If you want to be very strict about the pattern of the string (including the comma).

perl -e '$a = "1,234,340 views";print "$1\n" if($a =~ /^((?:\d{1,3})?(
+?:,\d{3})*) views$/);'
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I think using "^" will speed up things a bit (although a few nanoseconds won't make much difference) when compared to similar regex without "^".