/**
 * Slightly modernized version of [`base64-js`][1].
 * Performance is slightly improved due to pre-allocating arrays.
 *
 * This version drops support for platforms that don't provide
 * `Uint8Array` and `DataView`. Use the original in those cases.
 *
 * [1]: https://github.com/beatgammit/base64-js
 * [2]: https://tools.ietf.org/html/rfc3986#section-2.3
 */
/**
 * Takes a base 64 string and converts it to an array buffer.
 * Accepts both regular Base64 and the URL-friendly variant,
 * where `+` => `-`, `/` => `_`, and the padding character is omitted.
 *
 * @param str A Base64 string in either regular or  URL-friendly representation.
 * @returns The binary data as `Uint8Array`.
 */
export declare function toByteArray(str: string): Uint8Array;
/**
 * Encodes binary data provided in an array buffer as a Base64 string.
 * @param bufferSource The raw data to encode.
 * @param urlFriendly Set to true to encode in a URL-friendly way.
 * @returns The contents a Base64 string.
 */
export declare function fromByteArray(bufferSource: BufferSource, urlFriendly?: boolean): string;
export { fromByteArray as encode, toByteArray as decode, };