import { Primitive, NestedParam, NestedParamArray, Hash } from '../types.mjs';

declare const validKeys: (entry: Record<string, unknown>) => string[];
declare const buildRecursive: (key: string, value: Primitive | NestedParam | NestedParamArray, suffix?: string, encoderFn?: typeof encodeURIComponent) => string;
declare const toQueryString: (entry: undefined | null | Primitive | NestedParam, encoderFn?: typeof encodeURIComponent) => Primitive | null | undefined;
/**
 * Gives time in milliseconds, but with sub-millisecond precision for Browser
 * and Nodejs
 */
declare const performanceNow: () => number;
/**
 * borrowed from: {@link https://gist.github.com/monsur/706839}
 * XmlHttpRequest's getAllResponseHeaders() method returns a string of response
 * headers according to the format described here:
 * {@link http://www.w3.org/TR/XMLHttpRequest/#the-getallresponseheaders-method}
 * This method parses that string into a user-friendly key/value pair object.
 */
declare const parseResponseHeaders: (headerStr: string) => Hash;
declare const lowerCaseObjectKeys: (obj: Hash) => Hash;
declare const assign: {
    <T extends {}, U>(target: T, source: U): T & U;
    <T_1 extends {}, U_1, V>(target: T_1, source1: U_1, source2: V): T_1 & U_1 & V;
    <T_2 extends {}, U_2, V_1, W>(target: T_2, source1: U_2, source2: V_1, source3: W): T_2 & U_2 & V_1 & W;
    (target: object, ...sources: any[]): any;
};
declare const isPlainObject: (value: unknown) => value is Record<string, unknown>;
declare const isObject: (value: unknown) => value is Record<string, unknown>;
declare const btoa: (input: object | Primitive | null) => string;

export { assign, btoa, buildRecursive, isObject, isPlainObject, lowerCaseObjectKeys, parseResponseHeaders, performanceNow, toQueryString, validKeys };