A mixin to allow arrow key and letter key navigation of child Elements. It can be used by delite/Container based widgets with a flat list of children, or more complex widgets like a Tree.
To use this mixin, the subclass must:
- Implement one method for each keystroke that the subclass wants to handle.
The methods for up and down arrow keys are
upKeyHandler() and
downKeyHandler(). For BIDI support, the left and right arrows are handled specially, mapped to the
previousKeyHandler()and
nextKeyHandler()methods in LTR mode, or reversed in RTL mode. Otherwise, the method name is based on the key names defined by https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/key, for example
homeKeyHandler(). The method takes two parameters: the event, and the currently navigated node. Most subclasses will want to implement either
previousKeyHandler()and
nextKeyHandler(), or
downKeyHandler()and
upKeyHandler()`. - Set all navigable descendants' initial tabIndex to "-1"; both initial descendants and any
descendants added later, by for example
addChild()
. Exception: iffocusDescendants
is false then the descendants shouldn't have any tabIndex at all. - Define
descendantSelector
as a function or string that identifies navigable child Elements. - If the descendant elements contain text, they should have a label attribute. KeyNav uses the label attribute for letter key navigation.
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Extends
Show inheritedMembers
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<protected> attached :boolean
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Set to true when
attachedCallback()
has completed, and false whendetachedCallback()
called.Type:
- boolean
- Inherited From:
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<protected> baseClass :string
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Root CSS class of the widget (ex: "d-text-box")
Type:
- string
- Inherited From:
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<protected> created :boolean
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Set to true when
createdCallback()
has completed.Type:
- boolean
- Inherited From:
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<protected, constant> descendantSelector :string|function
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Selector to identify which descendant Elements are navigable via arrow keys or keyboard search. Note that for subclasses like a Tree, one navigable node could be a descendant of another.
It's either a function that takes an Element parameter and returns true/false, or a CSS selector string, for example ".list-item".
By default, the direct DOM children of this widget are considered the selectable descendants.
Must be set in the prototype rather than on the instance.
Type:
- string | function
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dir :string
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Controls the layout direction of the widget, for example whether the arrow of a Combobox appears to the right or the left of the input field.
Values are "ltr" and "rtl", or "" which means that the value is inherited from the setting on the document root (either
<html>
or<body>
).Type:
- string
- Inherited From:
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<readonly> effectiveDir :string
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Actual direction of the widget, which can be set explicitly via
dir
property or inherited from the setting on the document root (either<html>
or<body>
). Value is either "ltr" or "rtl".Type:
- string
- Inherited From:
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<protected> focusDescendants :boolean
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When true, focus the descendant widgets as the user navigates to them via arrow keys or keyboard letter search. When false, rather than focusing the widgets, it merely sets
navigatedDescendant
, and sets thed-active-descendant
class on the descendant widget the user has navigated to.False mode is intended for widgets like ComboBox where the focus is somewhere outside this widget (typically on an
<input>
) and keystrokes are merely being forwarded to the KeyNav widget.When set to false:
- All navigable descendants must specify an id.
- Navigable descendants shouldn't have any tabIndex (as opposed to having tabIndex=-1).
- The focused element should specify
aria-owns
to point to this KeyNav Element. - The focused Element must be kept synced so that
aria-activedescendant
points to the currently navigated descendant. Do this responding to thekeynav-child-navigated
event emitted by this widget, or by callingobserve()
and monitoring changed tonavigatedDescendant
. - The focused Element must forward keystrokes by calling
emit("keydown", ...)
and/oremit("keypress", ...)
on this widget. - You must somehow set the initial navigated descendant, typically by calling
navigateToFirst()
either when the the dropdown is opened, or on the first call todownKeyHandler()
. - You must have some CSS styling so that the currently navigated node is apparent.
See http://www.w3.org/WAI/GL/wiki/Using_aria-activedescendant_to_allow_changes_in_focus_within_widgets_to_be_communicated_to_Assistive_Technology#Example_1:_Combobox for details.
Type:
- boolean
- Default Value:
- true
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<protected> focused :boolean
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This widget or a widget it contains has focus, or is "active" because it was recently clicked.
Type:
- boolean
- Inherited From:
- Default Value:
- false
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<protected, readonly> navigatedDescendant :Element
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The currently navigated descendant, or null if there isn't one.
Type:
- Element
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<protected> template :function
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Value returned by delite/handlebars! or compatible template engine. Specifies how to build the widget DOM initially and also how to update the DOM when widget properties change.
Type:
- function
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<protected, constant> widgetId :number
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Unique id for this widget, separate from id attribute (which may or may not be set). Useful when widget creates subnodes that need unique id's.
Type:
- number
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Methods
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<protected> _get(name) → {*}
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Internal helper for directly accessing an attribute value.
Directly gets the value of an attribute on an object, bypassing any accessor getter. It is designed to be used by descendant class if they want to access the value in their custom getter before returning it.
Parameters:
Name Type Description name
string Name of property.
- Inherited From:
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Returns:
Value of property.
- Type
- *
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<protected> _set(name, value)
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Internal helper for directly setting a property value without calling the custom setter.
Directly changes the value of an attribute on an object, bypassing any accessor setter. Also notifies callbacks registered via observe(). Custom setters should call
_set
to actually record the new value.Parameters:
Name Type Description name
string The property to set.
value
* Value to set the property to.
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attachedCallback()
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Called automatically when the element is added to the document, after
createdCallback()
completes. This method is automatically chained, so subclasses generally do not need to usedcl.superCall()
,dcl.advise()
, etc.- Inherited From:
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Fires:
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computeProperties(oldValues, isAfterCreation)
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Callback function to calculate computed properties upon property changes.
Parameters:
Name Type Description oldValues
Object The hash table of old property values, keyed by property names.
isAfterCreation
boolean True if this call is right after instantiation.
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<protected> createdCallback()
-
Called when the custom element is created, or when
register.parse()
parses a custom tag.This method is automatically chained, so subclasses generally do not need to use
dcl.superCall()
,dcl.advise()
, etc.- Inherited From:
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<protected> defer(fcn, delay) → {Object}
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Wrapper to setTimeout to avoid deferred functions executing after the originating widget has been destroyed.
Parameters:
Name Type Description fcn
function Function to be executed after specified delay (or 0ms if no delay specified).
delay
number Delay in ms, defaults to 0.
- Inherited From:
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Returns:
Handle with a remove method that deschedules the callback from being called.
- Type
- Object
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deliver()
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Synchronously deliver change records to all listeners registered via
observe()
.- Inherited From:
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deliverComputing()
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Synchronously deliver change records for computed properties so that
computeProperties()
is called if there are pending change records.- Inherited From:
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destroy()
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Release resources used by this custom element and its descendants. After calling this method, the element can no longer be used, and should be removed from the document.
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detachedCallback()
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Called when the element is removed the document. This method is automatically chained, so subclasses generally do not need to use
dcl.superCall()
,dcl.advise()
, etc.- Inherited From:
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discardChanges()
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Discard change records for all listeners registered via
observe()
.- Inherited From:
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discardComputing()
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Discard change records for computed properties.
- Inherited From:
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<protected> emit(type, eventObj) → {boolean}
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Emits a synthetic event of specified type, based on eventObj.
Parameters:
Name Type Argument Description type
string Name of event.
eventObj
Object <optional>
Properties to mix in to emitted event. Can also contain
bubbles
andcancelable
properties to control how the event is emitted.- Inherited From:
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Returns:
True if the event was not canceled, false if it was canceled.
- Type
- boolean
Example
myWidget.emit("query-success", {});
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<protected> endKeyHandler(evt, navigatedDescendant)
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Called on end key.
Parameters:
Name Type Description evt
Event navigatedDescendant
Element - Source:
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findCustomElements(root)
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Search subtree under root returning custom elements found.
Parameters:
Name Type Argument Description root
Element <optional>
Node to search under.
- Inherited From:
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focus()
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/** Default focus() implementation: navigate to the first navigable descendant. Note that if
focusDescendants
is false, this will merely set thed-active-descendant
class rather than actually focusing the descendant.- Source:
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getEnclosingWidget(node)
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Returns the widget whose DOM tree contains the specified DOMNode, or null if the node is not contained within the DOM tree of any widget
Parameters:
Name Type Description node
Element - Inherited From:
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<protected> getInheritedDir() → {string}
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Get the direction setting for the page itself.
- Inherited From:
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Returns:
"ltr" or "rtl"
- Type
- string
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<protected> getNext(child, dir) → {Element}
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Returns the next or previous navigable descendant, relative to "child". If "child" is this, then it returns the first focusable descendant (when dir === 1) or last focusable descendant (when dir === -1).
Parameters:
Name Type Description child
Element The current child Element.
dir
number 1 = after, -1 = before
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Returns:
- Type
- Element
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getParent()
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Returns the parent widget of this widget, or null if there is no parent widget.
- Inherited From:
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<protected> getProps() → {Object}
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Returns a hash of properties that should be observed.
- Inherited From:
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Returns:
Hash of properties.
- Type
- Object
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<protected> getPropsToObserve() → {Array.<string>}
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Get list of properties that Stateful#observe() should observe.
- Inherited From:
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Returns:
list of properties
- Type
- Array.<string>
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<protected> homeKeyHandler(evt, navigatedDescendant)
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Called on home key.
Parameters:
Name Type Description evt
Event navigatedDescendant
Element - Source:
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<protected> initializeInvalidating()
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Make initial calls to
computeProperties()
,initializeRendering()
, andrefreshRendering()
, and setup observers so those methods are called whenever properties are modified in the future. Normally this method is called automatically by the constructor, and should not be called manually, but the method is exposed for custom elements since they do not call theconstructor()
method.- Inherited From:
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initializeRendering(oldValues)
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Callback function to initialize rendering.
Parameters:
Name Type Description oldValues
Object The hash table of old property values, keyed by property names.
- Inherited From:
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<protected> introspect(props)
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Sets up ES5 getters/setters for each class property. Inside introspect(), "this" is a reference to the prototype rather than any individual instance.
Parameters:
Name Type Description props
Object Hash of properties.
- Inherited From:
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mix(hash)
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Set a hash of properties on a Stateful instance.
Parameters:
Name Type Description hash
Object Hash of properties.
- Inherited From:
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Example
myObj.mix({ foo: "Howdy", bar: 3 });
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<protected> navigateTo(child, last, triggerEvent)
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Navigate to the specified descendant. Note that if
focusDescendants
is false, this will merely set thed-active-descendant
class rather than actually focusing the descendant.Parameters:
Name Type Argument Description child
Element Reference to the descendant.
last
boolean <optional>
If true and if descendant has multiple focusable nodes, focus the last one instead of the first one. This assumes that the child's
focus()
method takes a boolean parameter wheretrue
means to focus the last child.triggerEvent
Event <optional>
The event that lead to the navigation, or
undefined
if the navigation is triggered programmatically.- Source:
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<protected> navigateToFirst(triggerEvent)
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Navigate to the first navigable descendant. Note that if
focusDescendants
is false, this will merely set thed-active-descendant
class rather than actually focusing the descendant.Parameters:
Name Type Argument Description triggerEvent
Event <optional>
The event that lead to the navigation, or
undefined
if the navigation is triggered programmatically.- Source:
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<protected> navigateToLast(triggerEvent)
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Navigate to the last navigable descendant. Note that if
focusDescendants
is false, this will merely set thed-active-descendant
class rather than actually focusing the descendant.Parameters:
Name Type Argument Description triggerEvent
Event <optional>
The event that lead to the navigation, or
undefined
if the navigation is triggered programmatically.- Source:
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notifyCurrentValue(name)
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Notifies current values to observers for specified property name(s). Handy to manually schedule invocation of observer callbacks when there is no change in value.
Parameters:
Name Type Argument Description name
string <repeatable>
The property name.
- Inherited From:
- Source:
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observe(callback) → {module:decor/Stateful.PropertyListObserver}
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Observes for change in properties. Callback is called at the end of micro-task of changes with a hash table of old values keyed by changed property. Multiple changes to a property in a micro-task are squashed.
Parameters:
Name Type Description callback
function The callback.
- Inherited From:
- Source:
Returns:
The observer that can be used to stop observation or synchronously deliver/discard pending change records.
Example
var stateful = new (dcl(Stateful, { foo: undefined, bar: undefined, baz: undefined }))({ foo: 3, bar: 5, baz: 7 }); stateful.observe(function (oldValues) { // oldValues is {foo: 3, bar: 5, baz: 7} }); stateful.foo = 4; stateful.bar = 6; stateful.baz = 8; stateful.foo = 6; stateful.bar = 8; stateful.baz = 10;
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on(type, func, node) → {Object}
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Call specified function when event occurs.
Note that the function is not run in any particular scope, so if (for example) you want it to run in the element's scope you must do
myCustomElement.on("click", myCustomElement.func.bind(myCustomElement))
.Note that
delite/Widget
overrideson()
so thaton("focus", ...)
and `on("blur", ...) will trigger the listener when focus moves into or out of the widget, rather than just when the widget's root node is focused/blurred. In other words, the listener is called when the widget is conceptually focused or blurred.Parameters:
Name Type Argument Description type
string Name of event (ex: "click").
func
function Callback function.
node
Element <optional>
Element to attach handler to, defaults to
this
.- Inherited From:
- Source:
Returns:
Handle with
remove()
method to cancel the event.- Type
- Object
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<protected> own() → {Array.<Object>}
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Track specified handles and remove/destroy them when this instance is destroyed, unless they were already removed/destroyed manually.
- Inherited From:
- Source:
Returns:
The array of specified handles, so you can do for example:
var handle = this.own(on(...))[0];
- Type
- Array.<Object>
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<protected> parseAttribute(name, value)
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Helper for parsing declarative widgets. Interpret a given attribute specified in markup, returning either:
undefined
: ignore{prop: prop, value: value}
: setthis[prop] = value
{event: event, callback: callback}
: callthis.on(event, callback)
Parameters:
Name Type Description name
string Attribute name.
value
string Attribute value.
- Inherited From:
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<protected> parseFunctionAttribute(value, params)
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Helper to parse function attribute in markup. Unlike
_parsePrototypeAttr()
, does not require a corresponding widget property. Functions can be specified as global variables or as inline javascript:Parameters:
Name Type Description value
string Value of the attribute.
params
Array.<string> When generating a function from inline javascript, give it these parameter names.
- Inherited From:
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<protected> placeAt(reference, position) → {module:delite/Widget}
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Place this widget somewhere in the dom, and allow chaining.
Parameters:
Name Type Argument Description reference
string | Element | DocumentFragment Element, DocumentFragment, or id of Element to place this widget relative to.
position
string | number <optional>
Numeric index or a string with the values:
- number - place this widget as n'th child of
reference
node - "first" - place this widget as first child of
reference
node - "last" - place this widget as last child of
reference
node - "before" - place this widget as previous sibling of
reference
node - "after" - place this widget as next sibling of
reference
node - "replace" - replace specified reference node with this widget
- "only" - replace all children of
reference
node with this widget
- Inherited From:
- Source:
Returns:
This widget, for chaining.
- Type
- module:delite/Widget
Examples
// create a Button with no srcNodeRef, and place it in the body: var button = new Button({ label:"click" }).placeAt(document.body);
// place a new button as the first element of some div var button = new Button({ label:"click" }).placeAt("wrapper","first");
// create a contentpane and add it to a TabContainer var tc = document.getElementById("myTabs"); new ContentPane({ href:"foo.html", title:"Wow!" }).placeAt(tc)
- number - place this widget as n'th child of
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<protected> postRender()
-
Processing after the DOM fragment is created.
Called after the DOM fragment has been created, but not necessarily added to the document. Do not include any operations which rely on node dimensions or placement.
This method is automatically chained, so subclasses generally do not need to use
dcl.superCall()
,dcl.advise()
, etc.- Inherited From:
- Source:
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<protected> preRender()
-
Processing before
render()
.This method is automatically chained, so subclasses generally do not need to use
dcl.superCall()
,dcl.advise()
, etc.- Inherited From:
- Source:
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<protected> processConstructorParameters()
-
Called after Object is created to process parameters passed to constructor.
- Inherited From:
- Source:
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refreshRendering(oldValues, isAfterInitialRendering)
-
Callback function to render UI upon property changes.
Parameters:
Name Type Description oldValues
Object The hash table of old property values, keyed by property names.
isAfterInitialRendering
boolean True if this call is right after
initializeRendering()
.- Inherited From:
- Source:
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<protected> render()
-
Construct the UI for this widget, filling in subnodes and/or text inside of this. Most widgets will leverage delite/handlebars! to set
template
, rather than defining this method.- Inherited From:
- Source:
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<protected> setClassComponent(component, value, node)
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Helper method to set a class (or classes) on a given node, removing the class (or classes) set by the previous call to
setClassComponent()
for the specified component and node. Used mainly by template.js to set classes without overwriting classes set by the user or other code (ex: CssState).Parameters:
Name Type Argument Description component
string Specifies the category.
value
string Class (or classes) to set.
node
HTMLElement <optional>
The node to set the property on; defaults to widget root node.
- Inherited From:
- Source:
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<protected> setOrRemoveAttribute(node, name, value)
-
Helper method to set/remove an attribute based on the given value:
- If value is undefined, the attribute is removed. Useful for attributes like aria-valuenow.
- If value is boolean, the attribute is set to "true" or "false". Useful for attributes like aria-selected.
- If value is a number, it's converted to a string.
Parameters:
Name Type Description node
Element The node to set the property on.
name
string Name of the property.
value
string Value of the property.
- Inherited From:
- Source:
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shouldInitializeRendering(oldValues, isAfterCreation) → {boolean}
-
Function to return if rendering should be initialized. (Instead of making partial changes for post-initialization)
Parameters:
Name Type Description oldValues
Object The hash table of old property values, keyed by property names.
isAfterCreation
boolean True if this call is right after instantiation.
- Inherited From:
- Source:
Returns:
True if rendering should be initialized.
- Type
- boolean
Events
-
customelement-attached
-
Dispatched after the CustomElement has been attached. This is useful to be notified when an HTMLElement has been upgraded to a CustomElement and attached to the DOM, in particular on browsers supporting native Custom Element.
- Inherited From:
- Source:
Example
element.addEventListener("customelement-attached", function (evt) { console.log("custom element: "+evt.target.id+" has been attached"); });
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keynav-child-navigated
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Dispatched after the user has selected a different descendant, by clicking, arrow keys, or keyboard search.
- Source:
Properties:
Name Type Description oldValue
number The previously selected item.
newValue
number The new selected item.
Example
widget.on("keynav-child-navigated", function (evt) { console.log("old value: " + evt.oldValue); console.log("new value: " + evt.newValue); }