/** A function which can be used as `replacer` or `reviver`. */
export type NjsonFunction = (this: unknown, key: number | string, value: unknown) => unknown;
/** A function that transforms the results or the `Array` of _keys_ to be serialized. */
export type NjsonReplacer = NjsonFunction | (number | string)[];
/** NJSON parsing options. */
export interface NjsonParseOptions {
    /** If `true` the `key` argument passed to `reviver` is of type `number` when reviving an `Array`. */
    numberKey?: boolean;
    /**
     * A function that transforms the results. This function is called for each member of the object.
     * If a member contains nested objects, the nested objects are transformed before the parent object is.
     */
    reviver?: NjsonFunction;
}
/** NJSON serializing options. */
export interface NjsonStringifyOptions {
    /** Specifies the method to be used to serialize `Date` objects. */
    date?: "iso" | "string" | "time" | "utc";
    /** If `true` the `key` argument passed to `replacer` is of type `number` when replacing an `Array`. */
    numberKey?: boolean;
    /** If `true` the `stack` is omitted when serializing `Error` objects. */
    omitStack?: boolean;
    /** A function that transforms the results or the `Array` of _keys_ to be serialized. */
    replacer?: NjsonReplacer;
    /** If `true` the _keys_ of objects are alphabetically sorted before being serialized. */
    sortKeys?: boolean;
    /** Adds indentation, white space, and line break characters to the return-value NJSON text to make it easier to read. */
    space?: number | string;
    /** When a `string` is longer than `stringLength` character it is considered a reference. */
    stringLength?: number;
    /** If `false`, `undefined` values ar skipped (as JSON.stringify does). */
    undef?: boolean;
}
/**
 * Converts a Next JavaScript Object Notation (NJSON) string into an object.
 *
 * @param text A valid NJSON string.
 * @param options A `NjsonParseOptions` specifying the parsing options.
 */
declare function parse<T = unknown>(text: string, options?: NjsonParseOptions): T;
/**
 * Converts a Next JavaScript Object Notation (NJSON) string into an object.
 *
 * @param text A valid NJSON string.
 * @param reviver A function that transforms the results. This function is called for each member of the object.
 * If a member contains nested objects, the nested objects are transformed before the parent object is.
 */
declare function parse<T = unknown>(text: string, reviver?: NjsonFunction): T;
/**
 * Converts a JavaScript value to a Next JavaScript Object Notation (NJSON) string.
 *
 * @param value A JavaScript value, any value, to be converted.
 * @param options A `NjsonStringifyOptions` specifying the serializing options.
 */
declare function stringify(value: unknown, options?: NjsonStringifyOptions): string;
/**
 * Converts a JavaScript value to a Next JavaScript Object Notation (NJSON) string.
 *
 * @param value A JavaScript value, any value, to be converted.
 * @param replacer A function that transforms the results or the `Array` of _keys_ to be serialized.
 * @param space Adds indentation, white space, and line break characters to the return-value NJSON text to make it easier to read.
 */
declare function stringify(value: unknown, replacer?: NjsonReplacer | null, space?: number | string): string;
/** Next JavaScript Object Notation. */
export declare const NJSON: {
    readonly parse: typeof parse;
    readonly stringify: typeof stringify;
};
declare global {
    namespace Express {
        interface Response {
            /**
             * Sends NJSON response.
             *
             * @param body A value sent as body.
             * @param options A `NjsonStringifyOptions` specifying the body serializing options; defaults to `ExpressNjsonOptions.stringify` passed to `expressNJSON`.
             */
            njson(body?: any, options?: NjsonStringifyOptions): Promise<unknown>;
        }
    }
    interface Response {
        /**
         * Parses the response body with `NJSON.parse`.
         *
         * @param options A `NjsonParseOptions` specifying the body parsing options; defaults to `options` passed to `fetchNJSON`.
         */
        readonly njson: (options?: NjsonParseOptions) => Promise<unknown>;
    }
}
/** `expressNJSON` middleware options. */
export interface ExpressNjsonOptions {
    /** A `NjsonParseOptions` specifying the body parsing options. */
    parse?: NjsonParseOptions;
    /** A `NjsonStringifyOptions` specifying the body serializing options; can be overridden while calling `res.njson()`. */
    stringify?: NjsonStringifyOptions;
}
/**
 * An Express middleware which works as NJSON body parser and installs the `Express.Response.njson` method.
 *
 * @param options A `ExpressNjsonOptions` specifying the options to be used while serializing and parsing bodies.
 */
export declare function expressNJSON(options?: ExpressNjsonOptions): (req: any, res: any, next: any) => any;
/**
 * Installs the `Response.njson` method.
 *
 * @param options The default `NjsonParseOptions` specifying the body parsing options.
 */
export declare function fetchNJSON(options?: NjsonParseOptions): void;
export {};