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Action View Helpers
====================

After reading this guide, you will know:

* What helpers are provided by Action View.

--------------------------------------------------------------------------------

Overview of helpers provided by Action View
-------------------------------------------

WIP: Not all the helpers are listed here. For a full list see the [API documentation](https://api.rubyonrails.org/classes/ActionView/Helpers.html)

The following is only a brief overview summary of the helpers available in Action View. It's recommended that you review the [API Documentation](https://api.rubyonrails.org/classes/ActionView/Helpers.html), which covers all of the helpers in more detail, but this should serve as a good starting point.

### AssetTagHelper

This module provides methods for generating HTML that links views to assets such as images, JavaScript files, stylesheets, and feeds.

By default, Rails links to these assets on the current host in the public folder, but you can direct Rails to link to assets from a dedicated assets server by setting `config.action_controller.asset_host` in the application configuration, typically in `config/environments/production.rb`. For example, let's say your asset host is `assets.example.com`:

```ruby
config.action_controller.asset_host = "assets.example.com"
image_tag("rails.png") 
# => <img src="http://assets.example.com/images/rails.png" />
```

#### auto_discovery_link_tag

Returns a link tag that browsers and feed readers can use to auto-detect an RSS, Atom, or JSON feed.

```ruby
auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", { title: "RSS Feed" }) 
# => <link rel="alternate" type="application/rss+xml" title="RSS Feed" href="http://www.example.com/feed.rss" />
```

#### image_path

Computes the path to an image asset in the `app/assets/images` directory. Full paths from the document root will be passed through. Used internally by `image_tag` to build the image path.

```ruby
image_path("edit.png") # => /assets/edit.png
```

Fingerprint will be added to the filename if config.assets.digest is set to true.

```ruby
image_path("edit.png") 
# => /assets/edit-2d1a2db63fc738690021fedb5a65b68e.png
```

#### image_url

Computes the URL to an image asset in the `app/assets/images` directory. This will call `image_path` internally and merge with your current host or your asset host.

```ruby
image_url("edit.png") # => http://www.example.com/assets/edit.png
```

#### image_tag

Returns an HTML image tag for the source. The source can be a full path or a file that exists in your `app/assets/images` directory.

```ruby
image_tag("icon.png") # => <img src="/assets/icon.png" />
```

#### javascript_include_tag

Returns an HTML script tag for each of the sources provided. You can pass in the filename (`.js` extension is optional) of JavaScript files that exist in your `app/assets/javascripts` directory for inclusion into the current page or you can pass the full path relative to your document root.

```ruby
javascript_include_tag "common" 
# => <script src="/assets/common.js"></script>
```

#### javascript_path

Computes the path to a JavaScript asset in the `app/assets/javascripts` directory. If the source filename has no extension, `.js` will be appended. Full paths from the document root will be passed through. Used internally by `javascript_include_tag` to build the script path.

```ruby
javascript_path "common" # => /assets/common.js
```

#### javascript_url

Computes the URL to a JavaScript asset in the `app/assets/javascripts` directory. This will call `javascript_path` internally and merge with your current host or your asset host.

```ruby
javascript_url "common" 
# => http://www.example.com/assets/common.js
```

#### stylesheet_link_tag

Returns a stylesheet link tag for the sources specified as arguments. If you don't specify an extension, `.css` will be appended automatically.

```ruby
stylesheet_link_tag "application" 
# => <link href="/assets/application.css" media="screen" rel="stylesheet" />
```

#### stylesheet_path

Computes the path to a stylesheet asset in the `app/assets/stylesheets` directory. If the source filename has no extension, `.css` will be appended. Full paths from the document root will be passed through. Used internally by `stylesheet_link_tag` to build the stylesheet path.

```ruby
stylesheet_path "application" # => /assets/application.css
```

#### stylesheet_url

Computes the URL to a stylesheet asset in the `app/assets/stylesheets` directory. This will call `stylesheet_path` internally and merge with your current host or your asset host.

```ruby
stylesheet_url "application" 
# => http://www.example.com/assets/application.css
```

### AtomFeedHelper

#### atom_feed

This helper makes building an Atom feed easy. Here's a full usage example:

**config/routes.rb**

```ruby
resources :articles
```

**app/controllers/articles_controller.rb**

```ruby
def index
  @articles = Article.all

  respond_to do |format|
    format.html
    format.atom
  end
end
```

**app/views/articles/index.atom.builder**

```ruby
atom_feed do |feed|
  feed.title("Articles Index")
  feed.updated(@articles.first.created_at)

  @articles.each do |article|
    feed.entry(article) do |entry|
      entry.title(article.title)
      entry.content(article.body, type: 'html')

      entry.author do |author|
        author.name(article.author_name)
      end
    end
  end
end
```

### BenchmarkHelper

#### benchmark

Allows you to measure the execution time of a block in a template and records the result to the log. Wrap this block around expensive operations or possible bottlenecks to get a time reading for the operation.

```html+erb
<% benchmark "Process data files" do %>
  <%= expensive_files_operation %>
<% end %>
```

This would add something like "Process data files (0.34523)" to the log, which you can then use to compare timings when optimizing your code.

### CacheHelper

#### cache

A method for caching fragments of a view rather than an entire action or page. This technique is useful for caching pieces like menus, lists of news topics, static HTML fragments, and so on. This method takes a block that contains the content you wish to cache. See `AbstractController::Caching::Fragments` for more information.

```erb
<% cache do %>
  <%= render "shared/footer" %>
<% end %>
```

### CaptureHelper

#### capture

The `capture` method allows you to extract part of a template into a variable. You can then use this variable anywhere in your templates or layout.

```html+erb
<% @greeting = capture do %>
  <p>Welcome! The date and time is <%= Time.now %></p>
<% end %>
```

The captured variable can then be used anywhere else.

```html+erb
<html>
  <head>
    <title>Welcome!</title>
  </head>
  <body>
    <%= @greeting %>
  </body>
</html>
```

#### content_for

Calling `content_for` stores a block of markup in an identifier for later use. You can make subsequent calls to the stored content in other templates or the layout by passing the identifier as an argument to `yield`.

For example, let's say we have a standard application layout, but also a special page that requires certain JavaScript that the rest of the site doesn't need. We can use `content_for` to include this JavaScript on our special page without fattening up the rest of the site.

**app/views/layouts/application.html.erb**

```html+erb
<html>
  <head>
    <title>Welcome!</title>
    <%= yield :special_script %>
  </head>
  <body>
    <p>Welcome! The date and time is <%= Time.now %></p>
  </body>
</html>
```

**app/views/articles/special.html.erb**

```html+erb
<p>This is a special page.</p>

<% content_for :special_script do %>
  <script>alert('Hello!')</script>
<% end %>
```

### DateHelper

#### date_select

Returns a set of select tags (one for year, month, and day) pre-selected for accessing a specified date-based attribute.

```ruby
date_select("article", "published_on")
```

#### datetime_select

Returns a set of select tags (one for year, month, day, hour, and minute) pre-selected for accessing a specified datetime-based attribute.

```ruby
datetime_select("article", "published_on")
```

#### distance_of_time_in_words

Reports the approximate distance in time between two Time or Date objects or integers as seconds. Set `include_seconds` to true if you want more detailed approximations.

```ruby
distance_of_time_in_words(Time.now, Time.now + 15.seconds) 
# => less than a minute
distance_of_time_in_words(Time.now, Time.now + 15.seconds, include_seconds: true) 
# => less than 20 seconds
```

#### select_date

Returns a set of HTML select-tags (one for year, month, and day) pre-selected with the `date` provided.

```ruby
# Generates a date select that defaults to the date provided (six days after today)
select_date(Time.today + 6.days)

# Generates a date select that defaults to today (no specified date)
select_date()
```

#### select_datetime

Returns a set of HTML select-tags (one for year, month, day, hour, and minute) pre-selected with the `datetime` provided.

```ruby
# Generates a datetime select that defaults to the datetime provided (four days after today)
select_datetime(Time.now + 4.days)

# Generates a datetime select that defaults to today (no specified datetime)
select_datetime()
```

#### select_day

Returns a select tag with options for each of the days 1 through 31 with the current day selected.

```ruby
# Generates a select field for days that defaults to the day for the date provided
select_day(Time.today + 2.days)

# Generates a select field for days that defaults to the number given
select_day(5)
```

#### select_hour

Returns a select tag with options for each of the hours 0 through 23 with the current hour selected.

```ruby
# Generates a select field for hours that defaults to the hours for the time provided
select_hour(Time.now + 6.hours)
```

#### select_minute

Returns a select tag with options for each of the minutes 0 through 59 with the current minute selected.

```ruby
# Generates a select field for minutes that defaults to the minutes for the time provided.
select_minute(Time.now + 10.minutes)
```

#### select_month

Returns a select tag with options for each of the months January through December with the current month selected.

```ruby
# Generates a select field for months that defaults to the current month
select_month(Date.today)
```

#### select_second

Returns a select tag with options for each of the seconds 0 through 59 with the current second selected.

```ruby
# Generates a select field for seconds that defaults to the seconds for the time provided
select_second(Time.now + 16.seconds)
```

#### select_time

Returns a set of HTML select-tags (one for hour and minute).

```ruby
# Generates a time select that defaults to the time provided
select_time(Time.now)
```

#### select_year

Returns a select tag with options for each of the five years on each side of the current, which is selected. The five year radius can be changed using the `:start_year` and `:end_year` keys in the `options`.

```ruby
# Generates a select field for five years on either side of Date.today that defaults to the current year
select_year(Date.today)

# Generates a select field from 1900 to 2009 that defaults to the current year
select_year(Date.today, start_year: 1900, end_year: 2009)
```

#### time_ago_in_words

Like `distance_of_time_in_words`, but where `to_time` is fixed to `Time.now`.

```ruby
time_ago_in_words(3.minutes.from_now) # => 3 minutes
```

#### time_select

Returns a set of select tags (one for hour, minute, and optionally second) pre-selected for accessing a specified time-based attribute. The selects are prepared for multi-parameter assignment to an Active Record object.

```ruby
# Creates a time select tag that, when POSTed, will be stored in the order variable in the submitted attribute
time_select("order", "submitted")
```

### DebugHelper

Returns a `pre` tag that has object dumped by YAML. This creates a very readable way to inspect an object.

```ruby
my_hash = { 'first' => 1, 'second' => 'two', 'third' => [1,2,3] }
debug(my_hash)
```

```html
<pre class='debug_dump'>---
first: 1
second: two
third:
- 1
- 2
- 3
</pre>
```

### FormHelper

Form helpers are designed to make working with models much easier compared to using just standard HTML elements by providing a set of methods for creating forms based on your models. This helper generates the HTML for forms, providing a method for each sort of input (e.g., text, password, select, and so on). When the form is submitted (i.e., when the user hits the submit button or form.submit is called via JavaScript), the form inputs will be bundled into the params object and passed back to the controller.

There are two types of form helpers: those that specifically work with model attributes and those that don't. This helper deals with those that work with model attributes; to see an example of form helpers that don't work with model attributes, check the `ActionView::Helpers::FormTagHelper` documentation.

The core method of this helper, `form_with`, gives you the ability to create a form for a model instance; for example, let's say that you have a model Person and want to create a new instance of it:

```html+erb
<!-- Note: a @person variable will have been created in the controller (e.g. @person = Person.new) -->
<%= form_with model: @person do |form| %>
  <%= form.text_field :first_name %>
  <%= form.text_field :last_name %>
  <%= submit_tag 'Create' %>
<% end %>
```

The HTML generated for this would be:

```html
<form class="new_person" id="new_person" action="/people" accept-charset="UTF-8" method="post">
  <input name="utf8" type="hidden" value="&#x2713;" />
  <input type="hidden" name="authenticity_token" value="lTuvBzs7ANygT0NFinXj98tfw3Emfm65wwYLbUvoWsK2pngccIQSUorM2C035M9dZswXgWTvKwFS8W5TVblpYw==" />
  <input type="text" name="person[first_name]" id="person_first_name" />
  <input type="text" name="person[last_name]" id="person_last_name" />
  <input type="submit" name="commit" value="Create" data-disable-with="Create" />
</form>
```

The params object created when this form is submitted would look like:

```ruby
{"utf8" => "✓", "authenticity_token" => "lTuvBzs7ANygT0NFinXj98tfw3Emfm65wwYLbUvoWsK2pngccIQSUorM2C035M9dZswXgWTvKwFS8W5TVblpYw==", "person" => {"first_name" => "William", "last_name" => "Smith"}, "commit" => "Create", "controller" => "people", "action" => "create"}
```

The params hash has a nested person value, which can therefore be accessed with `params[:person]` in the controller.

#### check_box

Returns a checkbox tag tailored for accessing a specified attribute.

```ruby
# Let's say that @article.validated? is 1:
check_box("article", "validated")
# => <input type="checkbox" id="article_validated" name="article[validated]" value="1" />
#    <input name="article[validated]" type="hidden" value="0" />
```

#### fields_for

Creates a scope around a specific model object. This makes `fields_for` suitable for specifying additional model objects in the same form:

```html+erb
<%= form_with model: @person do |person_form| %>
  First name: <%= person_form.text_field :first_name %>
  Last name : <%= person_form.text_field :last_name %>

  <%= fields_for @person.permission do |permission_fields| %>
    Admin?  : <%= permission_fields.check_box :admin %>
  <% end %>
<% end %>
```

#### file_field

Returns a file upload input tag tailored for accessing a specified attribute.

```ruby
file_field(:user, :avatar)
# => <input type="file" id="user_avatar" name="user[avatar]" />
```

#### form_with

Creates a form builder to work with. If a `model` argument is specified, form fields will be scoped to that model, and form field values will be prepopulated with corresponding model attributes.

```html+erb
<%= form_with model: @article do |form| %>
  <%= form.label :title, 'Title' %>:
  <%= form.text_field :title %><br>
  <%= form.label :body, 'Body' %>:
  <%= form.text_area :body %><br>
<% end %>
```

#### hidden_field

Returns a hidden input tag tailored for accessing a specified attribute.

```ruby
hidden_field(:user, :token)
# => <input type="hidden" id="user_token" name="user[token]" value="#{@user.token}" />
```

#### label

Returns a label tag tailored for labelling an input field for a specified attribute.

```ruby
label(:article, :title)
# => <label for="article_title">Title</label>
```

#### password_field

Returns an input tag of the "password" type tailored for accessing a specified attribute.

```ruby
password_field(:login, :pass)
# => <input type="text" id="login_pass" name="login[pass]" value="#{@login.pass}" />
```

#### radio_button

Returns a radio button tag for accessing a specified attribute.

```ruby
# Let's say that @article.category returns "rails":
radio_button("article", "category", "rails")
radio_button("article", "category", "java")
# => <input type="radio" id="article_category_rails" name="article[category]" value="rails" checked="checked" />
#    <input type="radio" id="article_category_java" name="article[category]" value="java" />
```

#### text_area

Returns a textarea opening and closing tag set tailored for accessing a specified attribute.

```ruby
text_area(:comment, :text, size: "20x30")
# => <textarea cols="20" rows="30" id="comment_text" name="comment[text]">
#      #{@comment.text}
#    </textarea>
```

#### text_field

Returns an input tag of the "text" type tailored for accessing a specified attribute.

```ruby
text_field(:article, :title)
# => <input type="text" id="article_title" name="article[title]" value="#{@article.title}" />
```

#### email_field

Returns an input tag of the "email" type tailored for accessing a specified attribute.

```ruby
email_field(:user, :email)
# => <input type="email" id="user_email" name="user[email]" value="#{@user.email}" />
```

#### url_field

Returns an input tag of the "url" type tailored for accessing a specified attribute.

```ruby
url_field(:user, :url)
# => <input type="url" id="user_url" name="user[url]" value="#{@user.url}" />
```

### FormOptionsHelper

Provides a number of methods for turning different kinds of containers into a set of option tags.

#### collection_select

Returns `select` and `option` tags for the collection of existing return values of `method` for `object`'s class.

Example object structure for use with this method:

```ruby
class Article < ApplicationRecord
  belongs_to :author
end

class Author < ApplicationRecord
  has_many :articles
  def name_with_initial
    "#{first_name.first}. #{last_name}"
  end
end
```

Sample usage (selecting the associated Author for an instance of Article, `@article`):

```ruby
collection_select(:article, :author_id, Author.all, :id, :name_with_initial, { prompt: true })
```

If `@article.author_id` is 1, this would return:

```html
<select name="article[author_id]">
  <option value="">Please select</option>
  <option value="1" selected="selected">D. Heinemeier Hansson</option>
  <option value="2">D. Thomas</option>
  <option value="3">M. Clark</option>
</select>
```

#### collection_radio_buttons

Returns `radio_button` tags for the collection of existing return values of `method` for `object`'s class.

Example object structure for use with this method:

```ruby
class Article < ApplicationRecord
  belongs_to :author
end

class Author < ApplicationRecord
  has_many :articles
  def name_with_initial
    "#{first_name.first}. #{last_name}"
  end
end
```

Sample usage (selecting the associated Author for an instance of Article, `@article`):

```ruby
collection_radio_buttons(:article, :author_id, Author.all, :id, :name_with_initial)
```

If `@article.author_id` is 1, this would return:

```html
<input id="article_author_id_1" name="article[author_id]" type="radio" value="1" checked="checked" />
<label for="article_author_id_1">D. Heinemeier Hansson</label>
<input id="article_author_id_2" name="article[author_id]" type="radio" value="2" />
<label for="article_author_id_2">D. Thomas</label>
<input id="article_author_id_3" name="article[author_id]" type="radio" value="3" />
<label for="article_author_id_3">M. Clark</label>
```

Recovering some option passed (e.g. programmatically checking an object from collection):

```ruby
collection_radio_buttons(:article, :author_id, Author.all, :id, :name_with_initial, {checked: Author.last})
```

In this case, the last object from the collection will be checked:

```html
<input id="article_author_id_1" name="article[author_id]" type="radio" value="1" />
<label for="article_author_id_1">D. Heinemeier Hansson</label>
<input id="article_author_id_2" name="article[author_id]" type="radio" value="2" />
<label for="article_author_id_2">D. Thomas</label>
<input id="article_author_id_3" name="article[author_id]" type="radio" value="3" checked="checked" />
<label for="article_author_id_3">M. Clark</label>
```

To access the passed options programmatically (e.g. adding a custom class if checked):

**Sample html.erb**

```html+erb
<%= collection_radio_buttons(:article, :author_id, Author.all, :id, :name_with_initial, {checked: Author.last, required: true} do |rb| %>
      <%= rb.label(class: "#{'my-custom-class' if rb.value == Author.last.id}") { rb.radio_button + rb.text } %>
<% end %>
```


#### collection_check_boxes

Returns `check_box` tags for the collection of existing return values of `method` for `object`'s class.

Example object structure for use with this method:

```ruby
class Article < ApplicationRecord
  has_and_belongs_to_many :authors
end

class Author < ApplicationRecord
  has_and_belongs_to_many :articles
  def name_with_initial
    "#{first_name.first}. #{last_name}"
  end
end
```

Sample usage (selecting the associated Authors for an instance of Article, `@article`):

```ruby
collection_check_boxes(:article, :author_ids, Author.all, :id, :name_with_initial)
```

If `@article.author_ids` is [1], this would return:

```html
<input id="article_author_ids_1" name="article[author_ids][]" type="checkbox" value="1" checked="checked" />
<label for="article_author_ids_1">D. Heinemeier Hansson</label>
<input id="article_author_ids_2" name="article[author_ids][]" type="checkbox" value="2" />
<label for="article_author_ids_2">D. Thomas</label>
<input id="article_author_ids_3" name="article[author_ids][]" type="checkbox" value="3" />
<label for="article_author_ids_3">M. Clark</label>
<input name="article[author_ids][]" type="hidden" value="" />
```

#### option_groups_from_collection_for_select

Returns a string of `option` tags, like `options_from_collection_for_select`, but groups them by `optgroup` tags based on the object relationships of the arguments.

Example object structure for use with this method:

```ruby
class Continent < ApplicationRecord
  has_many :countries
  # attribs: id, name
end

class Country < ApplicationRecord
  belongs_to :continent
  # attribs: id, name, continent_id
end
```

Sample usage:

```ruby
option_groups_from_collection_for_select(@continents, :countries, :name, :id, :name, 3)
```

Possible output:

```html
<optgroup label="Africa">
  <option value="1">Egypt</option>
  <option value="4">Rwanda</option>
  ...
</optgroup>
<optgroup label="Asia">
  <option value="3" selected="selected">China</option>
  <option value="12">India</option>
  <option value="5">Japan</option>
  ...
</optgroup>
```

NOTE: Only the `optgroup` and `option` tags are returned, so you still have to wrap the output in an appropriate `select` tag.

#### options_for_select

Accepts a container (hash, array, enumerable, your type) and returns a string of option tags.

```ruby
options_for_select([ "VISA", "MasterCard" ])
# => <option>VISA</option> <option>MasterCard</option>
```

NOTE: Only the `option` tags are returned, you have to wrap this call in a regular HTML `select` tag.

#### options_from_collection_for_select

Returns a string of option tags that have been compiled by iterating over the `collection` and assigning the result of a call to the `value_method` as the option value and the `text_method` as the option text.

```ruby
options_from_collection_for_select(collection, value_method, text_method, selected = nil)
```

For example, imagine a loop iterating over each person in `@project.people` to generate an input tag:

```ruby
options_from_collection_for_select(@project.people, "id", "name")
# => <option value="#{person.id}">#{person.name}</option>
```

NOTE: Only the `option` tags are returned, you have to wrap this call in a regular HTML `select` tag.

#### select

Create a select tag and a series of contained option tags for the provided object and method.

Example:

```ruby
select("article", "person_id", Person.all.collect { |p| [ p.name, p.id ] }, { include_blank: true })
```

If `@article.person_id` is 1, this would become:

```html
<select name="article[person_id]">
  <option value="" label=" "></option>
  <option value="1" selected="selected">David</option>
  <option value="2">Eileen</option>
  <option value="3">Rafael</option>
</select>
```

#### time_zone_options_for_select

Returns a string of option tags for pretty much any time zone in the world.

#### time_zone_select

Returns select and option tags for the given object and method, using `time_zone_options_for_select` to generate the list of option tags.

```ruby
time_zone_select("user", "time_zone")
```

#### date_field

Returns an input tag of the "date" type tailored for accessing a specified attribute.

```ruby
date_field("user", "dob")
```

### FormTagHelper

Provides a number of methods for creating form tags that are not scoped to model objects. Instead, you provide the names and values manually.

#### check_box_tag

Creates a check box form input tag.

```ruby
check_box_tag 'accept'
# => <input id="accept" name="accept" type="checkbox" value="1" />
```

#### field_set_tag

Creates a field set for grouping HTML form elements.

```html+erb
<%= field_set_tag do %>
  <p><%= text_field_tag 'name' %></p>
<% end %>
# => <fieldset><p><input id="name" name="name" type="text" /></p></fieldset>
```

#### file_field_tag

Creates a file upload field.

```html+erb
<%= form_with url: new_account_avatar_path(@account), multipart: true do %>
  <label for="file">Avatar:</label> <%= file_field_tag 'avatar' %>
  <%= submit_tag %>
<% end %>
```

Example output:

```ruby
file_field_tag 'attachment'
# => <input id="attachment" name="attachment" type="file" />
```

#### hidden_field_tag

Creates a hidden form input field used to transmit data that would be lost due to HTTP's statelessness or data that should be hidden from the user.

```ruby
hidden_field_tag 'token', 'VUBJKB23UIVI1UU1VOBVI@'
# => <input id="token" name="token" type="hidden" value="VUBJKB23UIVI1UU1VOBVI@" />
```

#### image_submit_tag

Displays an image which when clicked will submit the form.

```ruby
image_submit_tag("login.png")
# => <input src="/images/login.png" type="image" />
```

#### label_tag

Creates a label field.

```ruby
label_tag 'name'
# => <label for="name">Name</label>
```

#### password_field_tag

Creates a password field, a masked text field that will hide the users input behind a mask character.

```ruby
password_field_tag 'pass'
# => <input id="pass" name="pass" type="password" />
```

#### radio_button_tag

Creates a radio button; use groups of radio buttons named the same to allow users to select from a group of options.

```ruby
radio_button_tag 'favorite_color', 'maroon'
# => <input id="favorite_color_maroon" name="favorite_color" type="radio" value="maroon" />
```

#### select_tag

Creates a dropdown selection box.

```ruby
select_tag "people", "<option>David</option>"
# => <select id="people" name="people"><option>David</option></select>
```

#### submit_tag

Creates a submit button with the text provided as the caption.

```ruby
submit_tag "Publish this article"
# => <input name="commit" type="submit" value="Publish this article" />
```

#### text_area_tag

Creates a text input area; use a textarea for longer text inputs such as blog posts or descriptions.

```ruby
text_area_tag 'article'
# => <textarea id="article" name="article"></textarea>
```

#### text_field_tag

Creates a standard text field; use these text fields to input smaller chunks of text like a username or a search query.

```ruby
text_field_tag 'name'
# => <input id="name" name="name" type="text" />
```

#### email_field_tag

Creates a standard input field of email type.

```ruby
email_field_tag 'email'
# => <input id="email" name="email" type="email" />
```

#### url_field_tag

Creates a standard input field of url type.

```ruby
url_field_tag 'url'
# => <input id="url" name="url" type="url" />
```

#### date_field_tag

Creates a standard input field of date type.

```ruby
date_field_tag "dob"
# => <input id="dob" name="dob" type="date" />
```

### JavaScriptHelper

Provides functionality for working with JavaScript in your views.

#### escape_javascript

Escape carrier returns and single and double quotes for JavaScript segments.

#### javascript_tag

Returns a JavaScript tag wrapping the provided code.

```ruby
javascript_tag "alert('All is good')"
```

```html
<script>
//<![CDATA[
alert('All is good')
//]]>
</script>
```

### NumberHelper

Provides methods for converting numbers into formatted strings. Methods are provided for phone numbers, currency, percentage, precision, positional notation, and file size.

#### number_to_currency

Formats a number into a currency string (e.g., $13.65).

```ruby
number_to_currency(1234567890.50) # => $1,234,567,890.50
```

#### number_to_human_size

Formats the bytes in size into a more understandable representation; useful for reporting file sizes to users.

```ruby
number_to_human_size(1234)    # => 1.2 KB
number_to_human_size(1234567) # => 1.2 MB
```

#### number_to_percentage

Formats a number as a percentage string.

```ruby
number_to_percentage(100, precision: 0) # => 100%
```

#### number_to_phone

Formats a number into a phone number (US by default).

```ruby
number_to_phone(1235551234) # => 123-555-1234
```

#### number_with_delimiter

Formats a number with grouped thousands using a delimiter.

```ruby
number_with_delimiter(12345678) # => 12,345,678
```

#### number_with_precision

Formats a number with the specified level of `precision`, which defaults to 3.

```ruby
number_with_precision(111.2345)               # => 111.235
number_with_precision(111.2345, precision: 2) # => 111.23
```

### SanitizeHelper

The SanitizeHelper module provides a set of methods for scrubbing text of undesired HTML elements.

#### sanitize

This sanitize helper will HTML encode all tags and strip all attributes that aren't specifically allowed.

```ruby
sanitize @article.body
```

If either the `:attributes` or `:tags` options are passed, only the mentioned attributes and tags are allowed and nothing else.

```ruby
sanitize @article.body, tags: %w(table tr td), attributes: %w(id class style)
```

To change defaults for multiple uses, for example adding table tags to the default:

```ruby
class Application < Rails::Application
  config.action_view.sanitized_allowed_tags = 'table', 'tr', 'td'
end
```

#### sanitize_css(style)

Sanitizes a block of CSS code.

#### strip_links(html)
Strips all link tags from text leaving just the link text.

```ruby
strip_links('<a href="https://rubyonrails.org">Ruby on Rails</a>')
# => Ruby on Rails
```

```ruby
strip_links('emails to <a href="mailto:me@email.com">me@email.com</a>.')
# => emails to me@email.com.
```

```ruby
strip_links('Blog: <a href="http://myblog.com/">Visit</a>.')
# => Blog: Visit.
```

#### strip_tags(html)

Strips all HTML tags from the html, including comments.
This functionality is powered by the rails-html-sanitizer gem.

```ruby
strip_tags("Strip <i>these</i> tags!")
# => Strip these tags!
```

```ruby
strip_tags("<b>Bold</b> no more!  <a href='more.html'>See more</a>")
# => Bold no more!  See more
```

NB: The output may still contain unescaped '<', '>', '&' characters and confuse browsers.

### UrlHelper

Provides methods to make links and get URLs that depend on the routing subsystem.

#### url_for

Returns the URL for the set of `options` provided.

##### Examples

```ruby
url_for @profile
# => /profiles/1

url_for [ @hotel, @booking, page: 2, line: 3 ]
# => /hotels/1/bookings/1?line=3&page=2
```

#### link_to

Links to a URL derived from `url_for` under the hood. Primarily used to
create RESTful resource links, which for this example, boils down to
when passing models to `link_to`.

**Examples**

```ruby
link_to "Profile", @profile
# => <a href="/profiles/1">Profile</a>
```

You can use a block as well if your link target can't fit in the name parameter. ERB example:

```html+erb
<%= link_to @profile do %>
  <strong><%= @profile.name %></strong> -- <span>Check it out!</span>
<% end %>
```

would output:

```html
<a href="/profiles/1">
  <strong>David</strong> -- <span>Check it out!</span>
</a>
```

See [the API Documentation for more information](https://api.rubyonrails.org/classes/ActionView/Helpers/UrlHelper.html#method-i-link_to)

#### button_to

Generates a form that submits to the passed URL. The form has a submit button
with the value of the `name`.

##### Examples

```html+erb
<%= button_to "Sign in", sign_in_path %>
```

would roughly output something like:

```html
<form method="post" action="/sessions" class="button_to">
  <input type="submit" value="Sign in" />
</form>
```

See [the API Documentation for more information](https://api.rubyonrails.org/classes/ActionView/Helpers/UrlHelper.html#method-i-button_to)

### CsrfHelper

Returns meta tags "csrf-param" and "csrf-token" with the name of the cross-site
request forgery protection parameter and token, respectively.

```html
<%= csrf_meta_tags %>
```

NOTE: Regular forms generate hidden fields so they do not use these tags. More
details can be found in the [Rails Security Guide](security.html#cross-site-request-forgery-csrf).
