@preact/signals-core/dist/signals-core.d.ts

Manage state with style in every framework

declare const BRAND_SYMBOL: unique symbol;
/**
 * 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.
 *
 * @param fn The callback function.
 * @returns The value returned by the callback.
 */
declare function batch<T>(fn: () => T): T;
/**
 * Run a callback function that can access signal values without
 * subscribing to the signal updates.
 *
 * @param fn The callback function.
 * @returns The value returned by the callback.
 */
declare function untracked<T>(fn: () => T): T;
/**
 * The base class for plain and computed signals.
 */
declare class Signal<T = any> {
    constructor(value?: T, options?: SignalOptions<T>);
    subscribe(fn: (value: T) => void): () => void;
    valueOf(): T;
    toString(): string;
    toJSON(): T;
    peek(): T;
    brand: typeof BRAND_SYMBOL;
    get value(): T;
    set value(value: T);
}
export interface SignalOptions<T = any> {
    watched?: (this: Signal<T>) => void;
    unwatched?: (this: Signal<T>) => void;
}
/**
 * Create a new plain signal.
 *
 * @param value The initial value for the signal.
 * @returns A new signal.
 */
export declare function signal<T>(value: T, options?: SignalOptions<T>): Signal<T>;
export declare function signal<T = undefined>(): Signal<T | undefined>;
/**
 * An interface for read-only signals.
 */
interface ReadonlySignal<T = any> {
    readonly value: T;
    peek(): T;
    subscribe(fn: (value: T) => void): () => void;
    valueOf(): T;
    toString(): string;
    toJSON(): T;
    brand: typeof BRAND_SYMBOL;
}
/**
 * Create a new signal that is computed based on the values of other signals.
 *
 * The returned computed signal is read-only, and its value is automatically
 * updated when any signals accessed from within the callback function change.
 *
 * @param fn The effect callback.
 * @returns A new read-only signal.
 */
declare function computed<T>(fn: () => T, options?: SignalOptions<T>): ReadonlySignal<T>;
type EffectFn = ((this: {
    dispose: () => void;
}) => void | (() => void)) | (() => void | (() => void));
/**
 * Create an effect to run arbitrary code in response to signal changes.
 *
 * An effect tracks which signals are accessed within the given callback
 * function `fn`, and re-runs the callback when those signals change.
 *
 * The callback may return a cleanup function. The cleanup function gets
 * run once, either when the callback is next called or when the effect
 * gets disposed, whichever happens first.
 *
 * @param fn The effect callback.
 * @returns A function for disposing the effect.
 */
declare function effect(fn: EffectFn): {
    (): void;
    [Symbol.dispose](): void;
};
export { computed, effect, batch, untracked, Signal, ReadonlySignal };