@aria-ui/core

@aria-ui/core

A compact and efficient toolkit for building reactive web components. It powers the Aria UI library, but it can also be used independently.

Key Features

Reactive Signals

Uses signals to manage state reactively and automatically update the DOM in response to state changes. It's powered by the mature and battle-tested @preact/signals-core library.

Context Management

Shares signals easily across widely nested HTML elements through context.

DOM Manipulation Utilities

A comprehensive collection of utilities for DOM interactions, enabling declarative management of attributes, styles, and event listeners.

Interfaces

ReadonlySignal<T>

A read-only signal that holds a reactive value.

Type Parameters

Accessors

value

Methods

get()

get(): T

Get the signal's current value.

peek()

peek(): T

Get the signal's current value without subscribing.

Signal<T>

A mutable signal that can be used to manage reactive state changes.

Type Parameters

Accessors

value

Methods

get()

get(): T

Get the signal's current value.

peek()

peek(): T

Get the signal's current value without subscribing.

set()

set(value: T): void

Set the value of the signal.

Functions

ElementBuilder()

function ElementBuilder<Props>(
  useElement: (host: ConnectableElement, state: SignalState<Props>) => void,
  defaultProps: Props,
): () => BaseElement & Props;

Create a custom element class.

Contexts

Context<T>

A context is a way to provide and consume signals in a HTML tree.

Type Parameters

Methods

consume()

consume(element: ConnectableElement): Signal<T>

Receives the signal from a parent element.

provide()

provide(element: ConnectableElement, signal: Signal<T> | ReadonlySignal<T>): void

Provides a signal to all children of the element.

createContext()

function createContext<T>(key: string | symbol, defaultValue: T): Context<T>;

Creates a new context.

DOM

useAnimationFrame()

function useAnimationFrame(element: ConnectableElement, effect: () => void | () => void | VoidFunction): () => void

Executes an effect in the next animation frame.

The given effect function will be called when the element is connected, and when the dependencies change afterward.

effect could return a function callback. callback will be called in the next animation frame.

callback could return a function dispose. dispose will be called when the effect is disposed.

useAriaAttribute()

function useAriaAttribute<K>(
  element: ConnectableElement,
  key: K,
  compute: () => AriaAttributes[K],
): VoidFunction;

Sets the computed attribute of the element when it's connected.

This is a TypeScript type-safe version of useAttribute.

useAriaRole()

function useAriaRole(element: ConnectableElement, role: AriaRole | () => AriaRole | undefined): VoidFunction

Sets the role attribute of the element when it's connected.

You can pass a string or a compute function that returns a string.

useAttribute()

function useAttribute(
  element: ConnectableElement,
  key: string,
  compute: () => undefined | string | number,
): VoidFunction;

Sets the computed attribute of the element when it's connected.

useEventListener()

function useEventListener<K>(
  element: ConnectableElement,
  type: K,
  listener: (event: HTMLElementEventMap[K]) => void,
  options?: boolean | AddEventListenerOptions,
): VoidFunction;

Registers an event listener on the element.

useQuerySelector()

function useQuerySelector<E>(
  element: ConnectableElement,
  selector: string,
  options: MutationObserverInit,
): ReadonlySignal<E | null>;

Returns the first element matching the given selector.

useQuerySelectorAll()

function useQuerySelectorAll<E>(
  element: ConnectableElement,
  selector: string,
  options: MutationObserverInit,
): ReadonlySignal<NodeListOf<E>>;

Returns all elements matching the given selector.

useStyle()

function useStyle<K>(
  element: ConnectableElement,
  key: K,
  compute: () => CSSStyleDeclaration[K],
): VoidFunction;

Sets the computed style of the element when it's connected.

Elements

BaseElement

Base class for all custom elements in Aria UI. It implements the ConnectableElement interface.

Constructors

new BaseElement(): BaseElement

ConnectableElement

Any HTML element that has implemented the addConnectedCallback method.

Properties

Property	Type	Description
addConnectedCallback	(callback: () => void | VoidFunction) => void	Registers a callback to be called when the element is connected to the DOM. This callback can return a cleanup function that will be called when the element is disconnected from the DOM.

Props and States

SignalState<T>

type SignalState<T>: { [K in keyof T]: Signal<T[K]> };

A plain object containing signals.

Type Parameters

assignProps()

function assignProps<T>(
  defaultProps: Readonly<T>,
  props?: Partial<T>,
): Readonly<T>;

Merges two objects, with the second object taking precedence. Only keys present in the first object will be included in the result.

mapSignals()

function mapSignals<T>(values: T): SignalState<T>;

Maps every value in the given object to a signal.

mapValues()

function mapValues<T>(signals: SignalState<T>): T;

Maps every signal in the given object to its current value.

Signals

SignalValue<S>

type SignalValue<S>: S extends Signal<infer T> ? T : never;

Extracts the value type from a signal type.

Type Parameters

batch()

function batch<T>(fn: () => T): T;

Combine multiple value updates into one "commit" at the end of the provided callback.

Batches can be nested and changes are only flushed once the outermost batch callback completes.

Accessing a signal that has been modified within a batch will reflect its updated value.

createComputed()

function createComputed<T>(fn: () => T): ReadonlySignal<T>;

Creates a computed signal that automatically updates its value based on the reactive dependencies it uses. Computed signals are read-only and are used to derive state from other signals, recalculating their value when dependencies change.

createSignal()

function createSignal<T>(value: T): Signal<T>;

Creates and returns a new signal with the given initial value. Signals are reactive data sources that can be read and written to, allowing components to reactively update when their values change.

untracked()

function untracked<T>(fn: () => T): T;

Run a callback function that can access signal values without subscribing to the signal updates.

useEffect()

function useEffect(
  element: ConnectableElement,
  callback: () => void | VoidFunction,
): () => void;

Registers a callback to be called when the given element is connected to the DOM. It will track which signals are accessed and re-run their callback when those signals change. The callback can return a cleanup function that will be called when the effect is destroyed.

The effect will be destroyed and all signals it was subscribed to will be unsubscribed from, when the element is disconnected from the DOM. You can also manually destroy the effect by calling the returned function.