline script code into main.js, inside the $(document).ready() function:

$(document).ready(function() {

  // Place JavaScript code here...
  let socket = io.connect(window.location.href);
  socket.on('greet', function (data) {
    console.log(data);
    socket.emit('respond', { message: 'Hello to you too, Mr.Server!' });
  });

});

And we are done!

Cheatsheets

ES6 Cheatsheet

Declarations

Declares a read-only named constant.

const name = 'yourName';

Declares a block scope local variable.

let index = 0;

Template Strings

Using the `${}` syntax, strings can embed expressions.

const name = 'Oggy';
const age = 3;

console.log(`My cat is named ${name} and is ${age} years old.`);

Modules

To import functions, objects or primitives exported from an external module. These are the most common types of importing.

import name from 'module-name';

import * as name from 'module-name';

import { foo, bar } from 'module-name';

To export functions, objects or primitives from a given file or module.

export { myFunction };

export const name = 'yourName';

export default myFunctionOrClass

Spread Operator

The spread operator allows an expression to be expanded in places where multiple arguments (for function calls) or multiple elements (for array literals) are expected.

myFunction(...iterableObject);

<ChildComponent {...this.props} />

Promises

A Promise is used in asynchronous computations to represent an operation that hasn't completed yet, but is expected in the future.

var p = new Promise(function(resolve, reject) { });

The catch() method returns a Promise and deals with rejected cases only.

p.catch(function(reason) { /* handle rejection */ });

The then() method returns a Promise. It takes 2 arguments: callback for the success & failure cases.

p.then(function(value) { /* handle fulfillment */, function(reason) { /* handle rejection */ });

The Promise.all(iterable) method returns a promise that resolves when all of the promises in the iterable argument have resolved, or rejects with the reason of the first passed promise that rejects.

Promise.all([p1, p2, p3]).then(function(values) { console.log(values) });

Arrow Functions

Arrow function expression. Shorter syntax & lexically binds the this value. Arrow functions are anonymous.

singleParam => { statements }

() => { statements }

(param1, param2) => expression

const arr = [1, 2, 3, 4, 5];
const squares = arr.map(x => x * x);

Classes

The class declaration creates a new class using prototype-based inheritance.

class Person {
  constructor(name, age, gender) {
    this.name   = name;
    this.age    = age;
    this.gender = gender;
  }

  incrementAge() {
    this.age++;
  }
}

:gift: Credits: DuckDuckGo and @DrkSephy.

:top: back to top

JavaScript Date Cheatsheet

Unix Timestamp (seconds)

Math.floor(Date.now() / 1000);

Add 30 minutes to a Date object

var now = new Date();
now.setMinutes(now.getMinutes() + 30);

Date Formatting

// DD-MM-YYYY
var now = new Date();

var DD = now.getDate();
var MM = now.getMonth() + 1;
var YYYY = now.getFullYear();

if (DD < 10) {
  DD = '0' + DD;
} 

if (MM < 10) {
  MM = '0' + MM;
}

console.log(MM + '-' + DD + '-' + YYYY); // 03-30-2016

// hh:mm (12 hour time with am/pm)
var now = new Date();
var hours = now.getHours();
var minutes = now.getMinutes();
var amPm = hours >= 12 ? 'pm' : 'am';

hours = hours % 12;
hours = hours ? hours : 12;
minutes = minutes < 10 ? '0' + minutes : minutes;

console.log(hours + ':' + minutes + ' ' + amPm); // 1:43 am

Next week Date object

var today = new Date();
var nextWeek = new Date(today.getTime() + 7 * 24 * 60 * 60 * 1000);

Yesterday Date object

var today = new Date();
var yesterday = date.setDate(date.getDate() - 1);

:top: back to top

###Mongoose Cheatsheet

Find all users:

User.find((err, users) => {
  console.log(users);
});

Find a user by email:

let userEmail = 'example@gmail.com';
User.findOne({ email: userEmail }, (err, user) => {
  console.log(user);
});

Find 5 most recent user accounts:

User
  .find()
  .sort({ _id: -1 })
  .limit(5)
  .exec((err, users) => {
    console.log(users);
  });

Get total count of a field from all documents:

Let's suppose that each user has a votes field and you would like to count the total number of votes in your database across all users. One very inefficient way would be to loop through each document and manually accumulate the count. Or you could use MongoDB Aggregation Framework instead:

User.aggregate({ $group: { _id: null, total: { $sum: '$votes' } } }, (err, votesCount)  => {
  console.log(votesCount.total);
});

:top: back to top

Docker

You will need docker and docker-compose installed to build the application.

• Docker installation

• Common problems setting up docker

After installing docker, start the application with the following commands :

# To build the project for the first time or when you add dependencies
docker-compose build web  

# To start the application (or to restart after making changes to the source code)
docker-compose up web

To view the app, find your docker ip address + port 3000 ( this will typically be http://192.168.99.100:3000/ ).

Deployment

Once you are ready to deploy your app, you will need to create an account with a cloud platform to host it. These are not the only choices, but they are my top picks. From my experience, Heroku is the easiest to get started with, it will automatically restart your Node.js process when it crashes, zero-downtime deployments and custom domain support on free accounts. Additionally, you can create an account with mLab and then pick one of the 4 providers below. Again, there are plenty of other choices and you are not limited to just the ones listed below.

1-Step Deployment with Heroku

Note: To install Heroku add-ons your account must be verified.

Note: As an alternative to mLab, there is also Compose.

Add these two lines to app.js, just place them anywhere before app.listen():

var IP_ADDRESS = process.env.OPENSHIFT_NODEJS_IP || '127.0.0.1';
var PORT = process.env.OPENSHIFT_NODEJS_PORT || 8080;

Then change app.listen() to:

app.listen(PORT, IP_ADDRESS,() => {
  console.log(`Express server listening on port ${PORT} in ${app.settings.env} mode`);
});

Add this to package.json, after name and version. This is necessary because, by default, OpenShift looks for server.js file. And by specifying supervisor app.js it will automatically restart the server when node.js process crashes.

"main": "app.js",
"scripts": {
  "start": "supervisor app.js"
},

• Finally, you can now push your code to OpenShift by running git push -f openshift master
• Note: The first time you run this command, you have to pass -f (force) flag because OpenShift creates a dummy server with the welcome page when you create a new Node.js app. Passing -f flag will override everything with your Hackathon Starter project repository. Do not run git pull as it will create unnecessary merge conflicts.
• And you are done!

• Login to Windows Azure Management Portal
• Click the + NEW button on the bottom left of the portal
• Click COMPUTE, then WEB APP, then QUICK CREATE
• Enter a name for URL and select the datacenter REGION for your web site
• Click on CREATE WEB APP button
• Once the web site status changes to Running, click on the name of the web site to access the Dashboard
• At the bottom right of the Quickstart page, select Set up a deployment from source control
• Select Local Git repository from the list, and then click the arrow
• To enable Git publishing, Azure will ask you to create a user name and password
• Once the Git repository is ready, you will be presented with a GIT URL
• Inside your Hackathon Starter directory, run git remote add azure [Azure Git URL]
• To push your changes simply run git push azure master
• Note: You will be prompted for the password you created earlier
• On Deployments tab of your Windows Azure Web App, you will see the deployment history

• Go to Codename: Bluemix to signup for the free trial, or login with your IBM id
• Install Cloud Foundry CLI
• Navigate to your hackathon-starter directory and then run cf push [your-app-name] -m 512m command to deploy the application
• Note: You must specify a unique application name in place of [your-app-name]
• Run cf create-service mongodb 100 [your-service-name] to create a MongoDB service
• Run cf bind-service [your-app-name] [your-service-name] to associate your application with a service created above
• Run cf files [your-app-name] logs/env.log to see the *environment variables created for MongoDB.
• Copy the MongoDB URI that should look something like the following: mongodb://68638358-a3c6-42a1-bae9-645b607d55e8:46fb97e6-5ce7-4146-9a5d-d623c64ff1fe@192.155.243.23:10123/db
• Then set it as an environment variable for your application by running cf set-env [your-app-name] MONGODB_URI [your-mongodb-uri]
• Run cf restart [your-app-name] for the changes to take effect.
• Visit your starter app at http://[your-app-name].ng.bluemix.net
• Done!

Note: Alternative directions, including how to setup the project with a DevOps pipeline are available at http://ibm.biz/hackstart. A longer version of these instructions with screenshots is available at http://ibm.biz/hackstart2. Also, be sure to check out the Jump-start your hackathon efforts with DevOps Services and Bluemix video.

Google Cloud Platform

• Download and install Node.js
• Select or create a Google Cloud Platform Console project
• Enable billing for your project (there's a $300 free trial)
• Install and initialize the Google Cloud SDK

• Create an app.yaml file at the root of your hackathon-starter folder with the following contents:

  runtime: nodejs
  vm: true
  manual_scaling:
    insta