This card is mainly an explanation how variable fonts work in CSS, not necessarily a recommendation to actually use them.

What is a variable font?

Designing and rendering fonts are two highly complex topics. For an arbitrary text to appear properly on your screen, its font must be created multiple times for different "settings" like stroke width (boldness) and style (e.g. italic).

Now as web developers, we usually ship these variants of the same font via multiple @font-faces of the same font-family:

@font-face
  font-family...

Installation

You need to install the official plugin, it is not bundled with RubyMine by default.

Example: Setup a watcher to verify rubocop integrity

First, open Settings -> Tools -> File Watchers. Then, configure rubocop to check every change to the VCS:

Note that the "program" argument must be part of your $PATH. I worked around this constraint by using b as a shim for bundle exec.

Resources

• [File watchers documen...

curl-to-ruby is a handy tool that converts your curl command to ruby code that uses the Net::HTTP library.

Example

curl -X POST -d
  "grant_type=password&email=email&password=password"
  localhost:3000/oauth/token

will output to:

require 'net/http'
require 'uri'

uri = URI.parse("http://localhost:3000/oauth/token")
request = Net::HTTP::Post.new(uri)
request.set_form_data(
  "email" => "email",
  "grant_type" => "password",
  "password" => "password",
)

req_options =...

If you're using the webdrivers gem and VCR together, depending on your configuration, VCR will yell at you regulary.
The webdrivers gem tries to update your webdrivers on your local machine. To do so, it checks the internet for newer versions, firing an HTTP-request to e.g. https://chromedriver.storage.googleapis.com

You can "fix" this in multiple ways:

1. Update your drivers on your machine with
   RAILS_ENV=test rake webdrivers:chromedriver:update

2. Ignore the driver update-URL in your ...

When logging in Rails, you can use the log_tags configuration option to add extra information to each line, like :request_id or :subdomain. However, those are only valid inside a request context and have no effect when your application is logging from inside a Sidekiq process.
This includes custom as well as any framework logs, like query logging from ActiveRecord.

Since Sidekiq Workers run inside threads of a single process, running multiple jobs in...

If you want to get the path of a file relative to another, you can use the expand_path method with either the constant __FILE__ or the method __dir__. Read this card for more information about __FILE__ and __dir__.

Example

Structure:

.
├── bin
│   ├── format_changelog
├── CHANGELOG.md

bin/format_changelog:

#!/usr/bin/env ruby

changelog_path = ? # How to get the path to ../CHANGELOG.md independent of the working dir of the caller
changelog = File.read(changelog_path)

# ... further actions...

CSS variables are very different from preprocessor variables. While preprocessors use variables to compile a static piece of CSS, CSS custom properties are a reactive (i.e. live) part of the styles. Think of them like usual CSS properties that cascade, but have:

• A special syntax: CSS variables always start with a double-dash (--color)
• No inherent meaning: Defining a CSS variable will not change any styles in itself
• A special functionality: CSS variables can be used within the values of other properties, including CSS variables...

When you use Sentry to monitor exceptions, an important feature is Sentry's error grouping mechanism. It will aggregate similar error "events" into one issue, so you can track and monitor it more easily. Grouping is especially important when you try to silence certain errors.

It is worth understanding how Sentry's grouping mechanism works.

The default grouping mechanism

The exact algorithm has changed over time, and Sentry will keep using the algorithm t...

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...

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...

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...

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...

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...

"Open-source software (OSS) is great. Anyone can use virtually any open-source code in their projects."

Well, it depends. Licenses can make things difficult, especially when you are developing closed-source software. Since some OSS licenses even require the employing application to be open-sourced as well (looking at you, GPL), you cannot use such software in a closed-source project.

To be sure on this, we have developed a project-level integration of Pivotal's excellent [license_finder](https:/...

# Basic HTML example
<video poster="preview_image.png" controls>
  <source src="or_here.webm" type="video/webm" />
  <source src="alternative_if_browser_cant_pay_first_source.mp4" type="video/mp4" />
  <track src="optional_subtitles.vtt" kind="subtitles" srclang="de" label="Deutsch" default>
</video>

# Javascript API (notable methods and properties)
video = document.querySelector('video')
video.play()
video.pause()
video.load() // Reset to the beginning and select the best available source
video.currentSrc // The selected source
video.c...

RubyMine has a HTTP Client that can be useful to test web APIs.
Just create a .http scratch file an write your request in it.
The request can then be executed with the "Run all requests in File" button above the file.

Some alternatives:

• Postman
• Curl

The format for request is like this:

Method Request-URI HTTP-Version
Header-field: Heade...

Select2 is a fantastic library for advanced dropdown boxes, but it depends on jQuery.

Alternatives

Tom Select

There is a selectize.js fork called Tom Select. It is well tested, comes with Bootstrap 3, Bootstrap 4 and Bootstrap 5 styles and is easy to use. You might miss some advanced features.

Known issues:

• Dynamic opt-groups in AJAX requests are not supported, you need to define them in advance on the select field (see <https://github.com/selectize/selectize.js/pull/1226/...

In a web application you sometimes have tasks that can not be processed during a request but need to go to the background.
There are several gems that help to you do that, like Sidekiq or Resque.

With newer Rails you can also use ActiveJob as interface for a background processing library. See here for a list of supported queueing adapters.
For ...

Select2 comes with AJAX support built in, using jQuery's AJAX methods.
...
For remote data sources only, Select2 does not create a new element until the item has been selected for the first time. This is done for performance reasons. Once an has been created, it will remain in the DOM even if the selection is later changed.

If you have a huge collection of records for your select2 input, you can populate it via AJAX in order to not pollute your HTML with lots of <option> elements.

All you have to do is to provide...

If you render markdown from user input, an attacker might be able to use this to inject javascript code into the source code of your page.
The linked github page is a collection of common markdown XSS payloads which is handy for writing tests.

Producing arbitrary links:

[Basic](javascript:alert('Basic'))
[Local Storage](javascript:alert(JSON.stringify(localStorage)))
[CaseInsensitive](JaVaScRiPt:alert('CaseInsensitive'))
[URL](javascript://www.google.com%0Aalert('URL'))
[In Quotes]('javascript:alert("InQuotes")')

Using onload...

An unresponsive service can be worse than a down one. It can tie up your entire system if not handled properly. All network requests should have a timeout.

Here’s how to add timeouts for popular Ruby gems. All have been tested. You should avoid Ruby’s Timeout module. The default is no timeout, unless otherwise specified. Enjoy!



The linked GitHub repository is a bit like our "dev" cards deck, but groomed from a single person (Josh Branchaud). It includes an extensive list of over 900 TILs on many topics that might be interesting for most of us. (e.g. Ruby, Rails, Git, Unix..)

Ruby

Here is an excerpt of all the Ruby TILs that were new to me. I encourage you to take your time to skim over the original list as well!

• Assoc For Hashes
  • `Hash#ass...

With puma you can have concurrent requests. There are two concepts on how Puma can handle two incoming requests: Workers and Threads.

Workers

Puma can have multiple workers. Each worker is a process fork from puma and therefore a very heavy instance and can have multiple threads, that handle the incoming requests.

Example: A Puma server with 2 workers and 1 thread each can handle 2 request in parallel. A third request has to wait until the thread of one of the workers is free.

Threads

Rails is thread-safe since version 4 (n...