feature(banner): add blog announcement banner

client/src/app.scss

@@ -73,10 +73,10 @@
   --top-navigation-height: 4rem;
   --top-navigation-offset: -4rem;
   --top-banner-inner-height: 3.125rem;
-  // top-banner-inner-height + 2 * padding + 2 * border;
-  --top-banner-height: calc(
-    var(--top-banner-inner-height) + 2 * 0.125rem + 2 * 1px
-  );
+  // top-banner-inner-height + 2 * padding;
+  --top-banner-height: calc(var(--top-banner-inner-height) + 2 * 0.125rem);
+  // + border
+  --top-banner-outer-height: calc(var(--top-banner-height) + 2 * 1px);
 
   --z-index-back: -1;
   --z-index-top: 9999;
@@ -101,10 +101,11 @@
   );
 }
 
-.top-banner.visible ~ * {
+.top-banner.visible ~ *,
+.top-banner.loading ~ * {
   --sticky-header-height: calc(
     var(--top-nav-height) + var(--article-actions-container-height) +
-      var(--top-banner-height) + 2px
+      var(--top-banner-outer-height) + 2px
   );
 }
 

client/src/app.tsx

@@ -35,7 +35,6 @@ const Sitemap = React.lazy(() => import("./sitemap"));
 
 function Layout({ pageType, children }) {
   const { pathname } = useLocation();
-  const isServer = useIsServer();
   const [category, setCategory] = React.useState<string | null>(
     getCategoryByPathname(pathname)
   );
@@ -52,7 +51,7 @@ function Layout({ pageType, children }) {
           category ? `category-${category}` : ""
         } ${pageType}`}
       >
-        {!isServer && <TopPlacement />}
+        <TopPlacement />
         {pageType !== "document-page" && (
           <TopNavigation extraClasses="main-document-header-container" />
         )}

client/src/document/index.scss

@@ -9,7 +9,8 @@
   top: 0;
   z-index: var(--z-index-top);
   @media screen and (min-width: $screen-md) {
-    .top-banner.visible ~ & {
+    .top-banner.visible ~ &,
+    .top-banner.loading ~ & {
       top: var(--top-banner-height);
     }
   }

client/src/placement-context.tsx

@@ -9,6 +9,7 @@ export enum Status {
   success = "success",
   geoUnsupported = "geo_unsupported",
   capReached = "cap_reached",
+  loading = "loading",
 }
 
 export interface Fallback {
@@ -19,7 +20,7 @@ export interface Fallback {
   by: string;
 }
 
-export interface PlacementStatus {
+export interface PlacementData {
   status: Status;
   click: string;
   view: string;
@@ -36,7 +37,10 @@ export interface PlacementStatus {
 }
 
 type PlacementType = "side" | "top";
-type PlacementData = Record<PlacementType, PlacementStatus>;
+export interface PlacementContextData
+  extends Partial<Record<PlacementType, PlacementData>> {
+  status: Status;
+}
 
 const PLACEMENT_MAP: Record<PlacementType, RegExp> = {
   side: /\/[^/]+\/(docs\/|blog\/|search$|_homepage)/i,
@@ -50,7 +54,7 @@ function placementTypes(pathname: string): string[] {
 }
 
 export const PlacementContext = React.createContext<
-  PlacementData | null | undefined
+  PlacementContextData | null | undefined
 >(undefined);
 
 export function PlacementProvider(props: { children: React.ReactNode }) {
@@ -63,7 +67,7 @@ export function PlacementProvider(props: { children: React.ReactNode }) {
     isLoading,
     isValidating,
     mutate,
-  } = useSWR<PlacementData>(
+  } = useSWR<PlacementContextData>(
     !PLACEMENT_ENABLED ||
       user?.settings?.noAds ||
       !placementTypes(location.pathname)
@@ -88,8 +92,8 @@ export function PlacementProvider(props: { children: React.ReactNode }) {
       }
 
       try {
-        const placementResponse: PlacementData = await response.json();
-        gleanClick(`pong: pong->status ${placementResponse.side.status}`);
+        const placementResponse: PlacementContextData = await response.json();
+        gleanClick(`pong: pong->status ${placementResponse.side?.status}`);
         return placementResponse;
       } catch (e) {
         throw Error(response.statusText);
@@ -110,7 +114,9 @@ export function PlacementProvider(props: { children: React.ReactNode }) {
   }, [location.pathname, mutate]);
 
   return (
-    <PlacementContext.Provider value={isLoading || isValidating ? null : pong}>
+    <PlacementContext.Provider
+      value={isLoading || isValidating ? { status: Status.loading } : pong}
+    >
       {props.children}
     </PlacementContext.Provider>
   );

client/src/telemetry/constants.ts

@@ -31,6 +31,7 @@ export const TOGGLE_PLUS_OFFLINE_DISABLED = "toggle_plus_offline_disabled";
 export const TOGGLE_PLUS_OFFLINE_ENABLED = "toggle_plus_offline_enabled";
 export const TOGGLE_PLUS_ADS_FREE_DISABLED = "toggle_plus_ads_free_disabled";
 export const TOGGLE_PLUS_ADS_FREE_ENABLED = "toggle_plus_ads_free_enabled";
+export const BANNER_BLOG_LAUNCH_CLICK = "banner_blog_launch_click";
 
 export const PLUS_UPDATES = Object.freeze({
   EVENT_COLLAPSE: "plus_updates_event_collapse",

client/src/ui/organisms/placement/index.scss

@@ -68,6 +68,7 @@ section.place {
     font-size: 0.625rem;
 
     grid-template-areas: "pong pong pong" "no space note";
+    height: var(--top-banner-height);
     margin: 0 auto;
     width: 100%;
 
@@ -139,20 +140,34 @@ section.place {
   --place-top-cta-color: var(--background-secondary);
 
   background-color: var(--place-top-background);
+
+  border-bottom: 1px solid var(--border-primary);
+  height: var(--top-banner-height);
   position: sticky;
   top: 0;
   z-index: var(--z-index-top);
 
-  &.empty {
-    height: 0;
-  }
-
-  &.visible {
-    border: 1px solid var(--border-primary);
-    height: fit-content;
+  &.fallback {
+    position: initial;
   }
 
   @media screen and (max-width: #{$screen-md - 1}) {
     display: none;
   }
+
+  .fallback-copy {
+    font-size: 1rem;
+    grid-column: 1/4;
+    line-height: var(--top-banner-height);
+    margin: 0 auto;
+
+    a:not(.button) {
+      color: var(--apis-accent-color);
+
+      &:hover,
+      &:focus {
+        text-decoration: underline;
+      }
+    }
+  }
 }

client/src/ui/organisms/placement/index.tsx

@@ -4,7 +4,12 @@ import { useUserData } from "../../../user-context";
 
 import "./index.scss";
 import { useGleanClick } from "../../../telemetry/glean-context";
-import { PlacementStatus, usePlacement } from "../../../placement-context";
+import {
+  PlacementData,
+  Status,
+  usePlacement,
+} from "../../../placement-context";
+import { BANNER_BLOG_LAUNCH_CLICK } from "../../../telemetry/constants";
 
 interface Timer {
   timeout: number | null;
@@ -13,7 +18,7 @@ interface Timer {
 }
 
 function viewed(
-  pong: PlacementStatus,
+  pong: PlacementData,
   observer: IntersectionObserver | null = null
 ) {
   navigator?.sendBeacon?.(
@@ -41,7 +46,26 @@ export function SidePlacement() {
   );
 }
 
+function Fallback() {
+  const gleanClick = useGleanClick();
+
+  return (
+    <p className="fallback-copy">
+      Discover the latest web development insights on our new{" "}
+      <a
+        href="/en-US/blog/"
+        onClick={() => {
+          gleanClick(BANNER_BLOG_LAUNCH_CLICK);
+        }}
+      >
+        MDN Blog
+      </a>
+    </p>
+  );
+}
+
 export function TopPlacement() {
+  const isServer = useIsServer();
   const placementData = usePlacement();
   const { textColor, backgroundColor, ctaTextColor, ctaBackgroundColor } =
     placementData?.top?.colors || {};
@@ -54,13 +78,21 @@ export function TopPlacement() {
     ].filter(([_, v]) => Boolean(v))
   );
 
+  const status =
+    isServer || placementData?.status === Status.loading
+      ? "loading"
+      : placementData?.top
+      ? "visible"
+      : "fallback";
+
   return (
-    <div
-      className={`top-banner ${placementData?.top ? "visible" : "empty"}`}
-      style={css}
-    >
-      {!placementData?.top ? (
-        <section className="place top container"></section>
+    <div className={`top-banner ${status}`} style={css}>
+      {isServer || !placementData?.top ? (
+        <section className="place top container">
+          {!isServer && placementData?.status !== Status.loading && (
+            <Fallback />
+          )}
+        </section>
       ) : (
         <PlacementInner
           pong={placementData.top}
@@ -80,7 +112,7 @@ export function PlacementInner({
   imageWidth,
   imageHeight,
 }: {
-  pong: PlacementStatus;
+  pong: PlacementData;
   extraClassNames?: string[];
   cta?: string;
   imageWidth?: number;