Don't prefetch unknown paths.

index.js

@@ -28,7 +28,7 @@ function loadContentAndInitializeApp(/** @type { init: any  } */ mainElmModule)
     });
 
     app.ports.toJsPort.subscribe((
-      /** @type { HeadTag[] } headTags */ headTags
+      /** @type { { head: HeadTag[], allRoutes: string[] } }  */ fromElm
     ) => {
       appendTag({
         name: "meta",
@@ -37,9 +37,12 @@ function loadContentAndInitializeApp(/** @type { init: any  } */ mainElmModule)
           ["content", `elm-pages v${elmPagesVersion}`]
         ]
       });
+      console.log('allRoutes', fromElm.allRoutes);
+      window.allRoutes = fromElm.allRoutes;
+      
 
       if (navigator.userAgent.indexOf("Headless") >= 0) {
-        headTags.forEach(headTag => {
+        fromElm.head.forEach(headTag => {
           appendTag(headTag);
         });
       } else {
@@ -54,7 +57,7 @@ function loadContentAndInitializeApp(/** @type { init: any  } */ mainElmModule)
   });
 }
 
-function setupLinkPrefetching() {
+function setupLinkPrefetching(allRoutes) {
   new MutationObserver(observeFirstRender).observe(document.body, {
     attributes: true,
     childList: true,
@@ -109,7 +112,7 @@ function setupLinkPrefetchingHelp(
 ) {
   const links = document.querySelectorAll("a");
   links.forEach(link => {
-    // console.log(link.pathname);
+    console.log(link.pathname);
     link.addEventListener("mouseenter", function(event) {
       if (
         event &&
@@ -127,10 +130,13 @@ function setupLinkPrefetchingHelp(
 function prefetchIfNeeded(/** @type {HTMLAnchorElement} */ target) {
   if (target.host === window.location.host) {
     if (prefetchedPages.includes(target.pathname)) {
-      // console.log("Already preloaded", target.href);
-    } else {
+      console.log("Already preloaded", target.href);
+    } else if (!allRoutes.includes(target.pathname)) {
+      console.log("Not a known route, skipping preload", target.pathname);
+    }
+    else {
       prefetchedPages.push(target.pathname);
-      // console.log("Preloading...", target.pathname);
+      console.log("Preloading...", target.pathname);
       const link = document.createElement("link");
       link.setAttribute("as", "fetch");
 

src/Pages/Internal/Platform.elm

@@ -351,9 +351,12 @@ init pathKey canonicalSiteUrl document toJsPort viewFn content initUserModel fla
             )
 
 
-encodeHeads : String -> String -> List (Head.Tag pathKey) -> Json.Encode.Value
-encodeHeads canonicalSiteUrl currentPagePath head =
-    Json.Encode.list (Head.toJson canonicalSiteUrl currentPagePath) head
+encodeHeads : List String -> String -> String -> List (Head.Tag pathKey) -> Json.Encode.Value
+encodeHeads allRoutes canonicalSiteUrl currentPagePath head =
+    Json.Encode.object
+        [ ( "head", Json.Encode.list (Head.toJson canonicalSiteUrl currentPagePath) head )
+        , ( "allRoutes", Json.Encode.list Json.Encode.string allRoutes )
+        ]
 
 
 type Msg userMsg metadata view
@@ -389,7 +392,8 @@ type Phase
 
 
 update :
-    String
+    List String
+    -> String
     ->
         (List ( PagePath pathKey, metadata )
          ->
@@ -416,7 +420,7 @@ update :
     -> Msg userMsg metadata view
     -> ModelDetails userModel metadata view
     -> ( ModelDetails userModel metadata view, Cmd (AppMsg userMsg metadata view) )
-update canonicalSiteUrl viewFunction pathKey onPageChangeMsg toJsPort document userUpdate msg model =
+update allRoutes canonicalSiteUrl viewFunction pathKey onPageChangeMsg toJsPort document userUpdate msg model =
     case msg of
         AppMsg appMsg ->
             case appMsg of
@@ -469,7 +473,7 @@ update canonicalSiteUrl viewFunction pathKey onPageChangeMsg toJsPort document u
                                                     headFn pagePath frontmatter viewResult.staticData
                                                         |> Result.map .head
                                                         |> Result.toMaybe
-                                                        |> Maybe.map (encodeHeads canonicalSiteUrl model.url.path)
+                                                        |> Maybe.map (encodeHeads allRoutes canonicalSiteUrl model.url.path)
                                                         |> Maybe.map toJsPort
 
                                                 ContentCache.NeedContent string metadata ->
@@ -623,8 +627,14 @@ application config =
                             noOpUpdate =
                                 \userMsg userModel ->
                                     ( userModel, Cmd.none )
+
+                            allRoutes =
+                                config.content
+                                    |> List.map Tuple.first
+                                    |> List.map (String.join "/")
+                                    |> List.map (\route -> "/" ++ route)
                         in
-                        update config.canonicalSiteUrl config.view config.pathKey config.onPageChange config.toJsPort config.document userUpdate msg model
+                        update allRoutes config.canonicalSiteUrl config.view config.pathKey config.onPageChange config.toJsPort config.document userUpdate msg model
                             |> Tuple.mapFirst Model
                             |> Tuple.mapSecond (Cmd.map AppMsg)