changing pattern by removing spaces?

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http://unix.stackexchange.com – file : hi hello,new york, , ,brazil site ,brazil january,month is feb , , ,indiana jones task: --delete all horizontal space(spaces and tab) between any two coma's(like , ,) if there is no character other than space. so it would look like : hi hello,new york,,,brazil site ,brazil january,month is feb ,,,indiana jones ----also, delete any trailing or leading horizontal space(space and tab) for each parameter so that it looks like this. final output: hi hello,new york,,,brazil site,brazil january,month is feb,,,indiana jones NOTE:The parameters itself has spaces (HowTos)