This is not -- stroked --  => This is not -- stroked --
This is not --stroked --  => This is not --stroked --
This is not -- stroked--  => This is not -- stroked--
This is --stroked-- => This is <del>stroked</del>
This is --a-- stroke => This is <del>a</del> stroke
This is --a-- short stroke-- => This is <del>a</del> short stroke--
This is --all -- stroked-- => This is <del>all -- stroked</del>
This is --all --stroked-- => This is <del>all --stroked</del>
This is --one--stroked-- => This is <del>one</del>stroked--
--a-- => <del>a</del>
More --strokes-- on a --line-- => More <del>strokes</del> on a <del>line</del>
The extra dashes are ----inside--- => The extra dashes are <del>--inside-</del>
This--is--stroked => This<del>is</del>stroked
--Eeny--meeny--miny--moe-- => <del>Eeny</del>meeny<del>miny</del>moe--
-- Eeny--meeny--miny--moe-- => ...<li>Eeny<del>meeny</del>miny<del>moe</del></li>...
this is a ------ line => this is a <hr/> line
-- this is a list item-- => ...<li>this is a list item--</li>...
HTML <!-- comments are ignored --> => HTML <!-- comments are ignored -->
Multiple HTML <!-- comments --> are <!-- ignored --> => Multiple HTML <!-- comments --> are <!-- ignored -->
Ignore --things-- inside <script> n = --i; m = i--; </script> => Ignore <del>things</del> inside <script> n = --i; m = i--; </script>
Ignore <a href="/some--page--with--dashes">attributes</a> => Ignore <a href="/some--page--with--dashes">attributes</a>

Multiline examples:
This is not --not
stroked--
 => 
This is not --not
stroked--

<script>
m = --i; n = i--;
</script>
m = --i; n = i--;
 =>
<script>
m = --i; n = i--;
</script>
m = <del>i; n = i</del>;