fix(JumpLinks): updated demo code for active item (#12590)

Author: thatblindgeye

packages/react-core/src/components/JumpLinks/JumpLinks.tsx

@@ -142,6 +142,10 @@ export const JumpLinks: React.FunctionComponent<JumpLinksProps> = ({
       return;
     }
     const scrollPosition = Math.ceil(scrollableElement.scrollTop + offset);
+    // Take into account the last section not having enough content to trigger a scroll position; without
+    // checking if at the bottom of the scroll container, the last JumpLinksItem never becomes "active".
+    const isAtBottom =
+      Math.ceil(scrollableElement.scrollTop + scrollableElement.clientHeight) >= scrollableElement.scrollHeight;
     window.requestAnimationFrame(() => {
       let newScrollItems = scrollItems;
       // Items might have rendered after this component or offsetTop values may need
@@ -153,6 +157,11 @@ export const JumpLinks: React.FunctionComponent<JumpLinksProps> = ({
         setScrollItems(newScrollItems);
       }
 
+      if (isAtBottom) {
+        const lastIndex = newScrollItems.length - 1;
+        return setActiveIndex(lastIndex);
+      }
+
       const scrollElements = newScrollItems
         .map((e, index) => ({
           y: e ? e.offsetTop : null,

packages/react-core/src/demos/examples/JumpLinks/JumpLinksScrollspy.tsx

@@ -72,7 +72,7 @@ export const JumpLinksScrollspy: React.FunctionComponent = () => {
                 isVertical={isVertical}
                 isCentered={!isVertical}
                 label="Jump to section"
-                scrollableSelector=".pf-v6-c-page__main-container"
+                scrollableSelector=".pf-v6-c-page__main"
                 offset={offsetHeight}
                 expandable={{ default: isVertical ? 'expandable' : 'nonExpandable', md: 'nonExpandable' }}
                 isExpanded