21 files changed, 126 insertions, 85 deletions

diff --git a/guides/source/active_record_basics.md b/guides/source/active_record_basics.md
index 6b3aa471f9..2ac80d8f89 100644
--- a/guides/source/active_record_basics.md
+++ b/guides/source/active_record_basics.md
@@ -314,8 +314,8 @@ already in the database, follows a specific format and many more.
 
 Validation is a very important issue to consider when persisting to the database, so
 the methods `save` and `update` take it into account when
-running: they return `false` when validation fails and they didn't actually
-perform any operation on the database. All of these have a bang counterpart (that
+running: they return `false` when validation fails and they don't actually
+perform any operations on the database. All of these have a bang counterpart (that
 is, `save!` and `update!`), which are stricter in that
 they raise the exception `ActiveRecord::RecordInvalid` if validation fails.
 A quick example to illustrate:
diff --git a/guides/source/active_record_postgresql.md b/guides/source/active_record_postgresql.md
index 6d07291b07..8543fcd20f 100644
--- a/guides/source/active_record_postgresql.md
+++ b/guides/source/active_record_postgresql.md
@@ -84,7 +84,7 @@ Book.where("array_length(ratings, 1) >= 3")
 ### Hstore
 
 * [type definition](http://www.postgresql.org/docs/current/static/hstore.html)
-* [functions and operators](http://www.postgresql.org/docs/current/static/hstore.html#AEN167712)
+* [functions and operators](http://www.postgresql.org/docs/current/static/hstore.html#AEN179902)
 
 NOTE: You need to enable the `hstore` extension to use hstore.
 
@@ -114,16 +114,21 @@ Profile.where("settings->'color' = ?", "yellow")
 # => #<ActiveRecord::Relation [#<Profile id: 1, settings: {"color"=>"yellow", "resolution"=>"1280x1024"}>]>
 ```
 
-### JSON
+### JSON and JSONB
 
 * [type definition](http://www.postgresql.org/docs/current/static/datatype-json.html)
 * [functions and operators](http://www.postgresql.org/docs/current/static/functions-json.html)
 
 ```ruby
 # db/migrate/20131220144913_create_events.rb
+# ... for json datatype:
 create_table :events do |t|
   t.json 'payload'
 end
+# ... or for jsonb datatype:
+create_table :events do |t|
+  t.jsonb 'payload'
+end
 
 # app/models/event.rb
 class Event < ApplicationRecord
@@ -285,7 +290,7 @@ SELECT n.nspname AS enum_schema,
 ### UUID
 
 * [type definition](http://www.postgresql.org/docs/current/static/datatype-uuid.html)
-* [pgcrypto generator function](http://www.postgresql.org/docs/current/static/pgcrypto.html#AEN159361)
+* [pgcrypto generator function](http://www.postgresql.org/docs/current/static/pgcrypto.html#AEN182570)
 * [uuid-ossp generator functions](http://www.postgresql.org/docs/current/static/uuid-ossp.html)
 
 NOTE: You need to enable the `pgcrypto` (only PostgreSQL >= 9.4) or `uuid-ossp`
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 3676462788..215142223d 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -513,8 +513,6 @@ Article.where(author: author)
 Author.joins(:articles).where(articles: { author: author })
 ```
 
-NOTE: The values cannot be symbols. For example, you cannot do `Client.where(status: :active)`.
-
 #### Range Conditions
 
 ```ruby
diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md
index 5313361dfd..6eb5de78be 100644
--- a/guides/source/active_record_validations.md
+++ b/guides/source/active_record_validations.md
@@ -953,7 +953,7 @@ should happen, an `Array` can be used. Moreover, you can apply both `:if` and
 ```ruby
 class Computer < ApplicationRecord
   validates :mouse, presence: true,
-                    if: ["market.retail?", :desktop?],
+                    if: [Proc.new  { |c| c.market.retail? }, :desktop?],
                     unless: Proc.new { |c| c.trackpad.present? }
 end
 ```
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index 67bed4c8da..23f53ac084 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -755,6 +755,8 @@ NOTE: Defined in `active_support/core_ext/module/anonymous.rb`.
 
 ### Method Delegation
 
+#### `delegate`
+
 The macro `delegate` offers an easy way to forward methods.
 
 Let's imagine that users in some application have login information in the `User` model but name and other data in a separate `Profile` model:
@@ -837,13 +839,32 @@ In the previous example the macro generates `avatar_size` rather than `size`.
 
 NOTE: Defined in `active_support/core_ext/module/delegation.rb`
 
+#### `delegate_missing_to`
+
+Imagine you would like to delegate everything missing from the `User` object,
+to the `Profile` one. The `delegate_missing_to` macro lets you implement this
+in a breeze:
+
+```ruby
+class User < ApplicationRecord
+  has_one :profile
+
+  delegate_missing_to :profile
+end
+```
+
+The target can be anything callable within the object, e.g. instance variables,
+methods, constants, etc. Only the public methods of the target are delegated.
+
+NOTE: Defined in `active_support/core_ext/module/delegation.rb`.
+
 ### Redefining Methods
 
 There are cases where you need to define a method with `define_method`, but don't know whether a method with that name already exists. If it does, a warning is issued if they are enabled. No big deal, but not clean either.
 
 The method `redefine_method` prevents such a potential warning, removing the existing method before if needed.
 
-NOTE: Defined in `active_support/core_ext/module/remove_method.rb`
+NOTE: Defined in `active_support/core_ext/module/remove_method.rb`.
 
 Extensions to `Class`
 ---------------------
@@ -931,7 +952,7 @@ When `:instance_reader` is `false`, the instance predicate returns a `NoMethodEr
 
 If you do not want the instance predicate, pass `instance_predicate: false` and it will not be defined.
 
-NOTE: Defined in `active_support/core_ext/class/attribute.rb`
+NOTE: Defined in `active_support/core_ext/class/attribute.rb`.
 
 #### `cattr_reader`, `cattr_writer`, and `cattr_accessor`
 
@@ -940,8 +961,7 @@ The macros `cattr_reader`, `cattr_writer`, and `cattr_accessor` are analogous to
 ```ruby
 class MysqlAdapter < AbstractAdapter
   # Generates class methods to access @@emulate_booleans.
-  cattr_accessor :emulate_booleans
-  self.emulate_booleans = true
+  cattr_accessor :emulate_booleans, default: true
 end
 ```
 
@@ -950,8 +970,7 @@ Instance methods are created as well for convenience, they are just proxies to t
 ```ruby
 module ActionView
   class Base
-    cattr_accessor :field_error_proc
-    @@field_error_proc = Proc.new{ ... }
+    cattr_accessor :field_error_proc, default: Proc.new { ... }
   end
 end
 ```
@@ -963,7 +982,7 @@ Also, you can pass a block to `cattr_*` to set up the attribute with a default v
 ```ruby
 class MysqlAdapter < AbstractAdapter
   # Generates class methods to access @@emulate_booleans with default value of true.
-  cattr_accessor(:emulate_booleans) { true }
+  cattr_accessor :emulate_booleans, default: true
 end
 ```
 
@@ -1829,7 +1848,7 @@ as well as adding or subtracting their results from a Time object. For example:
 (4.months + 5.years).from_now
 ```
 
-NOTE: Defined in `active_support/core_ext/numeric/time.rb`
+NOTE: Defined in `active_support/core_ext/numeric/time.rb`.
 
 ### Formatting
 
diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md
index 22b6b278d7..a02eebf263 100644
--- a/guides/source/asset_pipeline.md
+++ b/guides/source/asset_pipeline.md
@@ -447,15 +447,15 @@ For example, a new Rails application includes a default
 
 ```js
 // ...
-//= require jquery
-//= require jquery_ujs
+//= require rails-ujs
+//= require turbolinks
 //= require_tree .
 ```
 
 In JavaScript files, Sprockets directives begin with `//=`. In the above case,
 the file is using the `require` and the `require_tree` directives. The `require`
 directive is used to tell Sprockets the files you wish to require. Here, you are
-requiring the files `jquery.js` and `jquery_ujs.js` that are available somewhere
+requiring the files `rails-ujs.js` and `turbolinks.js` that are available somewhere
 in the search path for Sprockets. You need not supply the extensions explicitly.
 Sprockets assumes you are requiring a `.js` file when done from within a `.js`
 file.
@@ -572,20 +572,6 @@ would generate this HTML:
 
 The `body` param is required by Sprockets.
 
-### Runtime Error Checking
-
-By default the asset pipeline will check for potential errors in development mode during
-runtime. To disable this behavior you can set:
-
-```ruby
-config.assets.raise_runtime_errors = false
-```
-
-When this option is true, the asset pipeline will check if all the assets loaded
-in your application are included in the `config.assets.precompile` list.
-If `config.assets.digest` is also true, the asset pipeline will require that
-all requests for assets include digests.
-
 ### Raise an Error When an Asset is Not Found
 
 If you are using sprockets-rails >= 3.2.0 you can configure what happens
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index 5c7d1f5365..bead931529 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -960,7 +960,7 @@ class Author < ApplicationRecord
 end
 ```
 
-NOTE: You only need to specify the :counter_cache option on the `belongs_to`
+NOTE: You only need to specify the `:counter_cache` option on the `belongs_to`
 side of the association.
 
 Counter cache columns are added to the containing model's list of read-only attributes through `attr_readonly`.
@@ -1831,7 +1831,7 @@ The `limit` method lets you restrict the total number of objects that will be fe
 class Author < ApplicationRecord
   has_many :recent_books,
     -> { order('published_at desc').limit(100) },
-    class_name: "Book",
+    class_name: "Book"
 end
 ```
 
diff --git a/guides/source/command_line.md b/guides/source/command_line.md
index 3360496c08..9fddbf76b6 100644
--- a/guides/source/command_line.md
+++ b/guides/source/command_line.md
@@ -262,12 +262,12 @@ $ bin/rails db:migrate
 ==  CreateHighScores: migrated (0.0019s) ======================================
 ```
 
-INFO: Let's talk about unit tests. Unit tests are code that tests and makes assertions 
-about code. In unit testing, we take a little part of code, say a method of a model, 
-and test its inputs and outputs. Unit tests are your friend. The sooner you make 
-peace with the fact that your quality of life will drastically increase when you unit 
-test your code, the better. Seriously. Please visit 
-[the testing guide](http://guides.rubyonrails.org/testing.html) for an in-depth 
+INFO: Let's talk about unit tests. Unit tests are code that tests and makes assertions
+about code. In unit testing, we take a little part of code, say a method of a model,
+and test its inputs and outputs. Unit tests are your friend. The sooner you make
+peace with the fact that your quality of life will drastically increase when you unit
+test your code, the better. Seriously. Please visit
+[the testing guide](http://guides.rubyonrails.org/testing.html) for an in-depth
 look at unit testing.
 
 Let's see the interface Rails created for us.
@@ -533,7 +533,8 @@ The `tmp:` namespaced tasks will help you clear and create the `Rails.root/tmp`
 
 * `rails tmp:cache:clear` clears `tmp/cache`.
 * `rails tmp:sockets:clear` clears `tmp/sockets`.
-* `rails tmp:clear` clears all cache and sockets files.
+* `rails tmp:screenshots:clear` clears `tmp/screenshots`.
+* `rails tmp:clear` clears all cache, sockets and screenshot files.
 * `rails tmp:create` creates tmp directories for cache, sockets and pids.
 
 ### Miscellaneous
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 1234e1f192..21b3ca0efa 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -157,8 +157,6 @@ defaults to `:debug` for all environments. The available log levels are: `:debug
 * `config.assets.enabled` a flag that controls whether the asset
 pipeline is enabled. It is set to `true` by default.
 
-* `config.assets.raise_runtime_errors` Set this flag to `true` to enable additional runtime error checking. Recommended in `config/environments/development.rb` to minimize unexpected behavior when deploying to `production`.
-
 * `config.assets.css_compressor` defines the CSS compressor to use. It is set by default by `sass-rails`. The unique alternative value at the moment is `:yui`, which uses the `yui-compressor` gem.
 
 * `config.assets.js_compressor` defines the JavaScript compressor to use. Possible values are `:closure`, `:uglifier` and `:yui` which require the use of the `closure-compiler`, `uglifier` or `yui-compressor` gems respectively.
diff --git a/guides/source/development_dependencies_install.md b/guides/source/development_dependencies_install.md
index 7ec038eb4d..c57efd6362 100644
--- a/guides/source/development_dependencies_install.md
+++ b/guides/source/development_dependencies_install.md
@@ -62,7 +62,7 @@ $ sudo apt-get install sqlite3 libsqlite3-dev
 If you are on Fedora or CentOS, you're done with
 
 ```bash
-$ sudo yum install sqlite3 sqlite3-devel
+$ sudo yum install libsqlite3x libsqlite3x-devel 
 ```
 
 If you are on Arch Linux, you will need to run:
diff --git a/guides/source/documents.yaml b/guides/source/documents.yaml
index 2afef57fc2..59205ee465 100644
--- a/guides/source/documents.yaml
+++ b/guides/source/documents.yaml
@@ -130,11 +130,6 @@
       url: active_support_instrumentation.html
       description: This guide explains how to use the instrumentation API inside of Active Support to measure events inside of Rails and other Ruby code.
     -
-      name: Profiling Rails Applications
-      work_in_progress: true
-      url: profiling.html
-      description: This guide explains how to profile your Rails applications to improve performance.
-    -
       name: Using Rails for API-only Applications
       url: api_app.html
       description: This guide explains how to effectively use Rails to develop a JSON API application.
diff --git a/guides/source/generators.md b/guides/source/generators.md
index d4ed2355d4..be1be75e7a 100644
--- a/guides/source/generators.md
+++ b/guides/source/generators.md
@@ -689,14 +689,6 @@ Available options are:
 * `:env` - Specifies the environment in which to run this rake task.
 * `:sudo` - Whether or not to run this task using `sudo`. Defaults to `false`.
 
-### `capify!`
-
-Runs the `capify` command from Capistrano at the root of the application which generates Capistrano configuration.
-
-```ruby
-capify!
-```
-
 ### `route`
 
 Adds text to the `config/routes.rb` file:
diff --git a/guides/source/getting_started.md b/guides/source/getting_started.md
index 49c691c841..2ed1883ede 100644
--- a/guides/source/getting_started.md
+++ b/guides/source/getting_started.md
@@ -1546,8 +1546,8 @@ You'll learn a little about associations in the next section of this guide.
 
 The (`:references`) keyword used in the bash command is a special data type for models.
 It creates a new column on your database table with the provided model name appended with an `_id`
-that can hold integer values. You can get a better understanding after analyzing the
-`db/schema.rb` file below.
+that can hold integer values. To get a better understanding, analyze the
+`db/schema.rb` file after running the migration.
 
 In addition to the model, Rails has also made a migration to create the
 corresponding database table:
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index 6c8706bc13..aa2b7d1ba9 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -701,9 +701,11 @@ end
 
 ### Pluralization
 
-In English there are only one singular and one plural form for a given string, e.g. "1 message" and "2 messages". Other languages ([Arabic](http://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html#ar), [Japanese](http://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html#ja), [Russian](http://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html#ru) and many more) have different grammars that have additional or fewer [plural forms](http://cldr.unicode.org/index/cldr-spec/plural-rules). Thus, the I18n API provides a flexible pluralization feature.
+In many languages — including English — there are only two forms, a singular and a plural, for
+a given string, e.g. "1 message" and "2 messages". Other languages ([Arabic](http://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html#ar), [Japanese](http://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html#ja), [Russian](http://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html#ru) and many more) have different grammars that have additional or fewer [plural forms](http://cldr.unicode.org/index/cldr-spec/plural-rules). Thus, the I18n API provides a flexible pluralization feature.
 
-The `:count` interpolation variable has a special role in that it both is interpolated to the translation and used to pick a pluralization from the translations according to the pluralization rules defined by CLDR:
+The `:count` interpolation variable has a special role in that it both is interpolated to the translation and used to pick a pluralization from the translations according to the pluralization rules defined in the
+pluralization backend. By default, only the English pluralization rules are applied.
 
 ```ruby
 I18n.backend.store_translations :en, inbox: {
@@ -733,6 +735,22 @@ The translation denoted as `:one` is regarded as singular, and the `:other` is u
 
 If the lookup for the key does not return a Hash suitable for pluralization, an `I18n::InvalidPluralizationData` exception is raised.
 
+#### Locale-specific rules
+
+The I18n gem provides a Pluralization backend that can be used to enable locale-specific rules. Include it
+to the Simple backend, then add the localized pluralization algorithms to translation store, as `i18n.plural.rule`.
+
+```ruby
+I18n::Backend::Simple.include(I18n::Backend::Pluralization)
+I18n.backend.store_translations :pt, i18n: { plural: { rule: lambda { |n| [0, 1].include?(n) ? :one : :other } } }
+I18n.backend.store_translations :pt, apples: { one: 'one or none', other: 'more than one' }
+
+I18n.t :apples, count: 0, locale: :pt
+# => 'one or none'
+```
+
+Alternatively, the separate gem [rails-i18n](https://github.com/svenfuchs/rails-i18n) can be used to provide a fuller set of locale-specific pluralization rules.
+
 ### Setting and Passing a Locale
 
 The locale can be either set pseudo-globally to `I18n.locale` (which uses `Thread.current` like, e.g., `Time.zone`) or can be passed as an option to `#translate` and `#localize`.
diff --git a/guides/source/initialization.md b/guides/source/initialization.md
index 3ea156c6fe..86aea2c24d 100644
--- a/guides/source/initialization.md
+++ b/guides/source/initialization.md
@@ -155,7 +155,7 @@ defined here to find the matching command.
 ### `rails/command.rb`
 
 When one types a Rails command, `invoke` tries to lookup a command for the given
-namespace and executing the command if found.
+namespace and executes the command if found.
 
 If Rails doesn't recognize the command, it hands the reins over to Rake
 to run a task of the same name.
diff --git a/guides/source/layouts_and_rendering.md b/guides/source/layouts_and_rendering.md
index caa3d21d23..76b325d0bf 100644
--- a/guides/source/layouts_and_rendering.md
+++ b/guides/source/layouts_and_rendering.md
@@ -221,7 +221,7 @@ service requests that are expecting something other than proper HTML.
 
 NOTE: By default, if you use the `:plain` option, the text is rendered without
 using the current layout. If you want Rails to put the text into the current
-layout, you need to add the `layout: true` option and use the `.txt.erb`
+layout, you need to add the `layout: true` option and use the `.text.erb`
 extension for the layout file.
 
 #### Rendering HTML
@@ -379,6 +379,7 @@ Rails understands both numeric status codes and the corresponding symbols shown
 |                     | 415              | :unsupported_media_type          |
 |                     | 416              | :range_not_satisfiable           |
 |                     | 417              | :expectation_failed              |
+|                     | 421              | :misdirected_request             |
 |                     | 422              | :unprocessable_entity            |
 |                     | 423              | :locked                          |
 |                     | 424              | :failed_dependency               |
@@ -386,6 +387,7 @@ Rails understands both numeric status codes and the corresponding symbols shown
 |                     | 428              | :precondition_required           |
 |                     | 429              | :too_many_requests               |
 |                     | 431              | :request_header_fields_too_large |
+|                     | 451              | :unavailable_for_legal_reasons   |
 | **Server Error**    | 500              | :internal_server_error           |
 |                     | 501              | :not_implemented                 |
 |                     | 502              | :bad_gateway                     |
@@ -1171,7 +1173,7 @@ To pass a local variable to a partial in only specific cases use the `local_assi
 
 This way it is possible to use the partial without the need to declare all local variables.
 
-Every partial also has a local variable with the same name as the partial (minus the underscore). You can pass an object in to this local variable via the `:object` option:
+Every partial also has a local variable with the same name as the partial (minus the leading underscore). You can pass an object in to this local variable via the `:object` option:
 
 ```erb
 <%= render partial: "customer", object: @new_customer %>
diff --git a/guides/source/plugins.md b/guides/source/plugins.md
index 760ff431c0..8c2d56ceb8 100644
--- a/guides/source/plugins.md
+++ b/guides/source/plugins.md
@@ -340,8 +340,7 @@ module Yaffle
 
     module ClassMethods
       def acts_as_yaffle(options = {})
-        cattr_accessor :yaffle_text_field
-        self.yaffle_text_field = (options[:yaffle_text_field] || :last_squawk).to_s
+        cattr_accessor :yaffle_text_field, default: (options[:yaffle_text_field] || :last_squawk).to_s
       end
     end
   end
@@ -411,8 +410,7 @@ module Yaffle
 
     module ClassMethods
       def acts_as_yaffle(options = {})
-        cattr_accessor :yaffle_text_field
-        self.yaffle_text_field = (options[:yaffle_text_field] || :last_squawk).to_s
+        cattr_accessor :yaffle_text_field, default: (options[:yaffle_text_field] || :last_squawk).to_s
 
         include Yaffle::ActsAsYaffle::LocalInstanceMethods
       end
diff --git a/guides/source/security.md b/guides/source/security.md
index f69a0c72b0..297680b176 100644
--- a/guides/source/security.md
+++ b/guides/source/security.md
@@ -1060,6 +1060,7 @@ Additional Resources
 
 The security landscape shifts and it is important to keep up to date, because missing a new vulnerability can be catastrophic. You can find additional resources about (Rails) security here:
 
-* Subscribe to the Rails security [mailing list](http://groups.google.com/group/rubyonrails-security)
-* [Keep up to date on the other application layers](http://secunia.com/) (they have a weekly newsletter, too)
-* A [good security blog](https://www.owasp.org) including the [Cross-Site scripting Cheat Sheet](https://www.owasp.org/index.php/DOM_based_XSS_Prevention_Cheat_Sheet)
+* Subscribe to the Rails security [mailing list.](http://groups.google.com/group/rubyonrails-security)
+* [Brakeman - Rails Security Scanner](http://brakemanscanner.org/) - To perform static security analysis for Rails applications.
+* [Keep up to date on the other application layers.](http://secunia.com/) (they have a weekly newsletter, too)
+* A [good security blog](https://www.owasp.org) including the [Cross-Site scripting Cheat Sheet.](https://www.owasp.org/index.php/DOM_based_XSS_Prevention_Cheat_Sheet)
diff --git a/guides/source/testing.md b/guides/source/testing.md
index e4fc8c7b6e..7abf3af187 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -602,11 +602,8 @@ Model tests don't have their own superclass like `ActionMailer::TestCase` instea
 System Testing
 --------------
 
-System tests are full-browser tests that can be used to test your application's
-JavaScript and user experience. System tests use Capybara as a base.
-
-System tests allow for running tests in either a real browser or a headless
-driver for testing full user interactions with your application.
+System tests allow you to test user interactions with your application, running tests
+in either a real or a headless browser. System tests uses Capybara under the hood.
 
 For creating Rails system tests, you use the `test/system` directory in your
 application. Rails provides a generator to create a system test skeleton for you.
@@ -660,8 +657,9 @@ end
 
 The driver name is a required argument for `driven_by`. The optional arguments
 that can be passed to `driven_by` are `:using` for the browser (this will only
-be used by Selenium), and `:screen_size` to change the size of the screen for
-screenshots.
+be used by Selenium), `:screen_size` to change the size of the screen for
+screenshots, and `:options` which can be used to set options supported by the
+driver.
 
 ```ruby
 require "test_helper"
@@ -671,8 +669,9 @@ class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
 end
 ```
 
-If your Capybara configuration requires more setup than provided by Rails, all
-of that configuration can be put into the `application_system_test_case.rb` file.
+If your Capybara configuration requires more setup than provided by Rails, this
+additional configuration could be added into the `application_system_test_case.rb`
+file.
 
 Please see [Capybara's documentation](https://github.com/teamcapybara/capybara#setup)
 for additional settings.
@@ -695,9 +694,9 @@ take a screenshot of the browser.
 Now we're going to add a system test to our blog application. We'll demonstrate
 writing a system test by visiting the index page and creating a new blog article.
 
-If you used the scaffold generator, a system test skeleton is automatically
-created for you. If you did not use the generator start by creating a system
-test skeleton.
+If you used the scaffold generator, a system test skeleton was automatically
+created for you. If you didn't use the scaffold generator, start by creating a
+system test skeleton.
 
 ```bash
 $ bin/rails generate system_test articles
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 93864db141..88a7d0a464 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -238,7 +238,7 @@ Run `bin/rails` to see the list of commands available.
 ### `ActionController::Parameters` No Longer Inherits from `HashWithIndifferentAccess`
 
 Calling `params` in your application will now return an object instead of a hash. If your
-parameters are already permitted, then you will not need to make any changes. If you are using `slice`
+parameters are already permitted, then you will not need to make any changes. If you are using `map`
 and other methods that depend on being able to read the hash regardless of `permitted?` you will
 need to upgrade your application to first permit and then convert to a hash.
 
diff --git a/guides/source/working_with_javascript_in_rails.md b/guides/source/working_with_javascript_in_rails.md
index 290f2a509b..ed27752a06 100644
--- a/guides/source/working_with_javascript_in_rails.md
+++ b/guides/source/working_with_javascript_in_rails.md
@@ -376,6 +376,35 @@ browser to submit the form via normal means (i.e. non-AJAX submission) will be
 canceled and the form will not be submitted at all. This is useful for
 implementing your own AJAX file upload workaround.
 
+### Rails-ujs event handlers
+
+Rails 5.1 introduced rails-ujs and dropped jQuery as a dependency.
+As a result the Unobtrusive JavaScript (UJS) driver has been rewritten to operate without jQuery.
+These introductions cause small changes to `custom events` fired during the request:
+
+NOTE: Signature of calls to UJS’s event handlers has changed.
+Unlike the version with jQuery, all custom events return only one parameter: `event`.
+In this parameter, there is an additional attribute `detail` which contains an array of extra parameters.
+
+| Event name          | Extra parameters (event.detail) | Fired                                                       |
+|---------------------|---------------------------------|-------------------------------------------------------------|
+| `ajax:before`       |                                 | Before the whole ajax business.                             |
+| `ajax:beforeSend`   | [xhr, options]                  | Before the request is sent.                                 |
+| `ajax:send`         | [xhr]                           | When the request is sent.                                   |
+| `ajax:stopped`      |                                 | When the request is stopped.                                |
+| `ajax:success`      | [response, status, xhr]         | After completion, if the response was a success.            |
+| `ajax:error`        | [response, status, xhr]         | After completion, if the response was an error.             |
+| `ajax:complete`     | [xhr, status]                   | After the request has been completed, no matter the outcome.|
+
+Example usage:
+
+```html
+document.body.addEventListener('ajax:success', function(event) {
+  var detail = event.detail;
+  var data = detail[0], status = detail[1],  xhr = detail[2];
+})
+```
+
 Server-Side Concerns
 --------------------