@hypothesis/frontend-shared/lib/util/listener-collection.d.ts

Shared components, styles and utilities for Hypothesis projects

export type Listener = {
    eventTarget: EventTarget;
    eventType: string;
    listener: EventListener;
    options?: AddEventListenerOptions;
};
/**
 * Return the event type that a listener will receive.
 *
 * For example `EventType<HTMLElement, 'keydown'>` evaluates to `KeyboardEvent`.
 *
 * The event type is extracted from the target's `on${Type}` property (eg.
 * `HTMLElement.onkeydown` here) If there is no such property, the type defaults
 * to `Event`.
 */
export type EventType<Target extends EventTarget, TypeName extends string> = `on${TypeName}` extends keyof Target ? Target[`on${TypeName}`] extends ((...args: any[]) => void) | null ? Parameters<NonNullable<Target[`on${TypeName}`]>>[0] : Event : Event;
/**
 * Utility that provides a way to conveniently remove a set of DOM event
 * listeners when they are no longer needed.
 */
export declare class ListenerCollection {
    private _listeners;
    constructor();
    /**
     * Add a listener and return an ID that can be used to remove it later
     */
    add<ListenerTarget extends EventTarget, Type extends string>(eventTarget: ListenerTarget, eventType: Type, listener: (event: EventType<ListenerTarget, Type>) => void, options?: AddEventListenerOptions): symbol;
    /**
     * Remove a specific listener.
     */
    remove(listenerId: symbol): void;
    removeAll(): void;
}