When you run code inside a $watch expression that forces a repaint (e.g. by computing an element's width, or running something like element.is(':visible')) you may end up with "page flickering" or scroll offset changes.

You can hook to the end of a digest cycle to avoid that.

The following is basically straight from the docs, but pretty awkward to use. Do it...

Option 0: Download from the official page (preferred)

• Open https://googlechromelabs.github.io/chrome-for-testing/
• In Section "Stable" > chromedriver / linux64 > Download ZIP from URL
• Take the chromedriver binary from the ZIP file and put it e.g. into ~/bin.

Chromedriver must be available in your path. You can add ~/bin to your path like this:

echo "export PATH=$PATH:$HOME/bin" >> $HOME/.bash_profile

If you're also using Geordi, disable automatic updating of chromedriver in ~/.config/geordi/global.yml:

a...

If you get one of this errors:

Error: Could not retrieve catalog from remote server: Error 400 on SERVER: (<unknown>): found character that cannot start any token while scanning for the next token at line 1297 column 3
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

Error: Could not retrieve catalog from remote server: Error 400 on SERVER: undefined method `empty?' for nil:NilClass at /etc/puppet/environments/production/manifests/nodes.pp:1 on node example.makandra.de
Warning: ...

When putting phone numbers into web pages, you should use tel: links so smartphone users can click those numbers to call someone.

Here is a small helper method that you can use to simplify this:

def tel_to(text)
  groups = text.to_s.scan(/(?:^\+)?\d+/)
  link_to text, "tel:#{groups.join '-'}"
end

This will allow you to use human-readable numbers and get clean links:

>> tel_to '(01234) 555 6789'
=> <a href="tel:01234-555-6789">(01234) 555 6789</a>

>> tel_to '+1 555 123-456'
=> <a href="tel:+1-555-123-456...

Raphaël is a small JavaScript library that should simplify your work with vector graphics on the web. If you want to create your own specific chart or image crop and rotate widget, for example, you can achieve it simply and easily with this library.

Upgrading from Ruby 1.8.7 to 2.1.2 took me an hour for a medium-sized application. It involved hardly any changes except

• removing the occasional monkey patch where I had backported functionality from modern Rubies
• Migrating from require to require_relative where I loaded RSpec factories in Cucumber's env.rb (the Rails application root is no longer in the load path by default)
• replacing the old debugger with byebug
• removing sytem_timer from Gemfile (see [this SO thread](http://stackoverflow.com/questions/7850216/how-to-inst...

Cucumber allows for prose in features and scenarios. Example:

Feature: Cancel account

  There are several ways to cancel a user account. Admins need to 
  do it in complex cases, but normally, users can do it themselves.
  
  Scenario: User cancels his own account
    
    Users should be able to cancel an account themselves, so the 
    admins do not need to do it.
    
    Given a user account for "willy@astor.de"
    When I sign in as "willy@astor.de"
    And I follow "Cancel account"
    Then I should see "Account canceled"...

If you make a gem with Bundler, you will get a rake release task that will instantly publish your gem to rubygems.org for all the world to admire. For private gems this is very bad.

To make sure this cannot happen, rubygems 2.2+ allows you to restrict eligible push hosts:

Gem::Specification.new 'my_gem', '1.0' do |s|
  # ...
  s.metadata['allowed_push_host'] = 'https://gems.my-company.example'
end

In case you already messed up, [follow these instructions to get your gem removed](http://help.rubygems.org/kb/rubygems/removing-an-a...

This is a problem when using Selenium with Firefox. We recommend using ChromeDriver for your Selenium tests.

Firefox will not trigger focus/blur events when its window is not focused. While this makes sense in standard usage, it breaks in parallel test execution.

Please do not rely on focus events in your tests. The linked card has an example of how to build passing tests that deal with focus/blur events.

Using this gem I could get JSON generation from a large, nested Ruby hash down from 200ms to 2ms.

Its behavior differs from the default JSON.dump or to_json behavior in that it serializes Ruby symbols as ":symbol", and that it doesn't like an ActiveSupport::HasWithIndifferentAccess.

There are also some issues if you are on Rails < 4.1 and want it to replace #to_json (but you can always just call Oj.dump explicitely).

Security warning: Oj does not escape HTML entities in JSON
---------...

Firefox 5.0.1, which we were using for most Rails 2.3 projects, does not run on Ubuntu 14.04 any more. Here is how to update affected projects.

1. Update (or create) .firefox-version with the content: 24.0
   If you haven't installed Firefox 24 yet, the next time you run tests with Geordi, it will tell you how to install it.

2. On a Rails 2 project:

   • Update your Cucumber-related gems as described in Upgrading Cucumber and Capybara, including cucumber_spinner and launchy.

   • If you...

Just install the texlive-xetex package:

sudo apt-get install texlive-xetex

Running integration tests without texlive-xetex will produce an error during xelatex execution:

RTeX::Document::ExecutableNotFoundError

JavaScript's NaN ("Not a Number") is hard to compare against. It never equals anything, not even itself:

NaN === NaN;        // false
Number.NaN === NaN; // false

There is the isNaN method, but it is not really what you are looking for:

isNaN(NaN)     // true
isNaN('hello') // true

Option 1: ES6

The Object.is() method determines whether two values are the same value. It even works for NaN:

Object.is(NaN, NaN) // true

Option 2: ES5

The example above shows that simply using isNaN would match other ...

Since we are using LoDash instead of UnderscoreJS in recent/current projects, you should keep in mind that their syntax is a bit different.

UnderscoreJS

In UnderscoreJS, methods always return a value:

x = [1, 2, 2]
_.uniq(x) // => [1, 2]
_(x).uniq() // => [1, 2]

If you want to chain multiple calls, you need to start off with a _.chain, and call value() to terminate the chain.

_.chain(x).uniq().map(function(i) { return i + 10 }).reverse().value() // => [12, 11]

##...

bower-rails is a great solution for managing vendored assets in your Rails app. It feels especially much more convenient and easier to update assets when going this way.

bower-rails generates a Bowerfile that works much like the Gemfile you're used to. Just specify your dependencies and run rake bower:install. You can find available packages here.

An example Bowerfile:

# ./Bowerfile
asset 'angular'
asset 'angular-i18n'
asset 'angular-ui-router'
asset 'angu...

JavaScript structures that include circular references can't be serialized with a"plain" JSON.stringify. Example:

a = { name: 'Groucho' };
b = { name: 'Harpo', sibling: a };
a.sibling = b;

Doing a JSON.stringify(a) will throw an error:

TypeError: Converting circular structure to JSON

There is not much you can do about that except specifying a custom serializer function that detects and cleans up circular references. There are existing solutions so you do not need to think of one yourself, like <https://githu...

Creating records in specs can be so fast that two records created instantly after one another might have the same created_at timestamp (especially since those timestamps don't have an indefinitely high resolution). When ordering lists by timestamps, you should therefore always include a final order condition using the primary key of the table.

class Photo < ActiveRecord::Base
  scope :by_date, -> { order('created_at DESC, id DESC') }
end

Photo.by_date

Remember to include the id field in the database index.

This may be hard to find in the docs, but if you want CoffeeScript classes that instantiate their properties from a hash of attributes (like ActiveRecord), do it like this:

class User
  constructor: ({ @name, @email }) ->
    # empty contstructor is fine, CoffeeScript will do the magic.

Example:

var batman = new User(name: 'Bruce Wayne', email: 'batman@example.com')
batman.name # => 'Bruce Wayne'

This is what worked for me in a Rails 4:

# JSON data as first argument, then parameters
patch :update, { some: 'data' }.to_json, id: id, format: :json

Usage:

class Document < ActiveRecord::Base
  scope :any_tags, -> (tags){ where('tags && ARRAY[?]', tags) }
  scope :all_tags, -> (tags){ where('tags @> ARRAY[?]', tags) }
end

Document.create(title: "PostgreSQL", tags: ["pg","rails"])

Document.any_tags('pg')
Document.all_tags(['pg', 'rails'])

Migration:

class CreateDocuments < ActiveRecord::Migration
  def change
    create_table :documents do |t|
      t.string :title
      t.string :tags, array: true, default: []
      t.timestamps
    end
    add_index  :documents, :ta...

tl;dr: Use with_index

ActiveRecord's find_each with index

If you do not provide a block to find_each, it will return an Enumerator for chaining with other methods:

Person.find_each.with_index do |person, index|
  person.award_trophy(index + 1)
end

Ruby's map with index

Similarly, you may need an index when using other methods, like map, flat_map, detect (when you need the index for detection), or similar. Here is an example for map:

people...

Nice tutorial about packaging Ruby bindings to your API in a Ruby gem, with tests using VCR casettes.

To avoid n+1 queries, you want to eager-load associated records if you know you need to access them later on.

The Rails docs say:

Eager loading is supported with polymorphic associations.

This is true, but has some caveats.

Example

Consider the following models:

class Image < ActiveRecord::Base; end

class Video < ActiveRecord::Base; end

class PageVersion < ActiveRecord::Base
  belongs_to :primary_medium, polymorphic: true # may be Image or Video
end

class Page < ActiveRecord::Base
  belongs_to ...