fast-element

Classes

Class	Description
AttributeDefinition	An implementation of `Accessor` that supports reactivity, change callbacks, attribute reflection, and type conversion for custom elements.
ChildrenDirective	The runtime behavior for child node observation.
DefaultExecutionContext	The default execution context for template views.
ElementController	Controls the lifecycle and rendering of a `FASTElement`.
ElementStyles	Represents styles that can be applied to a custom element.
FASTElementDefinition	Defines metadata for a FASTElement.
HTMLBindingDirective	The central binding directive that bridges data expressions and DOM updates. HTMLBindingDirective fulfills three roles simultaneously: - HTMLDirective: Produces placeholder HTML via createHTML() during template authoring. - ViewBehaviorFactory: Creates behaviors (returns itself) during view creation. - ViewBehavior / EventListener: Attaches to a DOM node during bind, manages expression observers for reactive updates, and handles DOM events directly. The aspectType (set by HTMLDirective.assignAspect during template processing) determines which DOM "sink" function is used to apply values — e.g., setAttribute for attributes, addEventListener for events, textContent for content.
HTMLView	The standard View implementation, which also implements ElementView and SyntheticView.
InlineTemplateDirective	Inlines a template into another template.
PropertyChangeNotifier	An implementation of Notifier that allows subscribers to be notified of individual property changes on an object.
RefDirective	The runtime behavior for template references.
RenderBehavior	A Behavior that enables advanced rendering.
RenderDirective	A Directive that enables use of the RenderBehavior.
RepeatBehavior	A behavior that renders a template for each item in an array.
RepeatDirective	A directive that configures list rendering.
Schema	A constructed JSON schema from a template
SlottedDirective	The runtime behavior for slotted node observation.
Sort	A sort array indicates new index positions of array items.
Splice	A splice map is a representation of how a previous array of items was transformed into a new array of items. Conceptually it is a list of tuples of (index, removed, addedCount) which are kept in ascending index order of. The tuple represents that at the \|index\|, \|removed\| sequence of items were removed, and counting forward from \|index\|, \|addedCount\| items were added.
SubscriberSet	An implementation of Notifier that efficiently keeps track of subscribers interested in a specific change notification on an observable subject.
ViewTemplate	A template capable of creating HTMLView instances or rendering directly to DOM.

Abstract Classes

Abstract Class	Description
Binding	Captures a binding expression along with related information and capabilities.
NodeObservationDirective	A base class for node observation.
StatelessAttachedAttributeDirective	A base class used for attribute directives that don't need internal state.

Enumerations

Enumeration	Description
Stages	The various lifecycle stages of an ElementController.

Functions

Function	Description
attr(config)	Decorator: Specifies an HTML attribute.
attr(target, prop)	Decorator: Specifies an HTML attribute.
children(propertyOrOptions)	A directive that observes the `childNodes` of an element and updates a property whenever they change.
composedContains(reference, test)	Determines if the reference element contains the test element in a "composed" DOM tree that ignores shadow DOM boundaries. Returns true of the test element is a descendent of the reference, or exists in a shadow DOM that is a logical descendent of the reference. Otherwise returns false.
composedParent(element)	Retrieves the "composed parent" element of a node, ignoring DOM tree boundaries. When the parent of a node is a shadow-root, it will return the host element of the shadow root. Otherwise it will return the parent node or null if no parent node exists.
computedState(initialize, name)	*(BETA)* Creates a ComputedState.
cssDirective()	Decorator: Defines a CSSDirective.
customElement(nameOrDef)	Decorator: Defines a platform custom element based on `FASTElement`.
elements(selector)	Creates a function that can be used to filter a Node array, selecting only elements.
enableDebug()	Enables human-readable FAST debug messages.
htmlDirective(options)	Decorator: Defines an HTMLDirective.
lengthOf(array)	Enables observing the length of an array.
listener(expression, options)	Creates an event listener binding.
normalizeBinding(value)	Normalizes the input value into a binding.
observable(target, nameOrAccessor)	Decorator: Defines an observable property on the target.
oneTime(expression, policy)	Creates a one time binding
oneWay(expression, policy, isVolatile)	Creates an standard binding.
ownedState(value, options)	*(BETA)* Creates a reactive state that has its value associated with a specific owner.
reactive(object, deep)	*(BETA)* Converts a plain object to a reactive, observable object.
ref(propertyName)	A directive that observes the updates a property with a reference to the element.
render(value, template)	Creates a RenderDirective for use in advanced rendering scenarios.
repeat(items, template, options)	A directive that enables list rendering.
signal(expression, options, policy)	Creates a signal binding configuration with the supplied options.
slotted(propertyOrOptions)	A directive that observes the `assignedNodes()` of a slot and updates a property whenever they change.
sortedCount(array)	Enables observing the sorted property of an array.
state(value, options)	*(BETA)* Creates a reactive state value.
twoWay(expression, optionsOrChangeEvent, policy, isBindingVolatile)	Creates a default binding.
volatile(target, name, descriptor)	Decorator: Marks a property getter as having volatile observable dependencies.
watch(object, subscriber)	*(BETA)* Deeply subscribes to changes in existing observable objects.
when(condition, templateOrTemplateBinding, elseTemplateOrTemplateBinding)	A directive that enables basic conditional rendering in a template.

Interfaces

Interface	Description
AccessCachedPath	A path discovered from an access expression.
Accessor	Represents a getter/setter property accessor on an object.
ArrayObserver	An observer for arrays.
Aspected	Represents something that applies to a specific aspect of the DOM.
BindingDirective	The directive from which a binding originates.
CachedPathCommon	Common metadata for paths cached while parsing a template.
CaptureType	A marker interface used to capture types when interpolating Directive helpers into templates.
ChildListDirectiveOptions	The options used to configure child list observation.
ChildrenMap	Describes a child custom element binding referenced by a schema path.
ContentTemplate	A simple template that can create ContentView instances.
ContentView	A simple View that can be interpolated into HTML content.
CSSDirective	Directive for use in CSS templates.
CSSDirectiveDefinition	Defines metadata for a CSSDirective.
DefaultCachedPath	A path discovered from a default binding.
Disposable	Provides a mechanism for releasing resources.
ElementControllerStrategy	A type that instantiates an ElementController
ElementView	A View representing DOM nodes specifically for rendering the view of a custom element.
ElementViewTemplate	A template capable of creating views specifically for rendering custom elements.
EventCachedPath	A path discovered from an event binding.
ExecutionContext	Provides additional contextual information available to behaviors and expressions.
ExpressionController	Controls the lifecycle of an expression and provides relevant context.
ExpressionNotifier	Enables evaluation of and subscription to a binding.
ExpressionObserver	Observes an expression for changes.
FASTElement	Represents a custom element based on the FASTElement infrastructure.
HostBehavior	Represents an object that can contribute behavior to a host.
HostController	Controls the lifecycle and context of behaviors and styles associated with a component host.
HTMLDirective	Instructs the template engine to apply behavior to a node.
HTMLDirectiveDefinition	Defines metadata for an HTMLDirective.
HTMLTemplateCompilationResult	The result of a template compilation operation.
JSONSchema	A JSON schema describing a root property.
JSONSchemaCommon	Common properties shared by schema nodes.
JSONSchemaDefinition	A reusable JSON schema definition.
LengthObserver	Observes array lengths.
NodeBehaviorOptions	Options for configuring node observation behavior.
Notifier	Provides change notifications for an observed subject.
ObservationRecord	A record of observable property access.
PartialFASTElementDefinition	Represents metadata configuration for a custom element.
PartialHTMLDirectiveDefinition	Represents metadata configuration for an HTMLDirective.
RegisterPathConfig	Configuration for registering a path with a schema.
RepeatCachedPath	A path discovered from a repeat directive.
RepeatOptions	Options for configuring repeat behavior.
ShadowRootOptions	Shadow root initialization options.
SlottedDirectiveOptions	The options used to configure slotted node observation.
SortObserver	Observes array sort.
SpliceStrategy	An approach to tracking changes in an array.
StyleStrategy	Implemented to provide specific behavior when adding/removing styles for elements.
StyleTarget	A node that can be targeted by styles.
Subscriber	Implemented by objects that are interested in change notifications.
SubtreeDirectiveOptions	The options used to configure subtree observation.
SyntheticView	A view representing a range of DOM nodes which can be added/removed ad hoc.
SyntheticViewTemplate	A template capable of rendering views not specifically connected to custom elements.
TemplateLifecycleCallbacks	Lifecycle callbacks for template events.
TwoWaySettings	The settings required to enable two-way binding.
UpdateQueue	A work queue used to synchronize writes to the DOM.
ValueConverter	Represents objects that can convert values to and from view or model representations.
View	Represents a collection of DOM nodes which can be bound to a data source.
ViewBehavior	Represents an object that can contribute behavior to a view.
ViewBehaviorFactory	A factory that can create a ViewBehavior associated with a particular location within a DOM fragment.
ViewBehaviorOrchestrator	Bridges between ViewBehaviors and HostBehaviors, enabling a host to control ViewBehaviors.
ViewController	Controls the lifecycle of a view and provides relevant context.

Variables

Variable	Description
ArrayObserver	An observer for arrays.
AttributeConfiguration	Metadata used to configure a custom attribute's behavior.
booleanConverter	A ValueConverter that converts to and from `boolean` values.
Compiler	Common APIs related to compilation.
css	Transforms a template literal string into styles.
CSSDirective	Instructs the css engine to provide styles during CSS template composition.
DOM	Common DOM APIs.
DOMAspect	The type of HTML aspect to target.
DOMPolicy	A helper for creating DOM policies.
emptyArray	A readonly, empty array.
ExecutionContext	Provides additional contextual information available to behaviors and expressions.
FAST	The FAST messaging API for warnings and errors.
FASTElement	A minimal base class for FASTElements that also provides static helpers for working with FASTElements.
html	Transforms a template literal string into a ViewTemplate.
HTMLDirective	Instructs the template engine to apply behavior to a node.
Markup	Common APIs related to markup generation.
nullableBooleanConverter	A ValueConverter that converts to and from `boolean` values. `null`, `undefined`, `""`, and `void` values are converted to `null`.
nullableNumberConverter	A ValueConverter that converts to and from `number` values.
Observable	Common Observable APIs.
Parser	Common APIs related to content parsing.
schemaRegistry	Module-level registry that maps custom element names to their schema maps. Used for cross-element `$ref` resolution (e.g. nested element schemas). Each Schema instance registers itself here on construction.
Signal	The gateway to signal APIs.
SourceLifetime	Describes how the source's lifetime relates to its controller's lifetime.
SpliceStrategy	Functionality related to tracking changes in arrays.
SpliceStrategySupport	Indicates what level of feature support the splice strategy provides.
TwoWaySettings	Enables configuring two-way binding settings.
Updates	The default UpdateQueue.
ViewBehaviorOrchestrator	Bridges between ViewBehaviors and HostBehaviors, enabling a host to control ViewBehaviors.

Type Aliases

Type Alias	Description
AddViewBehaviorFactory	Used to add behavior factories when constructing templates.
AttributeConfiguration	Metadata used to configure a custom attribute's behavior.
AttributeMode	The mode that specifies the runtime behavior of the attribute.
CachedPath	A path discovered while parsing a template.
CachedPathMap	A map from element names and root properties to JSON schemas.
Callable	Represents a callable type such as a function or an object with a "call" method.
ChildrenDirectiveOptions	The options used to configure child/subtree node observation.
Class	Represents a constructable class with a prototype.
CompilationStrategy	A function capable of compiling a template from the preprocessed form produced by the html template function into a result that can instantiate views.
CompiledViewBehaviorFactory	Represents a ViewBehaviorFactory after the compilation process has completed.
ComposableStyles	Represents styles that can be composed into the ShadowDOM of a custom element.
ComputedBuilder	*(BETA)* Provides computed state capabilities.
ComputedInitializer	*(BETA)* A callback that initializes the computation.
ComputedSetupCallback	*(BETA)* A callback that enables computation setup.
ComputedState	*(BETA)* State whose value is computed from other dependencies.
Constructable	Represents a type which can be constructed with the new operator.
ConstructibleStyleStrategy	A type that instantiates a StyleStrategy.
CSSTemplateTag	Transforms a template literal string into styles.
CSSValue	Represents the types of values that can be interpolated into a template.
DecoratorAttributeConfiguration	Metadata used to configure a custom attribute's behavior through a decorator.
DOMAspect	The type of HTML aspect to target.
DOMAspectGuards	Aspect-specific guards for a DOM Policy.
DOMElementGuards	Element-specific guards for a DOM Policy.
DOMGuards	Guard configuration for a DOM Policy.
DOMPolicyOptions	Options for creating a DOM Policy.
DOMSink	A function used to send values to a DOM sink.
DOMSinkGuards	A specific DOM sink guard for a node aspect.
ElementsFilter	Elements filter function type.
Expression	The signature of an arrow function capable of being evaluated against source data and within an execution context.
FASTElementExtension	A callback that receives a FASTElementDefinition during element registration. Extensions are invoked before the element is registered with the platform, allowing plugins to inspect or act on the resolved definition.
FASTElementTemplateResolver	Resolves an element template from a composed definition.
HTMLTemplateTag	Transforms a template literal string into a ViewTemplate.
OwnedState	*(BETA)* A read/write stateful value associated with an owner.
ReadonlyOwnedState	*(BETA)* A readonly stateful value associated with an object owner.
ReadonlyState	*(BETA)* A readonly stateful value.
SourceLifetime	Describes how the source's lifetime relates to its controller's lifetime.
SpliceStrategySupport	The available values for SpliceStrategySupport.
State	*(BETA)* A read/write stateful value.
StateOptions	*(BETA)* Options for creating state.
TemplateValue	Represents the types of values that can be interpolated into a template.
TrustedTypesPolicy	A policy for use with the standard trustedTypes platform API.
TwoWayBindingOptions	The twoWay binding options.
ViewBehaviorTargets	The target nodes available to a behavior.