Mixin: module:delite/KeyNav

module:delite/KeyNav

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 _onLeftArrow(), _onRightArrow()``_onDownArrow(), _onUpArrow() methods to handle left/right/up/down keystrokes.
  • Set all navigable descendants' initial tabIndex to "-1"; both initial descendants and any descendants added later, by for example addChild().
  • Define childSelector as a function or string that identifies focusable child Elements.

Note the word "child" in this class is used loosely, to refer to any descendant Element. If the child elements contain text though, they should have a label attribute. KeyNav uses the label attribute for letter key navigation.

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Extends

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Members

<protected> _keyNavCodes :Object

Hash mapping key code (arrow keys and home/end key) to functions to handle those keys. Usually not used directly, as subclasses can instead override _onLeftArrow() etc. Must be set before postCreate().

Type:
  • Object
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<protected> _started :boolean

Set to true when startup() has completed.

Type:
  • boolean
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<protected> baseClass :string

Root CSS class of the widget (ex: d-text-box)

Type:
  • string
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<protected, constant> childSelector :string|function

Selector to identify which descendants 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.

By default, the direct DOM children of this widget are considered as the children.

Must be set in the prototype rather than on the instance.

Type:
  • string | function
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<protected> focused :boolean

This widget or a widget it contains has focus, or is "active" because it was recently clicked.

Type:
  • boolean
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Default Value:
  • false
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<protected, readonly> focusedChild :Element

The currently focused descendant, or null if there isn't one

Type:
  • Element
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<protected> template :function

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

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

<protected> _get(name) → {*}

Internal helper for directly accessing an attribute value.

Directly get 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.
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Returns:

Value of property.

Type
*

<protected> _getNext(child, dir) → {Element}

Returns the next or previous navigable child, relative to "child". If "child" is this, then it returns the first focusable child (when dir === 1) or last focusable child (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

<protected> _onBlur()

This is where widgets do processing for when they stop being active, such as changing CSS classes. See onBlur() for more details.

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Called on down arrow key. Should go to the next child in vertical container widgets like Menu.

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<protected> _onFocus()

This is where widgets do processing for when they are active, such as changing CSS classes. See onFocus() for more details.

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Called on left arrow key, or right arrow key if widget is in RTL mode. Should go back to the previous child in horizontal container widgets like Toolbar.

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Called on right arrow key, or left arrow key if widget is in RTL mode. Should go to the next child in horizontal container widgets like Toolbar.

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Called on up arrow key. Should go to the previous child in vertical container widgets like Menu.

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<protected> _parseAttr(name, value)

Helper for _mapAttributes(). Interpret a given attribute specified in markup, returning either:

  • undefined: ignore
  • {prop: prop, value: value}: set this[prop] = value
  • {event: event, callback: callback}: call this.on(event, callback);
Parameters:
Name Type Description
name string

Attribute name.
value string

Attribute value.
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<protected> _parseFunctionAttr(value, params)

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.
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<protected> _set(name, value)

Internal helper for directly setting a property value without calling the custom setter.

Directly change 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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<protected> attachedCallback()

Called when the widget is first inserted into the document. If widget is created programatically then app must call startup() to trigger this method.

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<protected> buildRendering()

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.

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computeProperties(newValues, oldValues)

Callback function to calculate computed properties upon property changes.

Parameters:
Name Type Description
newValues Object

The hash table of new property values, keyed by property names.
oldValues Object

The hash table of old property values, keyed by property names.
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<protected> createdCallback()

Kick off the life-cycle of a widget.

Calls a number of widget methods (preCreate(), buildRendering(), and postCreate()), some of which of you'll want to override.

Of course, adventurous developers could override createdCallback entirely, but this should only be done as a last resort.

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<protected> defer(fcn, delay) → {Object}

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.
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Returns:

Handle with a remove method that deschedules the callback from being called.

Type
Object

deliver()

Synchronously deliver change records for computed properties and then UI rendering so that refreshingRendering() is called if there are pending change records.

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deliverComputing()

Synchronously deliver change records for computed properties so that refreshingComputing() is called if there are pending change records.

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destroy()

Destroy this widget and its descendants.

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discardChanges()

Discard change records.

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discardComputing()

Discard change records for computed properties.

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<protected> emit(type, eventObj) → {boolean}

Signal that a synthetic event occurred.

Emits an event of specified type, based on eventObj. Also calls onType() method, if present, and returns value from that method. Modifies eventObj by adding missing parameters (bubbles, cancelable, widget).

Parameters:
Name Type Argument Description
type string

Name of event.
eventObj Object <optional>

Properties to mix in to emitted event.
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Returns:

True if the event was not canceled, false if it was canceled.

Type
boolean
Example
myWidget.emit("query-success", {});

findCustomElements(root)

Search subtree under root returning custom elements found.

Parameters:
Name Type Argument Description
root Element <optional>

Node to search under.
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focus()

Default focus() implementation: focus the first child.

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<protected> focusChild(child, last)

Focus specified child Element.

Parameters:
Name Type Description
child Element

Reference to container's child.
last boolean

If true and if child has multiple focusable nodes, focus the last one instead of the first one.
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<protected> focusFirstChild()

Focus the first focusable child in the container.

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<protected> focusLastChild()

Focus the last focusable child in the container.

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getEnclosingWidget(node)

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
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getParent()

Returns the parent widget of this widget.

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<protected> isLeftToRight() → {boolean}

Return this widget's explicit or implicit orientation (true for LTR, false for RTL).

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Returns:
Type
boolean

mix(hash)

Set a hash of properties on a Stateful instance.

Parameters:
Name Type Description
hash Object

Hash of properties.
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Example
myObj.mix({
    foo: "Howdy",
    bar: 3
});

notifyCurrentValue(name)

Notify current value to observers. Handy to manually schedule invocation of observer callbacks when there is no change in value.

Parameters:
Name Type Description
name string

The property name.
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observe(callback) → {module:decor/Stateful.PropertyListObserver}

Observe 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 is squashed .

Parameters:
Name Type Description
callback function

The callback.
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Returns:

The observer that can be used to stop observation or synchronously deliver/discard pending change records.

Type
module:decor/Stateful.PropertyListObserver
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;

on(type, func, node) → {Object}

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 widget's scope you must do myWidget.on("click", myWidget.func.bind(myWidget)).

Parameters:
Name Type Argument Description
type string | function

Name of event (ex: "click") or extension event like touch.press.
func function

Callback function.
node Element <optional>

Element to attach handler to, defaults to this.
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Returns:

Handle with remove() method to cancel the event.

Type
Object

onBlur()

Called when the widget stops being "active" because focus moved to something outside of it, or the user clicked somewhere outside of it, or the widget was hidden.

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onFocus(evt)

Called when the widget becomes "active" because it or a widget inside of it either has focus, or has recently been clicked.

Parameters:
Name Type Description
evt Event

A focus event.
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<protected> own() → {Array.<Object>}

Track specified handles and remove/destroy them when this instance is destroyed, unless they were already removed/destroyed manually.

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Returns:

The array of specified handles, so you can do for example: var handle = this.own(on(...))[0];

Type
Array.<Object>

<protected> placeAt(reference, position) → {module:delite/Widget}

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
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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)

<protected> postCreate()

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.

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<protected> preCreate()

Processing before buildRendering().

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<protected> processConstructorParameters()

Called after Object is created to process parameters passed to constructor.

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refreshRendering(newValues, oldValues)

Callback function to render UI upon property changes.

Parameters:
Name Type Description
newValues Object

The hash table of new property values, keyed by property names.
oldValues Object

The hash table of old property values, keyed by property names.
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<protected> setClassComponent(component, value, node)

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.
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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.
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startup()

Processing after the DOM fragment is added to the document.

Called after a widget and its children have been created and added to the page, and all related widgets have finished their create() cycle, up through postCreate().

Note that startup() may be called while the widget is still hidden, for example if the widget is inside a hidden deliteful/Dialog or an unselected tab of a deliteful/TabContainer. For widgets that need to do layout, it's best to put that layout code inside resize(), and then extend delite/LayoutWidget so that resize() is called when the widget is visible.

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