Learn how to create offline applications with service workers.

1. The amazing power of service workers
2. Writing your first service worker with vanilla JS
3. Saving recently viewed pages offline with service workers and vanilla JS
4. Offline first with service workers and vanilla JS
5. Improving web font performance with service workers
6. How to set an expiration date for items in a service worker cache
7. How to update a service worker
8. How to trigger a service worker function from the front end with vanilla JS
9. How to immediately ...

After a recent Ubuntu update I didn't see the main menu bar of the RubyMine IDE (File | Edit | View | ...) anymore.

This could be solved by changing a RubyMine registry entry:

• Search "registry" within the "Actions" search
  • press ctrl + alt + n > click on Actions > type registry > click on Registry...
• Scroll down to linux.native.menu and disable the checkbox

After rebooting RubyMine, you'll have gotten the menu bar back.

If you are trying to integrate VCR and Cucumber 4 and you're using the use_scenario_name: true option you will run into an error like this:

undefined method `feature' for #<Cucumber::RunningTestCase::TestCase:0x00005650550ba080>

Currently the VCR integration and Cucumber 4 is broken, but you can find an open issue with details and a monkey patch here.

Sometimes new versions of software introduce new bugs. In this case you might not want the package to upgrade on a simple apt upgrade run. To do so, you can set the package on hold.

Hold a package:

sudo apt-mark hold <package-name>

Remove the hold:

sudo apt-mark unhold <package-name>

Show all packages on hold:

sudo apt-mark showhold

When you set a package on hold and you run apt upgrade you will see the following output which will remind you of the hold:

...
The following packages have been kept back:
...

To disable the mostly useless automatic suggestion popups in RubyMine, go to File / Settings, then to Editor / General / Code Completion and uncheck Auto-display code completion.

You can still open the popup by pressing CTRL + Space. And you probably want to use Context-dependent word expansion instead, anyway.

In Ruby on Rails, all the routes of a given application can be found within the config/routes.rb file.
You add more and more routes in this file as your project grows.

The problem here is that this file potentially becomes very complicated to manage over the time.
That’s why it’s important to find a way to order and maintain your routes.

See: Clean your Rails routes: grouping

Sometimes the routes.rb grows very fast and each line adds mo...

In interactive commands, Git allows the user to provide one-letter input with a single key without hitting enter (docs).

# Enabled this feature globally
git config --global interactive.singlekey true

# Or enable this feature locally for a single repository
git config interactive.singlekey true

This allows you to hit "y" instead of "y + ENTER" to move to the next hunk.

Stage this hunk [y,n,q,a,d,s,e,?]?

When writing some logs to a file, that don't use Ruby's logger utility, it is often useful to sync them. So other process can read the output just in time.

Example with enabled sync

log_path = '/tmp/some_log.log'

log_file = File.open(log_path, 'a+')
log_file.sync = true

log_file.puts('Some log message')
File.read(log_path) #=> "Some log message\n"

log_file.puts('Some other message')
File.read(log_path) #=> "Some log message\nSome other message\n"

Example ...

You can do this per environment, e.g. in config/webpack/test.js:

const environment = require('./environment')
const config = environment.toWebpackConfig()
config.devtool = 'none'
module.exports = config

Here is an example with the --tags option. You need to wrap them inside --cucumber-options option of parallel_cucumber.

DISPLAY=:17 bundle exec parallel_cucumber --cucumber-options '--tags @solo' features

See more details in the docs.

Rails middlewares are small code pieces that wrap requests to the application. The first middleware gets passed the request, invokes the next, and so on. Finally, the application is invoked, builds a response and passes it back to the last middleware. Each middleware now returns the response until the request is answered. Think of it like Russian Dolls, where each middleware is a doll and the application is the innermost item.

You can run rake middleware to get the ordered list of used middlewares in a Rails application:

$> rake midd...

If you have a Ruby Pathname, you can use the method :/ to append filepaths to it.

With this method, Ruby code can look like this:

Rails.root/"features"/"fixtures"/"picture.jpg"

Alternatively you can use the #join method, which feels less magic:

Rails.root.join('features', 'fixtures', 'picture.jpg')

We structure our CSS using the BEM pattern.

Our naming convention for blocks, elements and modifiers has evolved over the years. This card shows our current style and various alternative styles that you might encounter in older projects.

The difference between the various styles are mostly a matter of taste and optics. I do recommend to not mix styles and be consistent within a given project.

Current convention

Our current BEM naming convention looks...

I experienced a lot of issues with google chrome that made it almost impossible to work with it. Here are some of them:

• minimized windows stay hidden
• maximized windows overlap system bars (like the status bar of Ubuntu Mate on the top edge of the screen)
• windows cannot be resized

I finally discovered a setting that fixed these issues for me:

• go to chrome://settings/appearance
• activate Use system title bar and borders

I'm not sure if this setting was changed by me or if it was the browser default.

Grundidee

CSP hat zum Ziel einen Browser-seitigen Mechanismus zu schaffen um einige Angriffe auf Webseiten zu verhindern, hauptsächlich XSS-Angriffe.

Einschub: Was ist XSS?

XSS = Cross Site Scripting. Passiert wenn ein User ungefiltertes HTML in die Webseite einfügen kann.

<div class="comment">
  Danke für den interessanten Beitrag! <script>alert('you have been hacked')</script>
</div>

Rails löst das Problem weitgehend, aber

• Programmierfehler weiter möglich
• manchmal Sicherheitslücken in Gems oder Rails

Lösungsid...

Ruby's File class has a handy method binary? which checks whether a file is a binary file. This method might be telling the truth most of the time. But sometimes it doesn't, and that's what causes pain. The method is defined as follows:

# Returns whether or not +file+ is a binary file.  Note that this is
# not guaranteed to be 100% accurate.  It performs a "best guess" based
# on a simple test of the first +File.blksize+ characters.
#
# Example:
#
#   File.binary?('somefile.exe') # => true
#   File.binary?('somefile.txt') # => fal...

This note is a reminder that there is something called AppArmor that could cause weird errors ("File not found", "Can't open file or directory", ...) after configuration changes, e.g. when changing MySQL's data directory.

Remember to have a look at AppArmor's daemon configuration (usually at /etc/apparmor.d/) if you change daemon configuration and run into errors such as the one above.

grep is the go-to CLI tool to accomplish tasks like filtering large files for arbitrary keywords. When additional context is needed for search results, you might find yourself adding flags like -B5 -A10 to your query. Now, every search result covers 16 lines of your bash.

There is another way: You can easily pipe your search results to the VIM editor and cycle through them.

Example: Searching for local occurrences of "User"

vim -q <(grep -Hn -r "User" .)

# vim -q starts vim in the "quickfix" mode. See ":help quickfix"
# grep...

If you migrate a Rails application from Sprockets to Webpack(er), you can either transpile your CoffeeScript files to JavaScript or integrate a CoffeeScript compiler to your new process. This checklist can be used to achieve the latter.

1. If you need to continue exposing your CoffeeScript classes to the global namespace, define them on window directly:

-class @User
+class window.User

2. Replace Sprocket's require statement with Webpacker's...

We're pleased to announce Ruby 3’s new language for type signatures, RBS. One of the long-stated goals for Ruby 3 has been to add type checking tooling. After much discussion with Matz and the Ruby committer team, we decided to take the incremental step of adding a foundational type signature language called “RBS,” which will ship with Ruby 3 along with signatures for the stdlib. RBS command line tooling will also ship with Ruby 3, so you can generate signatures for your own Ruby code.

Ruby 3 is coming, and it will have optional type sign...

4.0.0 2020-07-30

Compatible changes

• Improved documentation; README now includes command options.
• Improvement #90: geordi console, geordi deploy, geordi rake and geordi shell now work correctly if the project hasn't been bundled before
• Use binstubs if present – breaks Geordi execution when a binstub is not working

Breaking changes

• Removed deprecated executables

GoodJob is a new background worker gem. It's compatible with ActiveJob.

We're huge fans of Sidekiq for its stability and features. One advantage of GoodJob over Sidekiq is that GoodJob doesn't require Redis. So in cases where you don't have Redis or don't want to pay for a Redis HA quorum node, this might be an alternative worth checking out.

These warnings are printed when the etc Gem is installed, while etc is also included in Ruby. Fix with:

gem uninstall etc

Most forms have a single submit button that will save the record when pressed.

Sometimes a form needs additional submit buttons like "accept" or "reject". Such buttons usually attempt a state transition while updating the record.

To process a form with multiple buttons, your server-side code will need to know which button was pressed. To do so you can give each submit button a different [formaction] attribute. This will override the ...