The nokogiri gem provides different packages for several platforms. Each platform-specific variant ships pre-built binaries of libxml2, e.g. x86_64-linux includes binaries for 64bit Linux on Intel/AMD...
...This significantly speeds up installation of the gem, as Nokogiri no longer needs to compile libxml2. However, this also means that for each security issue with libxml2, Nokogiri maintainers have...
Flash movies (.swf files) can talk with Javascript code embedded in the same HTML page. There are two ways to do this: The preferred way is to use the ExternalInterface...
...ActionScript by calling SetVariable(name, value) on the Flash movie's DOM element. This is super-legacy, but still encountered in the field. Note that communication between a Flash movie...
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...
Authorization decides what a signed-in user is allowed to do. This lesson covers modeling roles and permissions with Consul and assignable_values. Important Work on this lesson in advisor...
You can explain what authorization is, how it differs from authentication, and the shapes it usually takes: roles, ownership, per-record permissions. You can define what each role may...
...and autoload paths. They do NOT create a module for namespacing. This is intuitive, since there normally is no module Model, or module Controller. If you want to add a...
├── models ├── uploaders # No config needed ├── util # No config needed └── workers # No config needed Sometimes it's handy to group files within a directory, but not reflect that grouping within...
...throw in some locking mechanism, but then are usually done with it. Unfortunately, transactions semantics in databases are actually very complicated, and chances are, your making some incorrect assumptions.
...engine actually has four different modes for transactions: READ UNCOMMITTED READ COMMITTED REPEATABLE READ SERIALIZABLE READ UNCOMMITED gives you the least isolation between transactions (i.e. one transaction can see most...
When your application is open for public sign up and sends out transactional e-mails to a large number of users, e-mail deliverability becomes an issue. E-mail providers...
...work hard to eliminate spam and have put in place relatively tight checks what kinds of emails they will accept, and from whom. To that end we use tools like...
In SQL, NULL represents an "unknown" value. Because of this, it does not behave like a standard piece of data when used in comparison operators. If you don't account...
If you attempt to update or filter these users using a standard toggle, you might run the following queries: SELECT * FROM users WHERE name = 'Alice';
...of a Linux process, like so: $ faketime 'last Friday 4 pm' date Fr 12. Sep 16:00:00 CEST 2025 However, we cannot just modify the time of the docker...
...need to affect the command being run inside the image. So we need to smuggle faketime into the container somehow, and activate it for the process being run.
Terser is a really good minifier ("compressor") for JavaScript code. I'm often surprised by the thoughtfulness of its compressed output. Let's take this function: function fn() {
...this to the following code: console.log(a||b?"foo":c()) Note how: The if statement has been replaced by a tertiary expression. This is often less readable, but it doesn...
Git is our version control system. This lesson covers the everyday moves — committing, branching, merging, working with a remote — and the habits that make your history pleasant to review.
...in teacher mode. Learning goals You can explain where a change lives at each stage — working copy, staging area, local repository, remote — and how it moves between them.
If you are using our opscomplete.com hosting we can set all environment variables mentioned below for your deployment on request. If you're lucky DO_NOT_TRACK=1 opts...
...are collecting data only after you opt into that. ng analytics --global disable Storybook https://storybook.js.org/docs/configure/telemetry npm run storybook -- --disable-telemetry npm run storybook -- --disable-crash-reports export STORYBOOK...
I frequently find myself needing a combination of group_by, count and sort for quick statistics. Here's a method on Enumerable that combines the three: module Enumerable
group_by(&block) .transform_values(&:count) .sort_by(&:last) .to_h end end Just paste that snippet into a Rails console and use #count_by now! Usage examples...
...messages should include the ID of the issue your code belongs to. Our preferred syntax prefixes the issue title with its ID in brackets, e.g. [FOO-123] Avatars for users...
...d+):?\s*/, '[$1] ')) .filter(Boolean); if (!titles.length) { return alert('Error: No linear issues selected'); } output = titles.join('; '); } if (prompt('Commit message: Copy to clipboard?', output)) { navigator.clipboard.writeText(output) } })(); When viewing an issue...
...for DOM elements, there are some footguns you should know about. Some lists are synchronized with the DOM Some DOM APIs return live lists that automagically update their contents as...
...reflects the change automatically: document.querySelector('#two').remove() console.log(liveList) // [#one] console.log(nonLiveList) // [#one, #two] Snapshotting a live list Lists that silently change their elements can be very surprising to work...
...forget that bad resolution: git rerere forget your_file.rb Afterwards, the badly resolved file will still be in your working directory. To get it back with confict markers, say:
...do not use request.xhr? to decide that. Use respond_to. I've too often seen code like this: def show # ... if request.xhr? render json: @user.as_json else # renders default HTML...
...just plain wrong. Web browsers often fetch JSON via XHR, but they (should) also send the correct Accept HTTP header to tell the server the data they expect to receive...
...is defined incorrectly. Raise the attributes hash given to your :reject_if lambda to see if it looks like you expect. If you are nesting forms into nested forms, each...
...a new parent record together with a new child record and will need to save the parent before you can save the child. You can opt to only show the...
...an extra rendering step just for your JavaScript. An example would be: function logBoxHeight() { box.classList.add('super-big'); console.log(box.offsetHeight); // Forces the browser to re-render *now* } Verdict: Make sure you...
...always first read, then write style-relevant values. How to debug: Chrome shows warning icons in the event list in the Timeline for scripts that cause layout trashing. Performance issue...
Static error pages To add a few basic styles to the default error pages in Rails, just edit the default templates in public, e.g. public/404.html. A limitation to these default...
...templates is that they're just static files. You cannot use Haml, Rails helpers or your application layout here. If you need Rails to render your error pages, you need...
To make CSS rules dependent on the screen size, we use media queries: @media (max-width: 500px) { // rules for screen widths of 500px or smaller } Browsers will automatically enable and...
...disable the conditional rules as the screen width changes. To detect responsive breakpoints from JavaScript, you may use the global matchMedia() function. It is supported in all browsers:
Applications must be originally written in Objective-C, C, C++, or JavaScript as executed by the iPhone OS WebKit engine...
...to be done separatly for each node version on your system, though. Install yarn 1 system-wide via apt The yarn package depends on the nodejs debian package, but with...
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | gpg --dearmor | sudo tee /etc/apt/keyrings/yarn.gpg >/dev/null echo "deb [signed-by=/etc/apt/keyrings/yarn.gpg] https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list sudo apt-get update...
When a user shares your content, a snippet with title, image, link and description appears in her timeline. By default social networks will use the window title, the first image...
...the current URL and some random text snippet for this purpose. This is often not what you want. Luckily Facebook, Twitter, etc. lets you control how your content appears in...