You probably know that you can use CSS selectors to match against elements and their attributes, such as:

a[title] { /* any <a> that has a "title" */ }
a[data-fancy="true"] { /* any <a> that has their "data-fancy" attribute set to "true" */ }

But there is more: You do not need to match against "full" attribute values but can match against parts of them.

They work in all somewhat modern browsers, and IE9 or later.

Match variants

Exact match (CSS2)

[foo="bar"] (matches `<div foo="b...

You can use the content CSS attribute to set an element's content -- which is especially useful for the :before and :after pseudo elements:

a:before {
  content: 'Click me: ';
}

The above example would prepend "Click me:" to any link on the page.

Note that you can also refer the contents of other attributes of the element. So, if your links have a helpful title set, you could do this:

a:before {
  content: attr(title) ": ";
}

There also is a jsFiddle for the examp...

Ruby has two different ways to match the start and the end of a text:

• ^ (Start of line) and $ (End of line)
• \A (Start of string) and \z (End of string)

Most often you want to use \A and \z.

Here is a short example in which we want to validate the content type of a file attachment. Normally we would not expect content_type_1 to be a valid content type with the used regular expression image\/(jpeg|png). But as ^ and $ will match lines, it matches both content_type_1 and content_type_2. Using \A and \z will wo...

Virtualization

Microsoft provides virtual machines for different Internet Explorer versions.

The images are available for various virtualization solutions, including VirtualBox.

BrowserStack

For a monthly fee browserstack.com provides access to various versions of Windows and Internet Explorer through your web browser. It's pretty convenient.

By installing a Chrome addon you can ...

Spreewald now comes with a step that tests if a form field is visible:

Then the "Due date" field should be visible
But the "Author" field should not be visible

The step works by looking up the field for the given label, then checks if that field is hidden via CSS (or Javascript).

It is not currently tested if the label is visible or hidden. For this see: [Check that an element is visible or hidden via CSS with Cucumber/Capybara](https://makandracards.com/makandra/1049-check-that-an-elem...

Consul 0.6.1+ gives your Power class a number of static methods that behave neutrally in case Power.current is nil. This allows you to create authorization-aware models that still work when there is no user at the end of a web browser, e.g. on the console, during tests or during batch processes.

You will often want to access Power.current from another model, to e.g. iterate through the list of accessible users:

class UserReport

  def data
    Power.current.users.c...

We recently had a problem on a Memcache cluster, where one of the servers showed a significantly worse cache hit rate and a lot more evictions.

It turned out that the only reason was that the server was running for a few months longer than the others. Some investigation showed this to be a known problem with Memcache: Once your cache gets full, it might be "hardwired" for your specific usage patterns. If those change (and you for example start to store larger values), memory is no longer allocated optimally, in extreme cases Memcache might ...

The problem

Calling bundle update GEMNAME will update a lot more gems than you think. E.g. when you do this:

bundle update cucumber-rails

... you might think this will only update cucumber-rails. But it actually updates cucumber-rails and all of its dependencies. This will explode in your face when one of these dependencies release a new version with breaking API changes. Which is all the time.

In the example above updating cucumber-rails will give you Capybara 2.0 (because capybara is a dependency of `cucumber-rail...

Calling bundle update (without arguments) updates all your gems at once. Given that many gems don't care about stable APIs, this might break your application in a million ways.

To stay sane, update your gems using the applicable way below:

Projects in active development

Update the entire bundle regularily (e.g. once a week). This ensures that your libraries are up-to-date while it's easy to spot major version bumps which may break the app.

Projects that have not been updated in a while

1. [Update a single gem conservatively](htt...

If you get a message like this:

Jan 21 13:42:38 foobar syslogd: /var/log/authlog : no such file or directory

But you are sure the file exists and it have the correct permissions:

# example for Solaris 9
-rw-r--r-- 1 root sys 8,0K 21. Jan 13:51 /var/log/authlog

Then you perhaps have a trailing whitespace after /var/log/authlog in the /etc/syslog.conf.

Note: Use TAB to separate log components from log file names in Solaris. Because spaces do not work.

Apache HTTP server benchmarking tool (ab) is a nice tool to test performance on sites delivered by HTTP. If the site you're about to test is placed behind a login, follow these steps to successfully use ab on it.

1. Open the site to test in the browser of your choice. Do not login yet.
2. Use developer tools to show all cookies used by the site. (Chrome: Ctrl+Shift+i, open the 'Resources' tab and click on the site below 'Cookies' on the left. Firefox: Right-click on the site, open 'We...

Example input:

li.active a:link

Example output (specificity):

| 0 | 2 | 2 |

See also: https://www.codecaptain.io/tools/css-specificity-calculator

Every time you call $(...) jQuery will create a new object. Because of this, comparing two jQuery collections with == will never return true, even when they are wrapping the same native DOM elements:

$('body') == $('body') // false

In order to test if two jQuery objects refer to the same native DOM elements, use is:

var $a = $('body');
var $b = $('body');
$a.is($b); // true

Jasmine equality matcher for jQuery

See [here](/makandra/34925-jasmine-testing-complex-types-for-e...

Examples how to create dozens of shapes using pure CSS and a single HTML element.

When doing a git blame, git will blame the person who added or removed white space in a line (e.g. by indenting), not the person who originally wrote the code.

Say git blame -w to ignore such white-space changes. You want this. \
Note that you can also use it when diffing: git diff -w.

Example

Consider this method, created by a user in commit d47bf443:

def hello
  'world'
end

^

$ git blame foo
d47bf443 (Arne Hartherz 2012-12-19 14:44:38 +0100 1) def hello
d47bf443 (Arne Hartherz 2012-12-19 14:44:38 +0100 2...

Axlsx is an incredible gem to generate "Office Open XML" spreadsheet files (XLSX). Does not break on large spreadsheets and supports a ton of features like graphs.

API looks mature and existing code is easy to migrate when coming from the spreadsheet gem.
The documentation of some methods is a bit out of date, but you'll find your way around the gem's code.

No support for reading files, however. :( If you want to open XLSX spreadsheets (for example to confirm your output in tests), you can use [roo](h...

You can define methods in any example group using Ruby's def keyword or define_method method. These helper methods are exposed to examples in the group in which they are defined and groups nested within that group, but not parent or sibling groups.

jquery-timing is a very useful jquery plugin that helps to remove lots of nested anonymous functions. It's API provides you some methods that help you to write readable and understandable method chains. See yourself:

Example

// before
$('.some').show().children().doThat();
window.setTimeout(function(){
  $('some').children().doSomething().hide(function() {
    window.setTimeout(function() {
      otherStuffToDo();
    }, 1000);
  });
}, 500);

// after
$('.some').s...

As attachments to this card you will find a Cucumber feature and supplementing step definition that you can use to provoke Selenium focus issues that only occur when two focus-sensitive Selenium scenarios run at the same time (probably with parallel_tests). This can help you to detect and fix flickering integration tests.

The attached feature works by going to your root_path and focusing a random form element every 5...

Sometimes you want to see what data you get through a TCP or UDP connection.
For example, you want to know how a HTTP Request look like.

It's very easy with netcat.

Example to listen on port 80 and the output gets to stdout.

sudo nc -kl 80

It's also possible write it into a file:

sudo nc -kl 80 > output.txt

If you use Ports higher than 1000 you don't need to be root (sudo).

The bash offers control over the behavior of autocompletion.

The most primitive example is this (just run it in your bash; if you want it available everywhere, put the complete ... line into your .bashrc):

> complete -W "list of all words for an automatic completion" command_to_be_completed
> command_to_be_completed a<TAB>
all an automatic

With complete you define how the specified command shall be completed. For basic needs, -W (as in "word list") should be enough, but you may also specify a function, a glob patte...