javascript regex for extracting filename from Content-Disposition header

Question

Content-disposition header contains filename which can be easily extracted, but sometimes it contains double quotes, sometimes no quotes and there are probably some other va

Answer 1

Disclaimer: the following answer only works with PCRE (e.g. Python / PHP), if you have to use javascript, use Robin's answer.

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This modified version of Robin's regex strips the quotes:

filename[^;\n=]*=(['\"])*(.*)(?(1)\1|)

filename        # match filename, followed by
[^;=\n]*        # anything but a ;, a = or a newline
=
(['"])*         # either single or double quote, put it in capturing group 1
(?:utf-8\'\')?  # removes the utf-8 part from the match
(.*)            # second capturing group, will contain the filename
(?(1)\1|)       # if clause: if first capturing group is not empty,
                # match it again (the quotes), else match nothing

https://regex101.com/r/hJ7tS6/28

The filename is in the second capturing group.