API Docs

signalium

state

export function state<T>(
  initialValue: T,
  opts?: StateSignalOptions<T>,
): WriteableSignal<T>;

Creates a new state signal with the given initial value. State signals are mutable values that can trigger reactivity when they change.

WriteableSignal<T> Interface

interface WriteableSignal<T> {
  get(): T; // Get the current value
  set(value: T): void; // Set a new value
  update(updater: (value: T) => T): void; // Update using a function
  peek(): T; // Get the value without creating a dependency
  addListener(listener: (value: T) => void): () => void; // Listen for changes
}

reactive

export function reactive<T, Args extends unknown[]>(
  fn: (...args: Args) => T,
  opts?: DerivedSignalOptions<T, Args>,
): (...args: Args) => ReactiveValue<T>;

Creates a reactive function that tracks dependencies and automatically updates when those dependencies change.

task

export function task<T, Args extends unknown[]>(
  fn: (...args: Args) => Promise<T>,
  opts?: DerivedSignalOptions<T, Args>,
): ReactiveTask<T, Args>;

Creates a reactive task for handling asynchronous operations. Tasks are similar to reactive functions but are specialized for promises.

ReactiveTask<T, Args> Interface

interface ReactiveTask<T, Args extends unknown[]>
  extends ReactivePromise<T, Args> {
  run(...args: Args): ReactivePromise<T>; // Manually trigger the task
}

subscription

export function subscription<T, Args extends unknown[]>(
  fn: SignalSubscribe<T, Args>,
  opts?: DerivedSignalOptionsWithInit<T, Args>,
): ReactiveSubscription<T>;

Creates a reactive subscription for handling long-running, asymmetric async operations like websockets, polling, or event listeners.

ReactiveSubscription<T> Interface

interface ReactiveSubscription<T> extends ReactivePromise<T> {
  rerun(): void; // Manually trigger the subscription to rerun
}

watcher

export function watcher<T>(fn: () => T): Watcher<T>;

Creates a watcher that listens to updates from signals externally. Watchers are how signals are consumed by frameworks and applications.

callback

export function callback<T, Args extends unknown[]>(
  fn: (...args: Args) => T,
): (...args: Args) => T;

Creates a callback function that is owned by the current reactive context. This essentially allows you to use the same contexts as the owner within the callback

createContext

export function createContext<T>(
  initialValue: T,
  description?: string,
): Context<T>;

Creates a context that can be used to provide values to a subtree of reactive functions.

useContext

export function useContext<T>(context: Context<T>): T;

Retrieves the value from a context. Must be called within a reactive function or a component that has a parent provider.

withContexts

export function withContexts<C extends unknown[], U>(
  contexts: [...ContextPair<C>],
  fn: () => U,
): U;

Executes a function with the provided context values, making them available to any reactive function called within.

Watcher<T> Interface

interface Watcher<T> {
  addListener(listener: (value: T) => void): () => void; // Add a listener for changes
  get(): T; // Get the current value and track dependencies
  peek(): T; // Get the current value without tracking dependencies
}

isReactivePromise

export function isReactivePromise<T, Args extends unknown[]>(
  obj: unknown,
): boolean;

Checks if a value is a reactive promise.

isReactiveTask

export function isReactiveTask<T, Args extends unknown[]>(
  obj: unknown,
): boolean;

Checks if a value is a reactive task.

isReactiveSubscription

export function isReactiveSubscription<T, Args extends unknown[]>(
  obj: unknown,
): boolean;

Checks if a value is a reactive subscription.

hashValue

export function hashValue(value: unknown): number;

Generates a consistent hash for a value. Used internally for caching and memoization.

registerCustomHash

export function registerCustomHash<T>(
  ctor: { new (): T },
  hashFn: (obj: T) => number,
): void;

Registers a custom hash function for a specific class. Useful for objects that need special equality considerations.

signalium/react

setupReact

export function setupReact(): void;

Initializes the React integration. Call this once at or near the root of your application.

useStateSignal

export function useStateSignal<T>(
  value: T,
  opts?: SignalOptions<T, unknown[]>,
): WriteableSignal<T>;

Creates a component-scoped state signal that will be cleaned up when the component unmounts.

ContextProvider

export function ContextProvider({
  contexts,
  children,
}: {
  contexts: ContextPair<unknown[]>;
  children: React.ReactNode;
}): React.ReactElement;

A component that provides multiple Signalium contexts to a React component tree.