Use $RE{comment}{JavaScript} from Regexp::Common::comment:

use warnings;
use strict;
use Regexp::Common qw/comment/;

my $sample = <<'END_SAMPLE';
Hello
// World
a /* test */ b
xyz /* asdf
qwertz /*
uiop */ ijk
END_SAMPLE

$sample =~ s/$RE{comment}{JavaScript}//g;

print $sample;

__END__

Hello
a  b
xyz  ijk
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