4018 cards

Rails: Default HTTP status codes when redirecting

When redirecting you should take care to use the right HTTP status code.

From controllers

When redirecting from a controller Archive , the default status code is 302 Found (aka Moved Temporarily):


Show a JS fiddle in fullscreen

If you have a JS fiddle, you can open it in fullscreen by appending /show to the URL.

Example: https://jsfiddle.net/b275g910/3 => https://jsfiddle.net/b275g910/3/show


Be very careful with 301 and 308 redirects

Browsers support different types of redirects.

Be very careful with these status codes:

  • 301 Moved Permanently
  • 308 Permanent Redirect

Most browsers seem to cache these redirects forever, unless you set different Cache-Control headers. If you don't have any cache control headers, you can never change them without forcing users to empty their cache.


By default Archive Rails sends a ...


Project management best practices: Budget control

When starting a project we always make a good estimate of all known requirements, and plan budgets and available developers accordingly.

Requirements change. Budgets usually don't.

To make sure a project stays on track, we update our estimates once a month and compare them to the remaining budget. If this doesn't match any more, we have to act.

To update an estimate, do the following:

  • Start with the most recent estimate for the project.
  • Which stories have been completed? Set their estimate to zero.
  • Have any requirements cha...
Linked contentRepeats

Choosing the right gems for your project

Adding a gem means you take over the liability towards the external code.


Based on " To gem, or not to gem Archive ":

  • Gem is really needed (prefer writing your own code for simple requirements without many edge cases)
  • Gem is tested well (coverage and quality)
  • Gem has a good code quality
  • Gem's licence fits to the project requirement
  • Try to avoid gems that do much more than your requireme...

IRB's multi-line autocomplete and how to disable it

Recent IRB versions include a multi-line autocomplete which may be helpful to novice users but can be distracting.

Cycling through options works by pressing the Tab key (as usual), and for some methods you also get some kind of documentation, though the quality of results is usually not on par with your IDE of choice.

I have found that it also slows down my IRB in some cases, or that pressing the Backspace key does not always reliably remove characters, which I find more annoying than useful.

You may disable multi-line autocomplete by

  • ...

Debug file system access in a Rails application

It might sometimes be useful to check whether your Rails application accesses the file system unnecessarily, for example if your file system access is slow because it goes over the network.

The culprit might be a library like carrierwave that checks file existence or modification times, whereas your application could determine all this from your database.

Introducing strace

One option it to use strace for this, which logs all system calls performed by a process.

To do this, start your rails server using something like


SameSite cookies

TL;DR Most web applications do not require action on this. SameSite=None (old browser default) will continue to work, and SameSite=Lax (new Chrome default, gradually rolled out Archive ) is an even better default for cookies. Set SameSite=Strict only for extra security in special cases (see below). If your application is rendered in an iframe (e.g. a video player or some news stream), you need to configure its relevant cookies as SameSite=None.

The SameSite cookie attribute targets **c...


Webpack(er): Analyze the size of your JavaScript components

We're always striving towards keeping our website's JavaScript as small as possible.

If you're using webpack(er), you can use the webpack-bundle-analyzer plugin Archive to get a good overview, which of your JavaScript modules take up how much space, and where you can optimize.

To use it, add it via npm or yarn

yarn add webpack-bundle-analyzer

Then add this to your environment.js:

// Uncomment this code to show statistics of bundle sizes. Generated file will automatically o...

makandra_sidekiq 0.2.0 respects the configured Sidekiq timeout

There was an issue with makandra_sidekiq < 0.2 concerning the stopping of Sidekiq.

Sidekiq < 6 has two finishing timeouts Archive : one for finishing things itself (A), and one for sidekiqctl before killing a running Sidekiq instance (B). While USAGE banner of sidekiqctl advises to have B always greater than A, makandra_sidekiq < 0.2 runs sidekiqctl without passing a timeout. If the Sidekiq instance is configured with a timeout higher than the default 10s timeout of sidekiqctl, `sideki...

Capybara: Most okayest helper to download and inspect files

Testing file download links in an end-to-end test can be painful, especially with Selenium.

The attached download_helpers.rb provides a download_link method for your Capybara tests. It returns a hash describing the download's response:

details = download_link('Download report')
details[:disposition]  # => 'attachment' or 'inline'
details[:filename]     # => 'report.txt'
details[:text]         # => file content as string
details[:content_type] # => 'text/plain'


Compared to [other approaches](...


PSA: Umlauts are not always what they seem to be

When you have a string containing umlauts which don't behave as expected (are not matched with a regexp, can't be found with an SQL query, do not print correctly on LaTeX documents, etc), you may be encountering umlauts which are not actually umlaut characters.

They look, depending on the font, like their "real" umlaut counterpart:

  • ä ↔ ä
  • ö ↔ ö
  • ü ↔ ü

However, they are not the same:

>> 'ä' == 'ä'
=> false
>> 'ä'.size
=> 1
>> 'ä'.size
=> 2

Looking at how those strings are constructed reveals what is going...

Linked contentRepeats

The Difference Between Width and Flex Basis | Geddski

Within a Flexbox layout, there are multiple CSS attributes that may affect a child's basis (the initial width before flexing). You might be confused how flex-basis, width, min-width and the intrinsic width of your content play together.

The attached article Archive explains the differences. In summary:

  • If a flex-basis is set, that is used as the basis
  • If no flex-basis is set, the width is used as the basis
  • If neither flex-basis nor width is set, the content...

Ruby: __FILE__, __dir__ and symlinks

Ruby's __FILE__ keyword returns the path to the current file. On popular for this are Ruby binaries:

#!/usr/bin/env ruby
$LOAD_PATH << File.expand_path('../../lib', __FILE__)
require 'my_cli'

However, if you create a symlink to this file, this will no longer work. __FILE__ will resolve to the path of the symlink, not to its target.

One solution is to use File.realpath(__FILE__).

In Ruby 2+ you can also use this:

$LOAD_PATH << File.expand_path('../lib', __dir__)

__dir__ is simply a shortcut for `Fi...


Stop animations and network polling when the document tab isn't visible

Is your application doing something expensive every few seconds? Maybe an animated slider that rotates images? Maybe you are updating data over the network every five minutes?

It's a good idea to pause this if the your document tab is not even visible to the user. This saves your user's battery and data plan.

You can ask document.visibilityState Archive whether this tab is visible:

function pulse() {
  if (!document.visibilityState || document.visibilityState =...

JavaScript: Testing the type of a value

Checking if a JavaScript value is of a given type can be very confusing:

  • There are two operators typeof and instanceof which work very differently.
  • JavaScript has some primitive types, like string literals, that are not objects (as opposed to Ruby, where every value is an object).
  • Some values are sometimes a primitive value (e.g. "foo") and sometimes an object (new String("foo")) and each form requires different checks
  • There are three different types for null (null, undefined and NaN) and each has different rules for...

How to quickly inspect an Angular scope in your webkit browser

Current webkit browsers like Chrome and Safari have a special variable in their consoles that refers to the selected DOM node in the elements panel. This lets us easily inspect Angular scopes.

  1. Right click in the page and click "Inspect" to open the Dev Tools

  2. Select the element you're interested in from the elements panel

  3. Focus the console (in Chrome, hit ESC)

  4. Get the scope object and store it

    // That is:
    element = $0 // Store element
    $element = $(element) // Wrap with j...

net-ssh and openssl-3.0.0

Ruby version 3.1 uses by default the gem openssl-3.0.0. This can cause issues with the gem net-ssh (6.1.0). This is a known bug Archive .

Typically this can cause an error while deploying an application with capistrano:

could not verify server signature (SSHKit::Runner::ExecuteError)


Ed25519::VerifyError: signature verification failed!

As temporary workaround add the following line to your Gemfile:

gem 'openssl', '<3'

For more information check [the compatibility no...

This website uses short-lived cookies to improve usability.
Accept or learn more