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Ask HN: Can you suggest some good JavaScript projects to read and learn?
109 points by balajics on July 24, 2015 | hide | past | web | favorite | 46 comments

This is what I came to suggest as well. I would also say that Express is a good one as well if you're looking to learn Node. Not quite as clear as the annotated source for Backbone, but well commented.

I also liked the "Let's Make a Framework" posts at DailyJS. DailyJS in general was a great blog that is now closed, but the archives are still up.



+1 for Backbone. It is very well documented

I was about to suggest lodash.

I'm also interested to see a mid-size scale SPA project that has excellent unit-testing and integration-testing.

I've read a lot about how JS can make programmer productive, I've also read a lot how code can be succinct and all that jazz because of JS, but I have _never seen_ a well-architected, well-documented, well-automated-tested non-todomvc SPA codebase.

This isn't a sarcasm or criticism but a serious and legitimate "ASK" because I'm working on a large-scale SPA project that's hard to write automation test other than Selenium.

I'm looking for something that can taught me:

1. Unit-testing (with some level of mocking)

2. Integration-testing (testing various components without hitting the UI but all the way up to the sending request, kind of like driving the front-end code without the UI).

3. Best practices/patterns for architecting large-scale SPA (hint: generic EventBus tend to be abused).

We have a mid-size scale SPA and its suffering because of bloat. Functions are 2-500 lines long as an example. we've had critical bugs in the last 2 weeks and I got fed up and decided to start learning unit testing. Its been absolutely painful to get everything setup and started (Visual Studio). Nothing works. I would love to see a well written project to base my tests off of.

I would really love to see a well written SPA with testing, but I fear its almost reaching unicorn status. Most projects suffer from deadlines so they'll just never be written the way they should be and instead, the flow is now: patch it and move on.

That's not quite correct.

I've had good success in architecting/designing classical web-app (MVC-ish as overall architecture and minimum JS on front-end).

I can write unit-test with mocking and integration-test with in-memory database as part of my build/compile loop.

But I struggled a lot with front-end.

Ah yeah, we're having lots of issues with front end bugs causing crashes.

Front-end bugs causing crashes of... the back-end? That's a back-end bug.

I tried doing unit testing on our SPA codebase (200 k lines JS) for a while, but found it to not be worth the effort. UI is better tested through integration tests. We use selenium instead of jasmine these days. We have a ton of unit tests in the server code though, because it makes more sense there.

I think the right approach is to build from the ground up for testability both on unit-test and integration-test.

But one has to be very careful how to structure the pieces/components.

For example:

Do not write extensive unit-test on the UI but definitely have extensive Selenium tests for the UI _library_ (if you are a library builder). If you are a library user, assume the UI works as advertised and attaching/removing event-listener can be considered "configuration" type of code: test it once to see if it is configured properly and that's it!

If the SPA uses some sort of MVC/MVP, I'm hoping I can:

1. For unit-test

- unit-test individual M,V,C,P, Service, Helper, Model Validators, etc

- ability to mock different aspects

2. For integration-test

- ability to construct the whole thing (MVC/P) including the back-end, mock the View, and start controlling/simulating the code execution from the Controller/Presenter

The integration test can cover more than the unit-test to the point almost close to Selenium type of test but not as brittle as Selenium.

This game is a tool for experimentation - it gave me motivation to start learning. You need to write the control software for an elevator (or elevators), which has levels of increasing difficulty to clear, which will mean re-evaluating and rewriting your code to perform better under different scenarios.


Holy cow... honestly, I'm not even that interested in getting better at JS, but this game looks like so much fun. If I ever find a game like this for traffic-light simulation, that's the last day I leave the house.

Reflux and it's associated tools for some concise, well written ES6/7 patterns (https://github.com/gaearon/redux)

Gaearon is actually a hell of a JS developer (https://github.com/gaearon).

Not a readable resource, but I feel it is worth the exception - Watch Dan Abramov's talk [1] about Redux (Reducers + Flux). Gives great insight into his motivation for creating React Hot Loader and Redux.

+1 for Dan (aka Gaearon) being an excellent developer

[1] https://www.youtube.com/watch?v=xsSnOQynTHs

You mentioned Reflux but linked to Redux.

Ah, apologies, meant Redux. So many flux frameworks and their names are all similar.

Read the backbone source. http://backbonejs.org/docs/backbone.html

Read the underscore Source first: http://underscorejs.org/docs/underscore.html

The same todo app implemented in a bunch of frameworks:


It's not a project, but Airbnb have updated their Javascript style guide to ES6. It's a good read on how to write and structure javascript.


If you're willing to learn about patterns, jQuery and Underscore.js are excellent places to look at.

If you're looking for something harder and unconventional, see React source. It also has some low hanging fruit for pull requests.

If documentation and comments are important for you to learn, Backbone.js is way ahead of everyone else in those terms.

I would also look at smaller indie projects. The source is smaller, forking and adding something is easier. Pull requests are easier too.

I asked this before and I hope it helps https://news.ycombinator.com/item?id=8128400

ExpressJS is pretty interesting with its nested routers, middleware, request handling function as the app, and adjusting the prototype on each request.

It gets kind of hairy so I did a blog post on it: http://www.nickstefan.net/blog/view/express-under-the-hood

Its funny everybody is talking about Backbone. With all the new frameworks out there, Backbone seems to be forgotten. And yet, it's persevered and continues to improve itself seemingly now under the radar.

It's such a straight forward library to use and build stuff with - plus the code is very well annotated for anybody just starting out.

One of the best starting points for building a SPA that I've seen is the Angular Fullstack generator https://github.com/DaftMonk/generator-angular-fullstack

This generator uses Angular best practices, has Jasmine and Karma built in for solid unit and integration (called e2e tests in Angular) testing. The built-in generators even build pages, controllers, and add the unit test files along with the new routes. In addition, authentication via Passport.js is in the box. In my opinion it's an easy to extend, robust solution for building a non-trivial SPA. Even has hooks for easy deployment to Heroku.

That being said, I have been trying to learn React lately and have yet to find a similar thing for a React-based stack.

Can you briefly expand the e2e test aspect of Angular?

I'm looking to learn ways to do e2e test without touching the DOM (e.g.: from Controller all the way up to the back-end; imagine firing up Chrome DevTools console and start writing JS code that executes some logic and eventually fires AJAX request and process the response, of course in this case the View will be mocked but the app logic and everything else can be executed).

Checkout Angular's guide on e2e testing using https://docs.angularjs.org/guide/e2e-testing

Also read about Protractor, http://angular.github.io/protractor/#/, their e2e testing framework. These tests generally should be run in the browser. You can run them in PhantomJS, a command line browser simulator, but it's not the same and there are sometimes issues that don't get caught by Phantom. Best to run those tests in an actual browser.

I went over those pages briefly and I wish it's not Selenium-like but it kinda is... :(

The original jquery source w/ annotations: http://genius.it/5088474/ejohn.org/files/jquery-original.htm...

BackboneJS is a really well-written library, even if it's now beginning to lose popularity. The source code is small enough that it should be easy to read and understand within a few weeks.

No mention of polymer yet. Web components are a good candidate for the future structure of the web. Just mind the recent bump to 1.0 and with a slew of components still developed for 0.5

I wanted to make HTML5 games. So I searched and eventually came across an open-source "Catch the demon" game[1]. I studied it and some other Javascript code, and modified the game to take mouse input instead of keyboard[2]. You might be able to make better modifications, or even a better game!



I could, but JavaScript has such a broad application these days that you should be more specific as to what you're goals are

If you want something more NodeJS oriented you can start exploring Ghost source code [1]. It has amazing Promise-based + express infrastructure, in which you can find a lot of patterns to help you build your next project.

1 : https://github.com/TryGhost/Ghost

No Frameworks used, just "modern" JavaScript: https://github.com/mozilla-b2g/gaia Have learned some things by reading the code.

This is an impossible question to answer correctly.

https://github.com/hybridgroup/cylon-sphero because you can use it to control robots?

The New York Times website has some great annotated JS source code.

Lodash has some of the best javascript code out there.


Emberjs is very well documented too and is choke full of some very good design patterns and concepts.

YMMV as its a huge codebase and it might be hard to figure out where to start.

Take a look at the d3.js source code

This is not good advice.

The Khan Academy open sources their site's code.

AngularJs is the best

React.JS is the best

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