@signaldb/core/dist/Collection/Observer.d.ts

SignalDB is a client-side database that provides a simple MongoDB-like interface to the data with first-class typescript support to achieve an optimistic UI. Data persistence can be achieved by using storage providers that store the data through a JSON in

type AddedCallback<T> = (item: T) => void;
type AddedBeforeCallback<T> = (item: T, before: T) => void;
type ChangedCallback<T> = (item: T) => void;
type ChangedFieldCallback<T> = <Field extends keyof T>(item: T, field: Field, oldValue: T[Field], newValue: T[Field]) => void;
type MovedBeforeCallback<T> = (item: T, before: T) => void;
type RemovedCallback<T> = (item: T) => void;
export interface ObserveCallbacks<T> {
    added?: AddedCallback<T>;
    addedBefore?: AddedBeforeCallback<T>;
    changed?: ChangedCallback<T>;
    changedField?: ChangedFieldCallback<T>;
    movedBefore?: MovedBeforeCallback<T>;
    removed?: RemovedCallback<T>;
}
/**
 * Represents an observer that tracks changes in a collection of items and triggers
 * callbacks for various events such as addition, removal, and modification of items.
 * @template T - The type of the items being observed, which must include an `id` field.
 */
export default class Observer<T extends {
    id: any;
}> {
    private previousItems;
    private callbacks;
    private unbindEvents;
    /**
     * Creates a new instance of the `Observer` class.
     * Sets up event bindings and initializes the callbacks for tracking changes in a collection.
     * @param bindEvents - A function to bind external events to the observer. Must return a cleanup function to unbind those events.
     */
    constructor(bindEvents: () => () => void);
    private call;
    private hasCallbacks;
    /**
     * Determines if the observer has no active callbacks registered for any events.
     * @returns A boolean indicating whether the observer is empty (i.e., no callbacks are registered).
     */
    isEmpty(): boolean;
    /**
     * Compares the previous state of items with the new state and triggers the appropriate callbacks
     * for events such as added, removed, changed, or moved items.
     * @param newItems - The new list of items to compare against the previous state.
     */
    runChecks(newItems: T[]): void;
    /**
     * Stops the observer by unbinding all events and cleaning up resources.
     */
    stop(): void;
    /**
     * Registers callbacks for specific events to observe changes in the collection.
     * @param callbacks - An object containing the callbacks for various events (e.g., 'added', 'removed').
     * @param skipInitial - A boolean indicating whether to skip invoking the callbacks for the initial state of the collection.
     */
    addCallbacks(callbacks: ObserveCallbacks<T>, skipInitial?: boolean): void;
    /**
     * Removes the specified callbacks for specific events, unregistering them from the observer.
     * @param callbacks - An object containing the callbacks to be removed for various events.
     */
    removeCallbacks(callbacks: ObserveCallbacks<T>): void;
}
export {};