JS: Split v2rw.js into plain.js and elm.js, only include JS files when necessary

The trace_log showed that the vast majority of pageviews do not need any
Elm modules at all, so we can save a lot by not loading them on the page.

Some pages (most notably: VN pages for not-logged-in visitors) do need
JS but don't load any Elm modules. I've added a 'js' flag to
HTML::framework_() to indicate that and ensure that plain.js is still
loaded.

5 files changed, 10 insertions, 14 deletions

diff --git a/lib/VNDB/Util/LayoutHTML.pm b/lib/VNDB/Util/LayoutHTML.pm
index 6bafbeda..a18542f8 100644
--- a/lib/VNDB/Util/LayoutHTML.pm
+++ b/lib/VNDB/Util/LayoutHTML.pm
@@ -35,7 +35,6 @@ sub htmlFooter { # %options => { pref_code => 1 }
     noscript id => 'pref_code', title => $self->authGetCode('/xml/prefs.xml'), ''
       if $o{pref_code} && $self->authInfo->{id};
     script type => 'text/javascript', src => $self->{url_static}.'/f/vndb.js?'.$self->{version}, '';
-    VNWeb::HTML::v2rwjs_() if $o{v2rwjs};
    end 'body';
   end 'html';
 }
diff --git a/lib/VNWeb/HTML.pm b/lib/VNWeb/HTML.pm
index 4231b3c1..25df6152 100644
--- a/lib/VNWeb/HTML.pm
+++ b/lib/VNWeb/HTML.pm
@@ -403,19 +403,11 @@ sub _hidden_msg_ {
 }
 
 
-sub v2rwjs_ { # Also used by VNDB::Util::LayoutHTML.
-    script_ type => 'application/json', id => 'pagevars', sub {
-        # Escaping rules for a JSON <script> context are kinda weird, but more efficient than regular xml_escape().
-        lit_(JSON::XS->new->canonical->encode(tuwf->req->{pagevars}) =~ s{</}{<\\/}rg =~ s/<!--/<\\u0021--/rg);
-    } if keys tuwf->req->{pagevars}->%*;
-    script_ type => 'application/javascript', src => config->{url_static}.'/f/v2rw.js?'.config->{version}, '';
-}
-
-
 # Options:
 #   title      => $title
 #   index      => 1/0, default 0
 #   feeds      => 1/0
+#   js         => 1/0, set to 1 to ensure 'plain.js' is included on the page even if no elm_() modules are loaded.
 #   search     => $query
 #   og         => { opengraph metadata }
 #   type       => Database entry type (used for the main tabs & hidden message)
@@ -441,7 +433,12 @@ sub framework_ {
                 $cont->() unless $o{hiddenmsg} && _hidden_msg_ \%o;
                 div_ id => 'footer', \&_footer_;
             };
-            v2rwjs_;
+            script_ type => 'application/json', id => 'pagevars', sub {
+                # Escaping rules for a JSON <script> context are kinda weird, but more efficient than regular xml_escape().
+                lit_(JSON::XS->new->canonical->encode(tuwf->req->{pagevars}) =~ s{</}{<\\/}rg =~ s/<!--/<\\u0021--/rg);
+            } if keys tuwf->req->{pagevars}->%*;
+            script_ type => 'application/javascript', src => config->{url_static}.'/f/elm.js?'.config->{version}, '' if tuwf->req->{pagevars}{elm};
+            script_ type => 'application/javascript', src => config->{url_static}.'/f/plain.js?'.config->{version}, '' if $o{js} || tuwf->req->{pagevars}{elm};
         }
     }
 }
diff --git a/lib/VNWeb/User/Lists.pm b/lib/VNWeb/User/Lists.pm
index dbfd0aea..bbc986d2 100644
--- a/lib/VNWeb/User/Lists.pm
+++ b/lib/VNWeb/User/Lists.pm
@@ -567,7 +567,7 @@ TUWF::get qr{/$RE{uid}/ulist}, sub {
             : $num_core_labels == 1 && $opt_labels->{5} ? 'wish' : 'list';
 
     my $title = $own ? 'My list' : user_displayname($u)."'s list";
-    framework_ title => $title, type => 'u', dbobj => $u, tab => $tab,
+    framework_ title => $title, type => 'u', dbobj => $u, tab => $tab, js => 1,
         $own ? ( pagevars => {
             uid         => $u->{id}*1,
             labels      => $LABELS->analyze->{keys}{labels}->coerce_for_json($labels),
diff --git a/lib/VNWeb/User/Notifications.pm b/lib/VNWeb/User/Notifications.pm
index 618328a4..59512f05 100644
--- a/lib/VNWeb/User/Notifications.pm
+++ b/lib/VNWeb/User/Notifications.pm
@@ -111,7 +111,7 @@ TUWF::get qr{/$RE{uid}/notifies}, sub {
         'ORDER BY n.id', $opt->{r} ? 'DESC' : 'ASC'
     );
 
-    framework_ title => 'My notifications',
+    framework_ title => 'My notifications', js => 1,
     sub {
         div_ class => 'mainbox', sub {
             h1_ 'My notifications';
diff --git a/lib/VNWeb/VN/Page.pm b/lib/VNWeb/VN/Page.pm
index c3feac4a..d5c4b202 100644
--- a/lib/VNWeb/VN/Page.pm
+++ b/lib/VNWeb/VN/Page.pm
@@ -772,7 +772,7 @@ TUWF::get qr{/$RE{vrev}}, sub {
 
     enrich_item $v;
 
-    framework_ title => $v->{title}, index => !tuwf->capture('rev'), type => 'v', dbobj => $v, hiddenmsg => 1, og => og($v),
+    framework_ title => $v->{title}, index => !tuwf->capture('rev'), type => 'v', dbobj => $v, hiddenmsg => 1, js => 1, og => og($v),
     sub {
         rev_ $v if tuwf->capture('rev');
         infobox_ $v;