The way that Javascript schedules timeouts and promise callbacks is more complicated than you think. This can be the reason...
As your Rails project grows, you will accumulate a number of small patches. These will usually fix a bug in...
The attached ImageLoader helper will start fetching an image and return an image that is resolved once the image is...
Sometimes you want to preload images that you will be using later. E.g. if hovering over a an area changes...
You will need to look here and find your own device. Look for the "bootable CD" download, which will give...
Cucumber's docstrings let you add long strings to a step like this: # foo.feature Given this text: """ First line
Tool to show you which gems are slow to load: ➜ git:(master) ✗ bundle exec bumbler [################################################# ] (49/65) travis-lint...
Enter any command into explainshell and it will explain it to you: split into separate commands (if present), with each...
If you want to perform a failover on another haproxy backend server this is the way you should do it...
Stackprof is a sampling call-stack profile for Ruby 2.1+. Instead of tracking all method calls, it will simply collect...
You know that Devise offers RSpec test helpers for controller specs. However, in request specs, they will not work.
A very informative and interesting presentation about browsing performance, looking at efforts Google Chrome takes to increase it.
Table of contents of the linked article: What are Web Fonts? Advantages of Web Fonts Disadvantages of Web Fonts
Note This card does not reflect the current state of lazy loading technologies. The native lazy attribute could be used...
You want to test your 1GE or 10GE internet uplink? We needed to ensure we have full 10GE to the...
Rails 4 introduced raising an error on pending migrations. This is most annoying when you are crafting a migration but...
Our applications not only need to be functional, they need to be fast. But, to quote Donald Knuth, premature optimization...
Some tasks in a web application are better not done live when a user request a page, but in the...
I recommend install Node.js using nvm. This way you can have multiple Node versions in your ~/.nvm. You also won...
You have the following HTML structure:
If you want to run Javascript code whenever someone clicks on a ...
..., you...
Built-in matchers Get an overview of all the matchers that are built into RSpec. Play with some of...
Learn to store attachments in a way that is accessible by authorized users only Learn to prevent users from...
Exercise 1: Maps In MovieDB, add a new field “Principal filming location”. In a movie’s show view, geocode that...
Stepping forward from JavaScript Basics, the goal of this card is for you to be able to read and write...