/**
 * base64 encode
 *
 * ```ts
 * import { b64EncodeUnicode } from 'sunny-js'
 * console.log(b64EncodeUnicode('hello world'))
 * // => 'aGVsbG8gd29ybGQ='
 * ```
 *
 * 函数依赖btoa，查看[浏览器兼容性](https://developer.mozilla.org/en-US/docs/Web/API/btoa#browser_compatibility)
 *
 * @see [Base64_encoding_and_decoding](https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding#The_Unicode_Problem)
 * @see {@link b64DecodeUnicode}
 * @param str a string prepared to encode by base64
 * @category base64编解码
 */
export declare function b64EncodeUnicode(str: string): string;
/**
 * base64 decode
 *
 * ```ts
 * import { b64DecodeUnicode } from 'sunny-js'
 * console.log(b64DecodeUnicode('aGVsbG8gd29ybGQ'))
 * // => 'hello world'
 * ```
 *
 * 函数依赖atob，查看[浏览器兼容性](https://developer.mozilla.org/en-US/docs/Web/API/atob#browser_compatibility)
 *
 * @see [Base64_encoding_and_decoding](https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding#The_Unicode_Problem)
 * @see {@link b64EncodeUnicode}
 * @param str a string prepared to decode by base64
 * @category base64编解码
 */
export declare function b64DecodeUnicode(str: string): string;