Jump To …


Copyright 2012-2013 The Apache Software Foundation

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at


Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.


This is the abstraction layer that allows the majority of components to operate without caring whether the underlying infrastructure framework is Prototype, jQuery, or something else.

The abstraction layer has a number of disadvantages:

  • It adds a number of layers of wrapper around the infrastructure framework objects
  • It is leaky; some behaviors will vary slightly based on the active infrastructure framework
  • The abstraction is alien to both Prototype and jQuery developers; it mixes some ideas from both
  • It is much less powerful or expressive than either infrastructure framework used directly

It is quite concievable that some components will require direct access to the infrastructure framework, especially those that are wrappers around third party libraries or plugins; however many simple components may need no more than the abstract layer and gain the valuable benefit of not caring about the infrastructure framework.

define ["underscore", "./utils", "./events", "jquery"],
(_, utils, events, $) ->

Converts content (provided to ElementWrapper.update() or append()) into an appropriate type. This primarily exists to validate the value, and to "unpack" an ElementWrapper into a DOM element.

  convertContent = (content) ->
    if _.isString content
      return content

    if _.isElement content
      return content

    if content instanceof ElementWrapper
      return content.$

    throw new Error "Provided value <#{content}> is not valid as DOM element content."

Generic view of an DOM event that is passed to a handler function.


  • nativeEvent - the native Event object, which may provide additional information.
  • memo - the object passed to ElementWrapper.trigger().
  • type - the name of the event that was triggered.
  • char - the character value of the pressed key, if a printable character, as a string.
  • key -The key value of the pressed key. This is the same as the char property for printable keys, or a key name for others.
  class EventWrapper

    constructor: (event, memo) ->
      @nativeEvent = event
      @memo = memo

This is to satisfy YUICompressor which doesn't seem to like 'char', even though it doesn't appear to be a reserved word.

      this[name] = event[name] for name in ["type", "char", "key"]

Stops the event which prevents further propagation of the DOM event, as well as DOM event bubbling.

    stop: ->

Interface between the dom's event model, and jQuery's.

  • jqueryObject - jQuery wrapper around one or more DOM elements
  • eventNames - space-separated list of event names
  • match - selector to match bubbled elements, or null
  • handler - event handler function to invoke; it will be passed an EventWrapper instance as the first parameter, and the memo as the second parameter. this will be the ElementWrapper for the matched element.

Event handlers may return false to stop event propogation; this prevents an event from bubbling up, and prevents any browser default behavior from triggering. This is often easier than accepting the EventWrapper object as the first parameter and invoking stop().

  onevent = (jqueryObject, eventNames, match, handler) ->
    throw new Error "No event handler was provided." unless handler?

    wrapped = (jqueryEvent, memo) ->

Set this to be the matched ElementWrapper, rather than the element on which the event is observed (which is often further up the hierarchy).

      elementWrapper = new ElementWrapper $(jqueryEvent.target)
      eventWrapper = new EventWrapper jqueryEvent, memo

      result = handler.call elementWrapper, eventWrapper, memo

If an event handler returns exactly false, then stop the event.

      if result is false


    jqueryObject.on eventNames, match, wrapped


Wraps a DOM element, providing some common behaviors. Exposes the DOM element as property element.

  class ElementWrapper

Passed the jQuery object

    constructor: (query) ->
      @$ = query
      @element = query[0]

Some coders would use some JavaScript cleverness to automate more of the mapping from the ElementWrapper API to the jQuery API, but that eliminates a chance to write some very necessary documentation.

    toString: ->
      markup = @element.outerHTML

      "ElementWrapper[#{markup.substring 0, (markup.indexOf ">") + 1}]"

Hides the wrapped element, setting its display to 'none'.

    hide: ->

      return this

Displays the wrapped element if hidden.

    show: ->

      return this

Gets or sets a CSS property. jQuery provides a lot of mapping of names to canonical names.

    css: (name, value) ->

      if arguments.length is 1
        return @$.css name

      @$.css name, value

      return this

Returns the offset of the object relative to the document. The returned object has keys top' and left'.

    offset: ->

Removes the wrapped element from the DOM. It can later be re-attached.

    remove: ->

      return this

Reads or updates an attribute. With one argument, returns the current value of the attribute. With two arguments, updates the attribute's value, and returns the previous value. Setting an attribute to null is the same as removing it.

Alternately, the first attribute can be an object in which case all the keys and values of the object are applied as attributes, and this ElementWrapper is returned.

  • name - the attribute to read or update, or an object of keys and values
  • value - (optional) the new value for the attribute
    attr: (name, value) ->

      if _.isObject name
        for attributeName, value of name
          @attr attributeName, value

        return this

      current = @$.attr name
      if arguments.length > 1
        if value is null
          @$.removeAttr name
          @$.attr name, value
      if _.isUndefined current
        current = null

      return current

Moves the cursor to the field.

    focus: ->

      return this

Returns true if the element has the indicated class name, false otherwise.

    hasClass: (name) ->
      @$.hasClass name

Removes the class name from the element.

    removeClass: (name) ->
      @$.removeClass name

      return this

Adds the class name to the element.

    addClass: (name) ->
      @$.addClass name

      return this

Updates this element with new content, replacing any old content. The new content may be HTML text, or a DOM element, or an ElementWrapper, or null (to remove the body of the element).

    update: (content) ->

      if content
        @$.append (convertContent content)

      return this

Appends new content (Element, ElementWrapper, or HTML markup string) to the body of the element.

    append: (content) ->
      @$.append (convertContent content)

      return this

Prepends new content (Element, ElementWrapper, or HTML markup string) to the body of the element.

    prepend: (content) ->
      @$.prepend (convertContent content)

      return this

Inserts new content (Element, ElementWrapper, or HTML markup string) into the DOM immediately before this ElementWrapper's element.

    insertBefore: (content) ->
      @$.before (convertContent content)

      return this

Inserts new content (Element, ElementWrapper, or HTML markup string) into the DOM immediately after this ElementWrapper's element.

    insertAfter: (content) ->
      @$.after (convertContent content)

      return this

Finds the first child element that matches the CSS selector, wrapped as an ElementWrapper. Returns null if not found.

    findFirst: (selector) ->
      match = @$.find selector

      if match.length

At least one element was matched, just keep the first

        new ElementWrapper match.first()
        return null

Finds all child elements matching the CSS selector, returning them as an array of ElementWrappers.

    find: (selector) ->
      matches = @$.find selector

      for i in [0...matches.length]
        new ElementWrapper matches.eq i

Find the first container element that matches the selector (wrapped as an ElementWrapper), or returns null.

    findParent: (selector) ->
      parents = @$.parents selector

      return null unless parents.length

      new ElementWrapper parents.eq(0)

Returns this ElementWrapper if it matches the selector; otherwise, returns the first container element (as an ElementWrapper) that matches the selector. Returns null if no container element matches.

    closest: (selector) ->
      match = @$.closest selector

        when match.length is 0 then return null
        when match[0] is @element then return this
        else return new ElementWrapper match

Returns an ElementWrapper for this element's containing element. Returns null if this element has no parent (either because this element is the document object, or because this element is not yet attached to the DOM).

    parent: ->
      parent = @$.parent()

      return null unless parent.length
      new ElementWrapper parent

Returns an array of all the immediate child elements of this element, as ElementWrappers.

    children: ->
      children = @$.children()

      for i in [0...children.length]
        new ElementWrapper children.eq i

Returns true if this element is visible, false otherwise. This does not check to see if all containers of the element are visible.

    visible: ->
      @$.css("display") isnt "none"

Returns true if this element is visible, and all parent elements are also visible, up to the document body.

    deepVisible: ->
      cursor = this
      while cursor
        return false unless cursor.visible()
        cursor = cursor.parent()

        return true if cursor and cursor.element is document.body

Bound not reached, meaning that the Element is not currently attached to the DOM.

      return false

Fires a named event, passing an optional memo object to event handler functions. This must support common native events (exact list TBD), as well as custom events (in Prototype, custom events must have a prefix that ends with a colon).

  • eventName - name of event to trigger on the wrapped Element
  • memo - optional value assocated with the event; available as WrappedeEvent.memo in event handler functions (must be null for native events). The memo, when provided, should be an object; it is an error if it is a string or other non-object type..

Returns true if the event fully executed, or false if the event was canceled.

    trigger: (eventName, memo) ->
      throw new Error "Attempt to trigger event with null event name" unless eventName?

      unless (_.isNull memo) or (_.isObject memo) or (_.isUndefined memo)
        throw new Error "Event memo may be null or an object, but not a simple type."

      jqEvent = $.Event eventName

      @$.trigger jqEvent, memo

      return not jqEvent.isImmediatePropagationStopped()

With no parameters, returns the current value of the element (which must be a form control element, such as <input> or <textarea>). With one parameter, updates the field's value, and returns the previous value. The underlying foundation is responsible for mapping this correctly based on the type of control element. TODO: Define behavior for multi-named elements, such as <select>.

  • newValue - (optional) new value for field
    value: (newValue) ->
      current = @$.val()

      if arguments.length > 0
        @$.val newValue
      return current

Returns true if element is a checkbox and is checked

    checked: ->

Stores or retrieves meta-data on the element. With one parameter, the current value for the name is returned (or undefined). With two parameters, the meta-data is updated and the previous value returned. For Prototype, the meta data is essentially empty (except, perhaps, for some internal keys used to store event handling information). For jQuery, the meta data may be initialized from data- attributes.

  • name - name of meta-data value to store or retrieve
  • value - (optional) new value for meta-data
    meta: (name, value) ->
      current = @$.data name

      if arguments.length > 1
        @$.data name, value
      return current

Adds an event handler for one or more events.

  • events - one or more event names, separated by spaces
  • match - optional: CSS expression used as a filter; only events that bubble up to the wrapped element from an originating element that matches the CSS expression will invoke the handler.
  • handler - function invoked; the function is passed an EventWrapper object, and the context (this) is the ElementWrapper for the matched element.
    on: (events, match, handler) ->
      exports.on @element, events, match, handler
      return this

Returns the text of the element (and its children).

    text: ->

Wrapper around the jqXHR object

  class RequestWrapper

    constructor: (@jqxhr) ->

Abort a running ajax request

    abort: -> @jqxhr.abort()

Wrapper around the jqXHR object

  class ResponseWrapper

    constructor: (@jqxhr, data) ->

      @status = jqxhr.status
      @statusText = jqxhr.statusText
      @json = data # Mostly right?  Need a content type check?
      @text = jqxhr.responseText

Retrieves a response header by name

    header: (name) ->
      @jqxhr.getResponseHeader name

Used to track how many active Ajax requests are currently in-process. This is incremented when an Ajax request is started, and decremented when an Ajax request completes or fails. The body attribute data-ajax-active is set to "true" or "false" whenever the count changes. This only applies to Ajax requests that are filtered through the t5/core/dom API; other libraries (including RequireJS) which bypass this API are not counted.

  activeAjaxCount = 0

  adjustAjaxCount = (delta) ->
    activeAjaxCount += delta

    exports.body.attr "data-ajax-active", (activeAjaxCount > 0)

Performs an asynchronous Ajax request, invoking callbacks when it completes.

This is very low level; most code will want to go through the t5/core/ajax module instead, which adds better handling of exceptions and failures, and handles Tapestry's partial page render reponse keys.

  • options.method - "post", "get", etc., default: "post".
  • options.contentType - request content, defaults to "application/x-www-form-urlencoded"
  • options.data - optional, additional key/value pairs (for the default content type)
  • options.success - handler to invoke on success. Passed the ResponseWrapper object. Default does nothing.
  • options.failure - handler to invoke on failure (server responds with a non-2xx code). Passed the response. Default will throw the exception
  • options.exception - handler to invoke when an exception occurs (often means the server is unavailable). Passed the exception. Default will generate an exception message and throw an Error. Note: not really supported under jQuery, a hold-over from Prototype. Returns the module's exports
  ajaxRequest = (url, options = {}) ->
    jqxhr = $.ajax
      url: url
      type: options.method?.toUpperCase() or "POST"
      contentType: options.contentType
      traditional: true
      data: options.data

jQuery doesn't have the equivalent of Protoype's onException

      error: (jqXHR, textStatus, errorThrown) ->
        adjustAjaxCount -1

        return if textStatus is "abort"
        message = "Request to #{url} failed with status #{textStatus}"
        text = jqXHR.statusText
        if not _.isEmpty text
          message += " -- #{text}"
        message += "."

        if options.failure
          options.failure (new ResponseWrapper jqXHR), message
          throw new Error message


      success: (data, textStatus, jqXHR) ->

        adjustAjaxCount -1

        options.success and options.success(new ResponseWrapper jqXHR, data)

    adjustAjaxCount +1

    new RequestWrapper jqxhr

  scanners = null

Sets up a scanner callback; this is used to perfom one-time setup of elements that match a particular CSS selector. The callback is passed each element that matches the selector. The callback is expected to modify the element so that it does not match future selections caused by zone updates, typically by removing the CSS class or data- attribute referenced by the selector.

  scanner = (selector, callback) ->

Define a function that scans some root element (the body initially; later an updated Zone)

    scan = (root) ->
      callback el for el in root.find selector

Do it once immediately:

    scan exports.body

Lazily set up a single event handler for running any added scanners.

    if scanners is null
      scanners = []
      exports.body.on events.zone.didUpdate, ->
        f this for f in scanners

    scanners.push scan


The main export is a function that wraps a DOM element as an ElementWrapper; additional functions are attached as properties.

  • element - a DOM element, or a string id of a DOM element

Returns the ElementWrapper, or null if no element with the id exists

  exports = wrapElement = (element) ->
    if _.isString element
      element = document.getElementById element
      return null unless element
      throw new Error "Attempt to wrap a null DOM element" unless element

Assume the object is a DOM element, document or window; something that is compatible with the jQuery API (especially with respect to events).

    new ElementWrapper ($ element)

Creates a new element, detached from the DOM.

  • elementName - (string) name of element to create, if ommitted, then "div"
  • attributes - (object) attributes to apply to the created element (may be omitted)
  • body - (string) content for the new element, may be omitted for no body
  createElement = (elementName, attributes, body) ->

    if _.isObject elementName
      body = attributes
      attributes = elementName
      elementName = null

    if _.isString attributes
      body = attributes
      attributes = null

    element = wrapElement document.createElement (elementName or "div")

    if attributes
      element.attr attributes

    if body
      element.update body

    return element

  _.extend exports,
    wrap: wrapElement

    create: createElement

    ajaxRequest: ajaxRequest

Used to add an event handler to an element (possibly from elements below it in the hierarch).

  • selector - CSS selector used to select elements to attach handler to; alternately, a single DOM element, or an array of DOM elements. The document is considered an element for these purposes.
  • events - one or more event names, separated by spaces
  • match - optional: CSS expression used as a filter; only events that bubble
  • up to a selected element from an originating element that matches the CSS expression will invoke the handler.
  • handler - function invoked; the function is passed an EventWrapper object, and the context (this) is the ElementWrapper for the matched element
    on: (selector, events, match, handler) ->
      unless handler?
        handler = match
        match = null

      elements = $ selector
      onevent elements, events, match, handler

onDocument() is used to add an event handler to the document object; this is used for global (or default) handlers.

    onDocument: (events, match, handler) ->
      exports.on document, events, match, handler

Returns a wrapped version of the document.body element. Because all Tapestry JavaScript occurs inside a block at the end of the document, inside the <body> element, it is assumed that it is always safe to get the body.

    body: wrapElement document.body

    scanner: scanner

  return exports