Command lines in md's fenced blocks that match matching.
Comment lines (#) are skipped: a commented-out example is not a command the
reader is told to run, and flagging it teaches people to delete their examples.
🔴 THE FILTER IS RE-BUILT WITHOUT g/y, BECAUSE RegExp.test IS STATEFUL.
On a global or sticky regex test() advances lastIndex, so testing a run of
matching lines with the SAME object alternates hit/miss. Measured 2026-08-11
on four curl lines: /curl/ finds all four, /curl/g finds the 1st and the
3rd, /curl/y the same. Silent, and the wrong way round — half the document
quietly leaves the set that mustInclude/mustNotInclude then judge, so the
rule passes over commands it never saw. /curl/g is what a caller writes
without thinking, and it must not mean something different.
A fresh regex rather than resetting lastIndex: the caller's object is theirs
and may be reused elsewhere, and there is no state left to reset wrongly. y
goes too — sticky ANCHORS the match at lastIndex, so /curl/y against
sudo curl … would find nothing, which is not what "matching" means here.
Command lines in
md's fenced blocks that matchmatching.Comment lines (
#) are skipped: a commented-out example is not a command the reader is told to run, and flagging it teaches people to delete their examples.🔴 THE FILTER IS RE-BUILT WITHOUT
g/y, BECAUSERegExp.testIS STATEFUL. On a global or sticky regextest()advanceslastIndex, so testing a run of matching lines with the SAME object alternates hit/miss. Measured 2026-08-11 on fourcurllines:/curl/finds all four,/curl/gfinds the 1st and the 3rd,/curl/ythe same. Silent, and the wrong way round — half the document quietly leaves the set thatmustInclude/mustNotIncludethen judge, so the rule passes over commands it never saw./curl/gis what a caller writes without thinking, and it must not mean something different.A fresh regex rather than resetting
lastIndex: the caller's object is theirs and may be reused elsewhere, and there is no state left to reset wrongly.ygoes too — sticky ANCHORS the match atlastIndex, so/curl/yagainstsudo curl …would find nothing, which is not what "matching" means here.