import * as log4javascript from "log4javascript";
import { LoggingEvent } from "log4javascript";
/**
 * Formats a logging event into JavaScript Object Notation (JSON).
 * The implemenatation is mainly the same as with log4javascript.JsonLayout,
 * with an improvement of serializing messages containing '\"'."
 */
export declare class JsonLayout extends log4javascript.JsonLayout {
    /**
     * Formats the log message.
     */
    format(loggingEvent: LoggingEvent): string;
    /**
     * Gets the layout's name.
     * Mainly for unit testing purposes.
     *
     * @return layout's name
     */
    toString(): string;
}