feat(toc): scroll the active item into view on mount (#173)

* chore: add fake navigation to the ToC story

* feat: scroll active item into view on initial render

Author: Marcell Toth

src/TableOfContents/index.tsx

@@ -216,6 +216,14 @@ function DefaultRowImpl<T extends TableOfContentsItem>({ item, isExpanded, toggl
   const isActive = item.isActive && !showSkeleton;
   const isDisabled = item.isDisabled;
 
+  const holderCallbackRef = React.useCallback((e: HTMLDivElement) => {
+    if (e && isActive) {
+      e.scrollIntoView({ block: 'center' });
+    }
+    // we only want this on initial render
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
   let icon = item.icon;
   if (item.activeIcon && (isActive || isSelected)) {
     icon = item.activeIcon;
@@ -289,7 +297,12 @@ function DefaultRowImpl<T extends TableOfContentsItem>({ item, isExpanded, toggl
   ) : null;
 
   return (
-    <div onClick={onClick} className={outerClassName} style={{ marginLeft: (item.depth ?? 0) * 24 }}>
+    <div
+      onClick={onClick}
+      className={outerClassName}
+      style={{ marginLeft: (item.depth ?? 0) * 24 }}
+      ref={holderCallbackRef}
+    >
       <div className={cn('-ml-px', innerClassName, { 'opacity-75': isDisabled })}>
         <div className="flex flex-row items-center">
           {icon && (

src/__stories__/TableOfContents/index.tsx

@@ -17,11 +17,7 @@ const styles = {
 storiesOf('TableOfContents', module)
   .addDecorator(withKnobs)
   .add('studio /w custom RowComponent', () => {
-    return (
-      <div style={styles}>
-        <TableOfContents className="h-full" contents={studioContents} rowComponent={RowComponent} />
-      </div>
-    );
+    return <CustomComponentStory />;
   })
   .add('studio without rowComponent', () => {
     return (
@@ -52,8 +48,42 @@ const MobileStory = () => {
   );
 };
 
-const RowComponent: RowComponentType<ITableOfContentsLink> = props => (
-  <a href={props.item.to}>
-    <DefaultRow {...props} />
-  </a>
-);
+const NavigationContext = React.createContext({ path: '', setPath: (_: string) => {} });
+
+const CustomComponentStory = () => {
+  const [path, setPath] = React.useState('/reference/petstore/openapi.v1.yaml/paths/~1pets~1{petId}/get');
+
+  const contextValue = React.useMemo(() => ({ path, setPath }), [path, setPath]);
+
+  const contentsWithDynamicIsActive = React.useMemo(() => {
+    return studioContents.map(c => ({ ...c, isActive: c.to === path }));
+  }, [path]);
+
+  return (
+    <NavigationContext.Provider value={contextValue}>
+      <div style={styles}>
+        <TableOfContents className="h-full" contents={contentsWithDynamicIsActive} rowComponent={RowComponent} />
+      </div>
+    </NavigationContext.Provider>
+  );
+};
+
+const RowComponent: RowComponentType<ITableOfContentsLink> = props => {
+  const { setPath } = React.useContext(NavigationContext);
+
+  const handleClick = React.useCallback(
+    (e: React.MouseEvent) => {
+      if (props.item.to) {
+        setPath(props.item.to);
+      }
+      e.preventDefault();
+    },
+    [props.item.to, setPath],
+  );
+
+  return (
+    <a href={props.item.to} onClick={handleClick}>
+      <DefaultRow {...props} />
+    </a>
+  );
+};