Regex to check if valid URL that ends in jpg png or gif

Question

I would like users to submit a URL that is valid but also is an image  ending with  jpg   png  or  gif

User · Answer

If you really want to be sure  grabbing the first kilobyte or two of the given URL should be sufficient to determine everything you need to know about the image   Here s an example of how you can get that information  using Python  and here s an example of it being put to use  as a Django form field which allows you to easily validate an image s existence  filesize  dimensions and format  given its URL

User · Answer

http s           w  s -        jpg gif png  worked really well for me    This will match URLs in the following forms   https   farm4 staticflickr com 3894 15008518202 c265dfa55f h jpg http   farm4 staticflickr com 3894 15008518202 c265dfa55f h jpg https   farm4 staticflickr com 3894 15008518202-c265dfa55f-h jpg https   farm4 staticflickr com 3894 15008518202 c265dfa55f h jpg https   farm4 staticflickr com 3894 15008518202 c265dfa55f h gif http   farm4 staticflickr com 3894 15008518202 c265dfa55f h gif https   farm4 staticflickr com 3894 15008518202-c265dfa55f-h gif https   farm4 staticflickr com 3894 15008518202 c265dfa55f h gif https   farm4 staticflickr com 3894 15008518202 c265dfa55f h png http   farm4 staticflickr com 3894 15008518202 c265dfa55f h png https   farm4 staticflickr com 3894 15008518202-c265dfa55f-h png https   farm4 staticflickr com 3894 15008518202 c265dfa55f h png   Check this regular expression against the URLs here  http   regexr com 3g1v7

User · Answer

http s            w  s        jpg gif png    This will mach all images from this string   background  rgb 255  0  0  url    res img temp 634043 original cc3d8715eed0c jpg  repeat fixed left top  cursor  auto   lt div id  divbg  style  background-color  ff0000  gt  lt img id  bg  src     res img temp 634043 original cc3d8715eed0c jpg  width  100   height  100     gt  lt  div gt  background-image  url    res img temp 634043 original cc3d8715eed0c png   background  rgb 255  0  0  url http   google com res    img temp 634043 original cc3     d8715eed0c jpg  repeat fixed left top  cursor  auto  background  rgb 255  0  0  url https   google com res    img temp 634043 original cc3 d8715eed0c jpg  repeat fixed left top  cursor  auto    Test your regex here  https   regex101 com r l2Zt7S 1

User · Answer

http s                  w    w      a-zA-Z  1    w -         w  2 5       d  1 5        w          w    jpg png gif

User · Answer

Use FastImage - it ll grab the minimum required data from the URL to determine if it s an image  what type of image and what size

User · Answer

Actually   Why are you checking the URL  That s no guarantee what you re going to get is an image  and no guarantee that the things you re rejecting aren t images  Try performing a HEAD request on it  and see what content-type it actually is

User · Answer

In general  you re better off validating URLs using built-in library or framework functions  rather than rolling your own regular expressions to do this - see What is the best regular expression to check if a string is a valid URL for details   If you are keen on doing this  though  check out this question   Getting parts of a URL  Regex   Then  once you re satisfied with the URL  by whatever means you used to validate it   you could either use a simple  endswith  type string operator to check the extension  or a simple regex like    i    jpg png gif

User · Answer

Addition to Dan s Answer  If there is an IP address instead of domain  Change regex a bit   Temporary solution for valid IPv4 and IPv6   https        a-z0-9 -       a-z0-9  2 6                   jpg gif png    However this can be improved  for IPv4 and IPv6 to validate subnet range s

User · Answer

Reference  See DecodeConfig section on the official go lang image lib docs here  I believe you could also use DecodeConfig to get the format of an image which you could then validate against const types like jpeg  png  jpg and gif ie  import      encoding base64     fmt     image     log     strings     net http        Package image jpeg is not used explicitly in the code below       but is imported for its initialization side-effect  which allows      image Decode to understand JPEG formatted images  Uncomment these      two lines to also understand GIF and PNG images          image gif          image png       image jpeg        func main       resp  err    http Get  http   i imgur com Peq1U1u jpg     if err    nil         log Fatal err        defer resp Body Close     data     err    image Decode resp Body    if err    nil         log Fatal err        reader    base64 NewDecoder base64 StdEncoding  strings NewReader data     config  format  err    image DecodeConfig reader    if err    nil         log Fatal err        fmt Println  Width    config Width   Height    config Height   Format    format      format here is a string that states the file format eg jpg  png etc

User · Answer

jpg gif png                            That s a  slightly modified  version of the official URI parsing regexp from RFC 2396  It allows for  fragments and  querystrings to appear after the filename  which may or may not be what you want  It also matches any valid domain  including localhost  which again might not be what you want  but it could be modified   A more traditional regexp for this might look like the below    https        a-z0-9 -       a-z  2 6                   jpg gif png              -------- domain ----------- --- path --- -- extension ---   EDIT See my other comment  which although isn t answering the question as completely as this one  I feel it s probably a more useful in this case  However  I m leaving this here for karma-whoring completeness reasons

User · Answer

Here s the basic idea in Perl  Salt to taste       usr bin perl  use LWP  UserAgent   my  ua   LWP  UserAgent- new    ARGV   qw http   www example com logo png    my  response    ua- head   ARGV 0      my   class   type     split m     lc  response- content type   print  It s an image  n  if  class eq  image     If you need to inspect the URL  use a solid library for it rather than trying to handle all the odd situations yourself    use URI   my  uri   URI- new   ARGV 0      my  last      uri- path segments   -1    my   extension      last    m            g   print  My extension is  extension n     Good luck

User · Answer

This expression will match all the image urls -       http s           w -         w  -      w -                amp                   png jpg jpeg gif svg      Examples -  Valid -  https   itelligencegroup com wp-content usermedia de home teaser-box puzzle in the sun png http   sweetytextmessages com wp-content uploads 2016 11 9-Happy-Monday-images jpg example com de home teaser-box puzzle in the sun png www example com de home teaser-box puzzle in the sun png https   www greetingseveryday com wp-content uploads 2016 08 Happy-Independence-Day-Greetings-Cards-Pictures-in-Urdu-Marathi-1 jpg http   thuglifememe com wp-content uploads 2017 12 Top-Happy-tuesday-quotes-1 jpg https   1 bp blogspot com -ejYG9pr06O4 Wlhn48nx9cI AAAAAAAAC7s gAVN3tEV3NYiNPuE-Qpr05TpqLiG79tEQCLcBGAs s1600 Republic-Day-2017-Wallpapers jpg   Invalid -  https   www example com http   www example com www example com example com http   blog example com http   www example com product http   www example com products id 1 amp page 2 http   www example com up http   255 255 255 255 255 255 255 255 http   invalid com perl cgi key    http   web-site com cgi-bin perl cgi key1 value1 amp key2 http   www siteabcd com 8008

[regex] Regex to check if valid URL that ends in .jpg, .png, or .gif

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