Module: ActionView::Helpers::JavaScriptHelper

Included in:
UrlHelper
Defined in:
lib/action_view/helpers/javascript_helper.rb

Overview

Provides a set of helpers for calling JavaScript functions and, most importantly, to call remote methods using what has been labelled AJAX. This means that you can call actions in your controllers without reloading the page, but still update certain parts of it using injections into the DOM. The common use case is having a form that adds a new element to a list without reloading the page.

To be able to use the JavaScript helpers, you must include the Prototype JavaScript Framework and for some functions script.aculo.us (which both come with Rails) on your pages. Choose one of these options:

  • Use <%= javascript_include_tag :defaults %> in the HEAD section of your page (recommended): The function will return references to the JavaScript files created by the rails command in your public/javascripts directory. Using it is recommended as the browser can then cache the libraries instead of fetching all the functions anew on every request.

  • Use <%= javascript_include_tag 'prototype' %>: As above, but will only include the Prototype core library, which means you are able to use all basic AJAX functionality. For the script.aculo.us-based JavaScript helpers, like visual effects, autocompletion, drag and drop and so on, you should use the method described above.

  • Use <%= define_javascript_functions %>: this will copy all the JavaScript support functions within a single script block.

For documentation on javascript_include_tag see ActionView::Helpers::AssetTagHelper.

If you're the visual type, there's an AJAX movie demonstrating the use of form_remote_tag.

Constant Summary collapse

CALLBACKS =
[:uninitialized, :loading, :loaded, :interactive, :complete, :failure, :success].push((100..599).to_a).flatten
AJAX_OPTIONS =
[ :before, :after, :condition, :url, :asynchronous, :method, 
:insertion, :position, :form, :with, :update, :script ].concat(CALLBACKS)
JAVASCRIPT_PATH =
File.join(File.dirname(__FILE__), 'javascripts')

Instance Method Summary collapse

Instance Method Details

#define_javascript_functionsObject

Includes the Action Pack JavaScript libraries inside a single <script> tag. The function first includes prototype.js and then its core extensions, (determined by filenames starting with “prototype”). Afterwards, any additional scripts will be included in random order.

Note: The recommended approach is to copy the contents of lib/action_view/helpers/javascripts/ into your application's public/javascripts/ directory, and use javascript_include_tag to create remote <script> links.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 299

def define_javascript_functions
  javascript = '<script type="text/javascript">'
  
  # load prototype.js and its extensions first 
  prototype_libs = Dir.glob(File.join(JAVASCRIPT_PATH, 'prototype*')).sort.reverse
  prototype_libs.each do |filename| 
    javascript << "\n" << IO.read(filename)
  end
  
  # load other librairies
  (Dir.glob(File.join(JAVASCRIPT_PATH, '*')) - prototype_libs).each do |filename| 
    javascript << "\n" << IO.read(filename)
  end
  javascript << '</script>'
end

#draggable_element(element_id, options = {}) ⇒ Object

Makes the element with the DOM ID specified by element_id draggable.

This method requires the inclusion of the script.aculo.us JavaScript library.

Example:

<%= draggable_element("my_image", :revert => true)

You can change the behaviour with various options, see script.aculo.us for more documentation.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 423

def draggable_element(element_id, options = {})
  javascript_tag("new Draggable('#{element_id}', #{options_for_javascript(options)})")
end

#drop_receiving_element(element_id, options = {}) ⇒ Object

Makes the element with the DOM ID specified by element_id receive dropped draggable elements (created by draggable_element). and make an AJAX call By default, the action called gets the DOM ID of the element as parameter.

This method requires the inclusion of the script.aculo.us JavaScript library.

Example:

<%= drop_receiving_element("my_cart", :url => { :controller => "cart", :action => "add" }) %>

You can change the behaviour with various options, see script.aculo.us for more documentation.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 439

def drop_receiving_element(element_id, options = {})
  options[:with]     ||= "'id=' + encodeURIComponent(element.id)"
  options[:onDrop]   ||= "function(element){" + remote_function(options) + "}"
  options.delete_if { |key, value| AJAX_OPTIONS.include?(key) }
  
  options[:accept] = array_or_string_for_javascript(options[:accept]) if options[:accept]    
  options[:hoverclass] = "'#{options[:hoverclass]}'" if options[:hoverclass]
  
  javascript_tag("Droppables.add('#{element_id}', #{options_for_javascript(options)})")
end

#escape_javascript(javascript) ⇒ Object

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


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# File 'lib/action_view/helpers/javascript_helper.rb', line 451

def escape_javascript(javascript)
  (javascript || '').gsub(/\r\n|\n|\r/, "\\n").gsub(/["']/) { |m| "\\#{m}" }
end

#evaluate_remote_responseObject

Returns 'eval(request.responseText)' which is the Javascript function that form_remote_tag can call in :complete to evaluate a multiple update return document using update_element_function calls.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 250

def evaluate_remote_response
  "eval(request.responseText)"
end

#form_remote_tag(options = {}) ⇒ Object

Returns a form tag that will submit using XMLHttpRequest in the background instead of the regular reloading POST arrangement. Even though it's using JavaScript to serialize the form elements, the form submission will work just like a regular submission as viewed by the receiving side (all elements available in @params). The options for specifying the target with :url and defining callbacks is the same as link_to_remote.

A “fall-through” target for browsers that doesn't do JavaScript can be specified with the :action/:method options on :html

form_remote_tag :html => { :action => url_for(:controller => "some", :action => "place") }

The Hash passed to the :html key is equivalent to the options (2nd) argument in the FormTagHelper.form_tag method.

By default the fall-through action is the same as the one specified in the :url (and the default method is :post).


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# File 'lib/action_view/helpers/javascript_helper.rb', line 158

def form_remote_tag(options = {})
  options[:form] = true

  options[:html] ||= {}
  options[:html][:onsubmit] = "#{remote_function(options)}; return false;"
  options[:html][:action] = options[:html][:action] || url_for(options[:url])
  options[:html][:method] = options[:html][:method] || "post"

  tag("form", options[:html], true)
end

#javascript_cdata_section(content) ⇒ Object

:nodoc:


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# File 'lib/action_view/helpers/javascript_helper.rb', line 461

def javascript_cdata_section(content) #:nodoc:
  "\n//#{cdata_section("\n#{content}\n//")}\n"
end

#javascript_tag(content) ⇒ Object

Returns a JavaScript tag with the content inside. Example:

javascript_tag "alert('All is good')" # => <script type="text/javascript">alert('All is good')</script>

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# File 'lib/action_view/helpers/javascript_helper.rb', line 457

def javascript_tag(content)
  ("script", javascript_cdata_section(content), :type => "text/javascript")
end

Returns a link that'll trigger a javascript function using the onclick handler and return false after the fact.

Examples:

link_to_function "Greeting", "alert('Hello world!')"
link_to_function(image_tag("delete"), "if confirm('Really?'){ do_delete(); }")

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# File 'lib/action_view/helpers/javascript_helper.rb', line 42

def link_to_function(name, function, html_options = {})
  (
    "a", name, 
    {:href => "#", :onclick => "#{function}; return false;"}.merge(html_options.symbolize_keys)
  )
end

Returns a link to a remote action defined by options[:url] (using the url_for format) that's called in the background using XMLHttpRequest. The result of that request can then be inserted into a DOM object whose id can be specified with options[:update]. Usually, the result would be a partial prepared by the controller with either render_partial or render_partial_collection.

Examples:

link_to_remote "Delete this post", :update => "posts", :url => { :action => "destroy", :id => post.id }
link_to_remote(image_tag("refresh"), :update => "emails", :url => { :action => "list_emails" })

You can also specify a hash for options[:update] to allow for easy redirection of output to an other DOM element if a server-side error occurs:

Example:

link_to_remote "Delete this post",
    :url => { :action => "destroy", :id => post.id },
    :update => { :success => "posts", :failure => "error" }

Optionally, you can use the options[:position] parameter to influence how the target DOM element is updated. It must be one of :before, :top, :bottom, or :after.

By default, these remote requests are processed asynchronous during which various JavaScript callbacks can be triggered (for progress indicators and the likes). All callbacks get access to the request object, which holds the underlying XMLHttpRequest.

To access the server response, use request.responseText, to find out the HTTP status, use request.status.

Example:

link_to_remote word,
    :url => { :action => "undo", :n => word_counter },
    :complete => "undoRequestCompleted(request)"

The callbacks that may be specified are (in order):

:loading

Called when the remote document is being loaded with data by the browser.

:loaded

Called when the browser has finished loading the remote document.

:interactive

Called when the user can interact with the remote document, even though it has not finished loading.

:success

Called when the XMLHttpRequest is completed, and the HTTP status code is in the 2XX range.

:failure

Called when the XMLHttpRequest is completed, and the HTTP status code is not in the 2XX range.

:complete

Called when the XMLHttpRequest is complete (fires after success/failure if they are present).,

You can further refine :success and :failure by adding additional callbacks for specific status codes:

Example:

link_to_remote word,
    :url => { :action => "action" },
    404 => "alert('Not found...? Wrong URL...?')",
    :failure => "alert('HTTP Error ' + request.status + '!')"

A status code callback overrides the success/failure handlers if present.

If you for some reason or another need synchronous processing (that'll block the browser while the request is happening), you can specify options[:type] = :synchronous.

You can customize further browser side call logic by passing in JavaScript code snippets via some optional parameters. In their order of use these are:

:confirm

Adds confirmation dialog.

:condition

Perform remote request conditionally by this expression. Use this to describe browser-side conditions when request should not be initiated.

:before

Called before request is initiated.

:after

Called immediately after request was initiated and before :loading.

:submit

Specifies the DOM element ID that's used as the parent of the form elements. By default this is the current form, but it could just as well be the ID of a table row or any other DOM element.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 134

def link_to_remote(name, options = {}, html_options = {})  
  link_to_function(name, remote_function(options), html_options)
end

#observe_field(field_id, options = {}) ⇒ Object

Observes the field with the DOM ID specified by field_id and makes an AJAX call when its contents have changed.

Required options are:

:url

url_for-style options for the action to call when the field has changed.

Additional options are:

:frequency

The frequency (in seconds) at which changes to this field will be detected. Not setting this option at all or to a value equal to or less than zero will use event based observation instead of time based observation.

:update

Specifies the DOM ID of the element whose innerHTML should be updated with the XMLHttpRequest response text.

:with

A JavaScript expression specifying the parameters for the XMLHttpRequest. This defaults to 'value', which in the evaluated context refers to the new field value.

Additionally, you may specify any of the options documented in link_to_remote.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 338

def observe_field(field_id, options = {})
  if options[:frequency] and options[:frequency] > 0
    build_observer('Form.Element.Observer', field_id, options)
  else
    build_observer('Form.Element.EventObserver', field_id, options)
  end
end

#observe_form(form_id, options = {}) ⇒ Object

Like observe_field, but operates on an entire form identified by the DOM ID form_id. options are the same as observe_field, except the default value of the :with option evaluates to the serialized (request string) value of the form.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 350

def observe_form(form_id, options = {})
  if options[:frequency]
    build_observer('Form.Observer', form_id, options)
  else
    build_observer('Form.EventObserver', form_id, options)
  end
end

#periodically_call_remote(options = {}) ⇒ Object

Periodically calls the specified url (options[:url]) every options[:frequency] seconds (default is 10). Usually used to update a specified div (options[:update]) with the results of the remote call. The options for specifying the target with :url and defining callbacks is the same as link_to_remote.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 141

def periodically_call_remote(options = {})
   frequency = options[:frequency] || 10 # every ten seconds by default
   code = "new PeriodicalExecuter(function() {#{remote_function(options)}}, #{frequency})"
   javascript_tag(code)
end

#remote_function(options) ⇒ Object

Returns the javascript needed for a remote function. Takes the same arguments as link_to_remote.

Example:

<select id="options" onchange="<%= remote_function(:update => "options", :url => { :action => :update_options }) %>">
  <option value="0">Hello</option>
  <option value="1">World</option>
</select>

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# File 'lib/action_view/helpers/javascript_helper.rb', line 262

def remote_function(options)
  javascript_options = options_for_ajax(options)

  update = ''
  if options[:update] and options[:update].is_a?Hash
    update  = []
    update << "success:'#{options[:update][:success]}'" if options[:update][:success]
    update << "failure:'#{options[:update][:failure]}'" if options[:update][:failure]
    update  = '{' + update.join(',') + '}'
  elsif options[:update]
    update << "'#{options[:update]}'"
  end

  function = update.empty? ? 
    "new Ajax.Request(" :
    "new Ajax.Updater(#{update}, "

  function << "'#{url_for(options[:url])}'"
  function << ", #{javascript_options})"

  function = "#{options[:before]}; #{function}" if options[:before]
  function = "#{function}; #{options[:after]}"  if options[:after]
  function = "if (#{options[:condition]}) { #{function}; }" if options[:condition]
  function = "if (confirm('#{escape_javascript(options[:confirm])}')) { #{function}; }" if options[:confirm]

  return function
end

#sortable_element(element_id, options = {}) ⇒ Object

Makes the element with the DOM ID specified by element_id sortable by drag-and-drop and make an AJAX call whenever the sort order has changed. By default, the action called gets the serialized sortable element as parameters.

This method requires the inclusion of the script.aculo.us JavaScript library.

Example:

<%= sortable_element("my_list", :url => { :action => "order" }) %>

In the example, the action gets a “my_list” array parameter containing the values of the ids of elements the sortable consists of, in the current order.

You can change the behaviour with various options, see script.aculo.us for more documentation.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 399

def sortable_element(element_id, options = {})
  options[:with]     ||= "Sortable.serialize('#{element_id}')"
  options[:onUpdate] ||= "function(){" + remote_function(options) + "}"
  options.delete_if { |key, value| AJAX_OPTIONS.include?(key) }
  
  [:tag, :overlap, :constraint, :handle].each do |option|
    options[option] = "'#{options[option]}'" if options[option]
  end
  
  options[:containment] = array_or_string_for_javascript(options[:containment]) if options[:containment]
  options[:only] = array_or_string_for_javascript(options[:only]) if options[:only]
  
  javascript_tag("Sortable.create('#{element_id}', #{options_for_javascript(options)})")
end

#submit_to_remote(name, value, options = {}) ⇒ Object

Returns a button input tag that will submit form using XMLHttpRequest in the background instead of regular reloading POST arrangement. options argument is the same as in form_remote_tag


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# File 'lib/action_view/helpers/javascript_helper.rb', line 171

def submit_to_remote(name, value, options = {})
  options[:with] ||= 'Form.serialize(this.form)'

  options[:html] ||= {}
  options[:html][:type] = 'button'
  options[:html][:onclick] = "#{remote_function(options)}; return false;"
  options[:html][:name] = name
  options[:html][:value] = value

  tag("input", options[:html], false)
end

#update_element_function(element_id, options = {}, &block) ⇒ Object

Returns a Javascript function (or expression) that'll update a DOM element according to the options passed.

  • :content: The content to use for updating. Can be left out if using block, see example.

  • :action: Valid options are :update (assumed by default), :empty, :remove

  • :position If the :action is :update, you can optionally specify one of the following positions: :before, :top, :bottom, :after.

Examples:

<%= javascript_tag(update_element_function(
      "products", :position => :bottom, :content => "<p>New product!</p>")) %>

<% replacement_function = update_element_function("products") do %>
  <p>Product 1</p>
  <p>Product 2</p>
<% end %>
<%= javascript_tag(replacement_function) %>

This method can also be used in combination with remote method call where the result is evaluated afterwards to cause multiple updates on a page. Example:

# Calling view
<%= form_remote_tag :url => { :action => "buy" }, :complete => evaluate_remote_response %>
all the inputs here...

# Controller action
def buy
  @product = Product.find(1)
end

# Returning view
<%= update_element_function(
      "cart", :action => :update, :position => :bottom, 
      :content => "<p>New Product: #{@product.name}</p>")) %>
<% update_element_function("status", :binding => binding) do %>
  You've bought a new product!
<% end %>

Notice how the second call doesn't need to be in an ERb output block since it uses a block and passes in the binding to render directly. This trick will however only work in ERb (not Builder or other template forms).


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# File 'lib/action_view/helpers/javascript_helper.rb', line 221

def update_element_function(element_id, options = {}, &block)
  
  content = escape_javascript(options[:content] || '')
  content = escape_javascript(capture(&block)) if block
  
  javascript_function = case (options[:action] || :update)
    when :update
      if options[:position]
        "new Insertion.#{options[:position].to_s.camelize}('#{element_id}','#{content}')"
      else
        "$('#{element_id}').innerHTML = '#{content}'"
      end
    
    when :empty
      "$('#{element_id}').innerHTML = ''"
    
    when :remove
      "Element.remove('#{element_id}')"
    
    else
      raise ArgumentError, "Invalid action, choose one of :update, :remove, :empty"
  end
  
  javascript_function << ";\n"
  options[:binding] ? concat(javascript_function, options[:binding]) : javascript_function
end

#visual_effect(name, element_id = false, js_options = {}) ⇒ Object

Returns a JavaScript snippet to be used on the AJAX callbacks for starting visual effects.

This method requires the inclusion of the script.aculo.us JavaScript library.

Example:

<%= link_to_remote "Reload", :update => "posts", 
      :url => { :action => "reload" }, 
      :complete => visual_effect(:highlight, "posts", :duration => 0.5 )

If no element_id is given, it assumes “element” which should be a local variable in the generated JavaScript execution context. This can be used for example with drop_receiving_element:

<%= drop_receving_element (...), :loading => visual_effect(:fade) %>

This would fade the element that was dropped on the drop receiving element.

You can change the behaviour with various options, see script.aculo.us for more documentation.


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# File 'lib/action_view/helpers/javascript_helper.rb', line 378

def visual_effect(name, element_id = false, js_options = {})
  element = element_id ? "'#{element_id}'" : "element"
  "new Effect.#{name.to_s.camelize}(#{element},#{options_for_javascript(js_options)});"
end