/** This class is a fallback for browsers that lacks BroadcastChannel but have
 * service workers (which is Safari versions 11.1 through 15.3).
 * Safari 15.4 with BroadcastChannel was released on 2022-03-14.
 * We might be able to remove this class in a near future as Safari < 15.4 is
 * already very low in market share as of 2023-03-10.
 */
export declare class SWBroadcastChannel {
    name: string;
    constructor(name: string);
    subscribe(listener: (message: any) => void): () => void;
    postMessage(message: any): void;
}