import { Handler, Runner, Value } from './types';
export declare const urlParams: URLSearchParams;
export type SettingValue = null | Value;
export type SettingFn = Runner | Handler<SettingValue>;
/**
 * Define all available settings and their default values here.
 */
export declare const settings: Record<string, SettingValue | SettingFn>;
/**
 * Get the value of a setting, respecting the precedence of settings (cache, URL, sessionStorage, localStorage, default).
 *
 * @param setting - The key/name of the setting to get.
 * @returns - The value of the setting, if it exists in the URL, sessionStorage, localStorage, or defaults.
 */
export declare function getOverrideFor(setting: string): SettingValue;
/**
 * Add a setting to the settings object with a default value and define a getter/setter
 * that respects the precedence of settings (URL, sessionStorage, localStorage, default).
 * Cache all set/retrieved values in the current window for speed.
 *
 * @param setting - The key/name of the setting to add.
 * @param defaultValue - The default value of the setting.
 */
export declare function addSetting(setting: string, defaultValue?: SettingValue): void;
/**
 * Add multiple settings at once.
 *
 * @param newSettings - An object with keys as setting names and values as default values.
 */
export declare function addSettings(newSettings: Record<string, SettingValue>): void;
/**
 * Registers a handler function to be called when the specified setting is set.
 */
export declare function onSetting(setting: string, handler: (value: SettingValue) => void): void;
/**
 * Looks for a meta element with the key as a name and returns the content attribute
 * so long as it doesn't still have its #{octopus} format. Otherwise returns null.
 */
export declare function meta(key: string): string | null;
/**
 * Add a convenience function to the settings object.
 *
 * @param name - The name of the function to add.
 * @param fn - The function to add.
 */
export declare function addFn(name: string, fn: SettingFn): void;
/**
 * Add multiple convenience functions to the settings object.
 *
 * @param fns - An object with keys as function names and values as functions.
 */
export declare function addFns(fns: Record<string, Handler<SettingValue>>): void;
/**
 * Set the backend to a new URL and reload the page.
 */
export declare function setBackend(url: string): string;
export declare function hideFeatures(features: SettingValue): void;
export default settings;