t5-core-dom-prototype.coffee

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t5-core-dom-prototype.coffee
¶

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
```
http:#www.apache.org/licenses/LICENSE-2.0
```
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.
¶

t5/core/dom

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) ->
```
¶

Save a local reference to Prototype.$ … see notes about some challenges using Prototype, jQuery, and RequireJS together, here: https://github.com/jrburke/requirejs/issues/534
```
  $ = window.$
```
¶

Fires a native event; something that Prototype does not normally do. Returns true if the event completed normally, false if it was canceled.
```
  fireNativeEvent = (element, eventName) ->
    if document.createEventObject
```

IE support:

      event = document.createEventObject()
      return element.fireEvent "on#{eventName}", event

Everyone else:

    event = document.createEvent "HTMLEvents"
    event.initEvent eventName, true, true
    element.dispatchEvent event
    return not event.defaultPrevented

converts a selector to an array of DOM elements

  parseSelectorToElements = (selector) ->
    if _.isString selector
      return $$ selector

Array is assumed to be array of DOM elements

    if _.isArray selector
      return selector

¶

Assume its a single DOM element
```
    [selector]
```

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.element

    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.

Properties:
- 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) ->
      @nativeEvent = event
      @memo = event.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: ->
```
¶

There’s no equivalent to stopImmediatePropagation() unfortunately.
```
      @nativeEvent.stop()
```
¶

Interface between the dom’s event model, and Prototype’s.
- elements - array of DOM elements (or the document object)
- eventNames - array 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 propagation; 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().

Returns a function of no parameters that removes any added handlers.
```
  onevent = (elements, eventNames, match, handler) ->
      throw new Error "No event handler was provided." unless handler?

      wrapped = (prototypeEvent) ->
```
¶

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 prototypeEvent.findElement()
        eventWrapper = new EventWrapper prototypeEvent
```

Because there’s no stopImmediatePropogation() as with jQuery, we detect if the event was stopped and simply stop calling the handler.

        result = if prototypeEvent.stopped
                  false
                else handler.call elementWrapper, eventWrapper, eventWrapper.memo

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

        if result is false
          prototypeEvent.stop()

        return

      eventHandlers = []

      for element in elements
        for eventName in eventNames
          eventHandlers.push (Event.on element, eventName, match, wrapped)

Return a function to remove the handler(s)

      ->
        for eventHandler in eventHandlers
          eventHandler.stop()

¶

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

    constructor: (@element) ->
```
¶

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: ->
      @element.hide()

      return this

Displays the wrapped element if hidden.

    show: ->
      @element.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 @element.getStyle name

      @element.setStyle name: value

      return this

¶

Returns the offset of the object relative to the document. The returned object has keys top‘ and left‘.
```
    offset: ->
      @element.viewportOffset()
```

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

    remove: ->
      @element.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 = @element.readAttribute name
      if arguments.length > 1
```
¶

Treat undefined and null the same; Prototype does something slightly odd, treating undefined as a special case where the attribute value matches the attribute name.
```
        @element.writeAttribute name, if value is undefined then null else value

      return current
```

Moves the cursor to the field.

    focus: ->
      @element.focus()

      return this

¶

Returns true if the element has the indicated class name, false otherwise.
```
    hasClass: (name) ->
      @element.hasClassName name
```

Removes the class name from the element.

    removeClass: (name) ->
      @element.removeClassName name

      return this

Adds the class name to the element.

    addClass: (name) ->
      @element.addClassName 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) ->
      @element.update (content and convertContent content)

      return this
```

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

    append: (content) ->
      @element.insert bottom: (convertContent content)

      return this

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

    prepend: (content) ->
      @element.insert top: (convertContent content)

      return this

¶

Inserts new content (Element, ElementWrapper, or HTML markup string) into the DOM immediately before this ElementWrapper’s element.
```
    insertBefore: (content) ->
      @element.insert 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) ->
      @element.insert 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 = @element.down selector
```

Prototype returns undefined if not found, we want to return null.

      if match
        new ElementWrapper match
      else
        return null

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

    find: (selector) ->
      matches = @element.select selector

      new ElementWrapper(e) for e in matches

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

    findParent: (selector) ->
      parent = @element.up selector

      return null unless parent

      new ElementWrapper parent

¶

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) ->
      if @element.match selector
        return this

      return @findParent selector
```
¶

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 = @element.parentNode

      return null unless parent
      new ElementWrapper parent
```

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

    children: ->
      new ElementWrapper(e) for e in @element.childElements()

¶

Returns true if this element is visible, false otherwise. This does not check to see if all containers of the element are visible.
```
    visible: ->
      @element.visible()
```

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

    deepVisible: ->
      element = this.element
      element.offsetWidth > 0 && element.offsetHeight > 0

¶

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."

      if (eventName.indexOf ':') > 0
```

Custom event is supported directly by Prototype:

        event = @element.fire eventName, memo
        return not event.defaultPrevented

Native events take some extra work:

      if memo
        throw new Error "Memo must be null when triggering a native event"

Hacky solution for TAP5-2602 (5.4 LinkSubmit does not work with Prototype JS)

      unless Prototype.Browser.WebKit and eventName == 'submit' and @element instanceof HTMLFormElement
        fireNativeEvent @element, eventName
      else
        @element.requestSubmit()

¶

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 = @element.getValue()

      if arguments.length > 0
        @element.setValue newValue
      return current
```
¶

Returns true if element is a checkbox and is checked
```
    checked: ->
      @element.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 = @element.retrieve name

      if arguments.length > 1
        @element.store 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.
Returns a function of no parameters that removes any added handlers.
```
    on: (events, match, handler) ->
      exports.on @element, events, match, handler
      return this
```

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

    text: ->
      @element.textContent or @element.innerText

Wrapper around the Prototype Ajax.Request object

  class RequestWrapper

    constructor: (@req) ->

Abort a running ajax request

    abort: -> throw "Cannot abort Ajax request when using Prototype."

Wrapper around the Prototype Ajax.Response object

  class ResponseWrapper

    constructor: (@res) ->

      @status = @res.status
      @statusText = @res.statusText
      @json = @res.responseJSON
      @text = @res.responseText

Retrieves a response header by name

    header: (name) ->
      @res.getHeader 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 the number of active Ajax requests, 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
```

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 = {}) ->
    finalOptions =
      method: options.method or "post"
      contentType: options.contentType or "application/x-www-form-urlencoded"
      parameters: options.data
      onException: (ajaxRequest, exception) ->

        adjustAjaxCount -1

        if options.exception
          options.exception exception
        else
          throw exception

        return

      onFailure: (response) ->
        adjustAjaxCount -1

        message = "Request to #{url} failed with status #{response.getStatus()}"
        text = response.getStatusText()
        if not _.isEmpty text
          message += " -- #{text}"
        message += "."

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

        return

      onSuccess: (response) ->

        adjustAjaxCount -1

Prototype treats status == 0 as success, even though it may indicate that the server didn’t respond.

        if (not response.getStatus()) or (not response.request.success())
          finalOptions.onFailure(new ResponseWrapper response)
          return

Tapestry 5.3 includes lots more exception catching … that just got in the way of identifying the source of problems. That’s been stripped out.

        options.success and options.success(new ResponseWrapper response)
        return

    adjustAjaxCount +1

    new RequestWrapper (new Ajax.Request url, finalOptions)

  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
      return

¶

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.initializeComponents, ->
        f this for f in scanners
        return

    scanners.push scan

    return

¶

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 = $ element
      return null unless element
    else
      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 Prototype 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

Returns the value of a given data attribute as an object. The “data-“ prefix is added automatically. element - (object) HTML dom element attribute - (string) name of the data attribute without the “data-“ prefix.

  getDataAttributeAsObject = (element, attribute) ->

    value = $(element).readAttribute('data-' + attribute)
    if value isnt null
      value = JSON.parse(value)
    else
      value = {}

Returns the URL of a component event based on its name and an optional element or null if the event information is not found. When the element isn’t passed or it’s null, the event data is taken from the element.

eventName - (string) name of the component event
element - (object) HTML DOM element to be used as the beginning of the event data search. Optional.

  getEventUrl = (eventName, element) ->

    if not (eventName?)
      throw 'dom.getEventUrl: the eventName parameter cannot be null'

    if not _.isString eventName
      throw 'dom.getEventUrl: the eventName parameter should be a string'

    eventName = eventName.toLowerCase()

    if element is null
      element = document.body
    else if element instanceof ElementWrapper
      element = element.element;
    else if element.jquery?
      element = element[0];

Look for event data in itself first, then in the preceding siblings if not found

    url = null

    while not url? and element.previousElementSibling?
      data = getDataAttributeAsObject(element, 'component-events')
      url = data?[eventName]?.url
      element = element.previousElementSibling

    if not url?

Look at parent elements recursively

      while not url? and element.parentElement?
        data = getDataAttributeAsObject(element, 'component-events')
        url = data?[eventName]?.url
        element = element.parentElement;
    
    return url;

  _.extend exports,
  
    getEventUrl: getEventUrl
    
    wrap: wrapElement

    create: createElement

    ajaxRequest: ajaxRequest

¶

Used to add an event handler to an element (possibly from elements below it in the hierarchy).
- 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
Returns a function of no parameters that removes any added handlers.
```
    on: (selector, events, match, handler) ->
      unless handler?
        handler = match
        match = null

      elements = parseSelectorToElements selector
      events = utils.split events
      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. Returns a function of no parameters that removes any added 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
```

t5-core-dom-prototype.coffee

t5/core/dom