Detect browser support of RFC5987

Question

As the fact there are some historical reason and bugs in some browsers (desktop and mobile), not all of them support rfc5987, rfc2231, rfc6266 and others. I'd like to detect it and do some workaround. How can I do the detection especially there are unknown number of mobile browsers? Test Cases for HTTP Content-Disposition header field (RFC 6266) and the Encodings defined in RFCs 2047, 2231 and 5987 JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

Don't; the mess Content-Disposition is in partly is caused by servers attempting to do user agent detection and getting it wrong. For desktop browsers the problem is well-understood; either special case IE<9 and Safari, or send them both filename and filename* and let them fallback to ASCII. For mobile browsers I would encourage to do the same: Firefox supports filename*, Android's browser (when I last checked) didn't support non-ASCII at all, and Safari didn't "save as" anyway.