/**
 * @summary 获取常用的 MIME 类型。通过文件名后缀查找对应的 MIME 类型。
 *
 * @alias module:Browser.getMimeType
 * @since 5.2.0
 * @see {@link https://developer.mozilla.org/zh-CN/docs/Web/HTTP/MIME_types MIME 类型（IANA 媒体类型）}
 * @see {@link https://www.iana.org/assignments/media-types/media-types.xhtml Media Types}
 * @see 如果需要完整的MIME类型，推荐使用 {@link https://www.npmjs.com/package/mime-type | mime-type}
 * @param {string} fileName 文件名。
 * @returns 如果找到，返回 MIME 类型字符串，否则返回 `undefined`。
 * @example
 * getMimeType('xxx.png'); // 'image/png'
 * getMimeType('xxx.jpg'); // 'image/jpeg'
 * getMimeType('xxx.mp3'); // 'audio/mp3'
 * getMimeType('xxx.mp4'); // 'video/mp4'
 * getMimeType('xxx.pdf'); // 'application/pdf'
 * getMimeType('xxx.zip'); // 'application/zip'
 * getMimeType('xxx.doc'); // 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
 *
 * // 不常用或未知类型
 * getMimeTye('xxx.ci'); // undefined
 *
 * // 非法文件名
 * getMimeType('.zip'); // undefined
 *
 * @description 内置常用的 MIME 类型和文件名后缀映射
 *
 * | MIME 类型 | 文件名后缀 |
 * |---|---|
 * | `text/plain` | `txt` |
 * | `text/css` | `css` |
 * | `text/html` | `htm` `html` |
 * | `text/javascript` | `js` `mjs` |
 * | `text/csv` | `csv` |
 * | `text/markdown` | `md` `markdown` |
 * | `image/gif` | `gif` |
 * | `image/jpeg` | `jpg` `jpeg` `jfif` `pjpeg` `pjp` |
 * | `image/png` | `png` |
 * | `image/svg+xml` | `svg` |
 * | `image/webp` | `webp` |
 * | `image/apng` | `apng` |
 * | `image/avif` | `avif` |
 * | `image/bmp` | `bmp` |
 * | `image/x-icon` | `ico` `cur` |
 * | `image/tiff` | `tif` `tiff` |
 * | `application/xml` | `xml` |
 * | `application/zip` | `zip` |
 * | `application/pdf` | `pdf` |
 * | `application/json` | `json` |
 * | `application/yaml` | `yaml` `yml` |
 * | `application/vnd.openxmlformats-officedocument.wordprocessingml.document` | `doc` `docx` |
 * | `application/vnd.openxmlformats-officedocument.spreadsheetml.sheet` | `xls` `xlsx` |
 * | `audio/mp3` | `mp3` |
 * | `audio/wav` | `wav` |
 * | `audio/aac` | `aac` |
 * | `audio/flac` | `flac` |
 * | `video/mp4` | `mp4` |
 * | `video/ogg` | `ogg` |
 * | `video/webm` | `webm` |
 * | `video/quicktime` | `mov` |
 */
declare function getMimeType(fileName: string): string | undefined;
export default getMimeType;