perl -wE ' my $remove = q{<div><div class="blue"></div></div>};
my $str = q{</div></div><div><div class="blue"></div></div>};
say $str =~ s/$remove//r;'

##</code><code>##

perl -wE ' my $remove = qr{<div><div class="blue"></div></div>};
my $str = q{</div></div><div><div class="blue"></div></div>};
say $str =~ s/$remove//r;'

##</code><code>##

perl -wE ' my $remove = m/<div><div class="blue"><\/div><\/div>/;'

Use of uninitialized value $_ in pattern match (m//) at -e line 1.

##</code><code>##

$ perl -wE ' my $remove = q{foo}; my $str = q{barfoobaz}; say $str =~ s/$remove//;'
1

$ perl -wE ' my $remove = q{foo}; my $str = q{barfoobaz}; ( my $x = $str ) =~ s/$remove//; say $x;'
barbaz

$ perl -wE ' my $remove = q{foo}; my $str = q{barfoobaz}; say $str =~ s/$remove//r;'
barbaz