Show/hide help without querying the server

src/JS.hs

@@ -34,6 +34,7 @@ allJSFunctions = JS . T.unlines . map fromJS $ [
   -- Utilities
   replaceWithData, prependData, appendData,
   moveNodeUp, moveNodeDown,
+  switchSection,
   -- Help
   showOrHideHelp, showHelp, hideHelp,
   -- Search
@@ -160,13 +161,24 @@ moveNodeDown =
       el.next().after(el);
   |]
 
+-- TODO: document the way hiding/showing works
+
+-- | Given something that contains section divs (or spans), show one and
+-- hide the rest. The div/span with the given @class@ will be chosen.
+switchSection :: JSFunction a => a
+switchSection =
+  makeJSFunction "switchSection" ["node", "section"]
+  [text|
+    $(node).children(".section").removeClass("shown");
+    $(node).children(".section."+section).addClass("shown");
+  |]
+
 showHelp :: JSFunction a => a
 showHelp =
   makeJSFunction "showHelp" ["node", "version"]
   [text|
     localStorage.removeItem("help-hidden-"+version);
-    $.get("/render/help", {mode: "shown"})
-     .done(replaceWithData(node));
+    switchSection(node, "expanded");
   |]
 
 hideHelp :: JSFunction a => a
@@ -174,20 +186,19 @@ hideHelp =
   makeJSFunction "hideHelp" ["node", "version"]
   [text|
     localStorage.setItem("help-hidden-"+version, "");
-    $.get("/render/help", {mode: "hidden"})
-     .done(replaceWithData(node));
+    switchSection(node, "collapsed");
   |]
 
+-- TODO: find a better name for this (to distinguish it from 'showHelp' and
+-- 'hideHelp')
 showOrHideHelp :: JSFunction a => a
 showOrHideHelp =
   makeJSFunction "showOrHideHelp" ["node", "version"]
   [text|
     if (localStorage.getItem("help-hidden-"+version) === null)
-      $.get("/render/help", {mode: "shown"})
-       .done(replaceWithData(node))
+      showHelp(node, version)
     else
-      $.get("/render/help", {mode: "hidden"})
-       .done(replaceWithData(node));
+      hideHelp(node, version);
   |]
 
 search :: JSFunction a => a

src/Main.hs

@@ -636,10 +636,6 @@ traitVar = "trait" <//> var
 
 renderMethods :: SpockM () () DB ()
 renderMethods = Spock.subcomponent "render" $ do
-  -- Help
-  Spock.get "help" $ do
-    visible <- param' "mode"
-    lucid $ renderHelp visible
   -- Title of a category
   Spock.get (categoryVar <//> "title") $ \catId -> do
     category <- dbQuery (GetCategory catId)
@@ -839,15 +835,21 @@ renderRoot globalState = do
   -- this file. (This isn't an actual file, so don't look for it in the
   -- static folder – it's generated and served in 'otherMethods'.)
   includeJS "/js.js"
+  -- CSS that makes 'shown' and 'noScriptShown' work
+  noscript_ $ style_ [text|
+    .section:not(.noscript-shown) {display:none;}
+    |]
+  script_ [text|
+    var sheet = document.createElement('style');
+    sheet.innerHTML = '.section:not(.shown) {display:none;}';
+    // “head” instead of “body” because body isn't loaded yet
+    document.head.appendChild(sheet);
+    |]
+  -- Okay, here goes the actual page
+  -- TODO: this header looks bad when the page is narrow
   h1_ "Collaborative notes on Haskell libraries and tools"
-  -- By default help is rendered hidden, and then showOrHideHelp reads a
-  -- value from local storage and decides whether to show help or not. On one
-  -- hand, it means that people with Javascript turned off won't be able to
-  -- see help; on another hand, those people don't need help anyway because
-  -- they won't be able to edit anything either.
-  renderHelp Hidden
-  onPageLoad $ JS.showOrHideHelp (selectId "help", helpVersion)
-  noscript_ $ renderMarkdownBlock [text|
+  noscript_ $ div_ [id_ "noscript-message"] $
+    renderMarkdownBlock [text|
       You have Javascript disabled! This site works fine without Javascript,
       but since all editing needs Javascript to work, you won't be able to edit
       anything. Also, show/hide buttons need Javascript too, so you won't be
@@ -856,6 +858,8 @@ renderRoot globalState = do
       search doesn't work without Javascript either (another thing I should
       really fix – sorry!).
       |]
+  renderHelp
+  onPageLoad $ JS.showOrHideHelp (selectId "help", helpVersion)
   -- TODO: show notes when Javascript is disabled – perhaps by hiding them
   -- by default but putting a “show everything” CSS into a <style> block
   -- inside a <noscript> block
@@ -933,16 +937,17 @@ renderDonate = do
 -- TODO: add a list for “interesting libraries, but too lazy to describe, so
 -- somebody describe them for me”
 
-helpVersion :: Int
-helpVersion = 1
+renderHelp :: HtmlT IO ()
+renderHelp = do
+  div_ [id_ "help"] $ do
 
-renderHelp :: Visible -> HtmlT IO ()
-renderHelp Hidden =
-  div_ [id_ "help"] $
+    -- If you're going to change section names, look at 'JS.showHelp' and
+    -- 'JS.hideHelp'
+    section "collapsed" [shown] $ do
       textButton "show help" $
         JS.showHelp (selectId "help", helpVersion)
-renderHelp Shown =
-  div_ [id_ "help"] $ do
+
+    section "expanded" [noScriptShown] $ do
       textButton "hide help" $
         JS.hideHelp (selectId "help", helpVersion)
       -- Don't forget to change 'helpVersion' when the text changes
@@ -950,6 +955,9 @@ renderHelp Shown =
       help <- liftIO $ T.readFile "static/help.md"
       renderMarkdownBlock help
 
+helpVersion :: Int
+helpVersion = 1
+
 -- TODO: when conflicts happen, maybe create an alert like “The thing you're
 -- editing has been edited in the meantime. Here is a link with a diff of
 -- your variant and the other person's variant. Please merge the changes
@@ -1313,6 +1321,9 @@ textButton caption (JS handler) =
   span_ [class_ "text-button"] $
     a_ [href_ "javascript:void(0)", onclick_ handler] (toHtml caption)
 
+-- TODO: use # instead of javascript:void(0), the latter is slow in Firefox
+-- for me
+
 -- So far all icons used here have been from <https://useiconic.com/open/>
 imgButton :: Url -> [Attribute] -> JS -> HtmlT IO ()
 imgButton src attrs (JS handler) =
@@ -1373,6 +1384,18 @@ instance PathPiece Visible where
 instance ToJS Visible where
   toJS = JS . tshow . toPathPiece
 
+-- Wheh changing these, also look at 'JS.switchSection'.
+
+shown, noScriptShown :: Attribute
+shown          = class_ " shown "
+noScriptShown  = class_ " noscript-shown "
+
+section :: Monad m => Text -> [Attribute] -> HtmlT m () -> HtmlT m ()
+section t attrs = div_ (class_ (t <> " section ") : attrs)
+
+sectionSpan :: Monad m => Text -> [Attribute] -> HtmlT m () -> HtmlT m ()
+sectionSpan t attrs = span_ (class_ (t <> " section ") : attrs)
+
 -- TODO: why not compare Haskellers too?
 
 newGroupValue :: Text

static/css.css

@@ -6,6 +6,10 @@ body {
   font-family: sans-serif;
   line-height: 120%; }
 
+#noscript-message {
+  padding: 1px 1em;
+  background-color: #FFEBEE; }
+
 #footer {
   text-align: center;
   padding: 1.5em 0;