FileType (identify file MIME-type)

function FileType(filename: string): string

Most file types can be identified regardless of the file name or extension, by simply reading the first 261 bytes of the file itself (no need to read the whole file, so this process is extremely quick and doesn’t waste any RAM).

Here’s a list of file types that this function can identify:

• Image

  • jpg - image/jpeg

  • png - image/png

  • gif - image/gif

  • webp - image/webp

  • cr2 - image/x-canon-cr2

  • tif - image/tiff

  • bmp - image/bmp

  • heif - image/heif

  • jxr - image/vnd.ms-photo

  • psd - image/vnd.adobe.photoshop

  • ico - image/x-icon

  • dwg - image/vnd.dwg

• Video

  • mp4 - video/mp4

  • m4v - video/x-m4v

  • mkv - video/x-matroska

  • webm - video/webm

  • mov - video/quicktime

  • avi - video/x-msvideo

  • wmv - video/x-ms-wmv

  • mpg - video/mpeg

  • flv - video/x-flv

  • 3gp - video/3gpp

• Audio

  • mid - audio/midi

  • mp3 - audio/mpeg

  • m4a - audio/m4a

  • ogg - audio/ogg

  • flac - audio/x-flac

  • wav - audio/x-wav

  • amr - audio/amr

  • aac - audio/aac

• Archive

  • epub - application/epub+zip

  • zip - application/zip

  • tar - application/x-tar

  • rar - application/x-rar-compressed

  • gz - application/gzip

  • bz2 - application/x-bzip2

  • 7z - application/x-7z-compressed

  • xz - application/x-xz

  • pdf - application/pdf

  • exe - application/x-msdownload

  • swf - application/x-shockwave-flash

  • rtf - application/rtf

  • iso - application/x-iso9660-image

  • eot - application/octet-stream

  • ps - application/postscript

  • sqlite - application/x-sqlite3

  • nes - application/x-nintendo-nes-rom

  • crx - application/x-google-chrome-extension

  • cab - application/vnd.ms-cab-compressed

  • deb - application/x-deb

  • ar - application/x-unix-archive

  • Z - application/x-compress

  • lz - application/x-lzip

  • rpm - application/x-rpm

  • elf - application/x-executable

  • dcm - application/dicom

• Documents

  • doc - application/msword

  • docx - application/vnd.openxmlformats-officedocument.wordprocessingml.document

  • xls - application/vnd.ms-excel

  • xlsx - application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

  • ppt - application/vnd.ms-powerpoint

  • pptx - application/vnd.openxmlformats-officedocument.presentationml.presentation

• Font

  • woff - application/font-woff

  • woff2 - application/font-woff

  • ttf - application/font-sfnt

  • otf - application/font-sfnt

• Application

  • wasm - application/wasm