Fixed scroll offset when activating linked content tabs

material/base.html

@@ -245,7 +245,7 @@
       </script>
     {% endblock %}
     {% block scripts %}
-      <script src="{{ 'assets/javascripts/bundle.48f2be22.min.js' | url }}"></script>
+      <script src="{{ 'assets/javascripts/bundle.d691e9de.min.js' | url }}"></script>
       {% for path in config.extra_javascript %}
         <script src="{{ path | url }}"></script>
       {% endfor %}

src/assets/javascripts/bundle.ts

@@ -213,7 +213,7 @@ const content$ = defer(() => merge(
 
   /* Content */
   ...getComponentElements("content")
-    .map(el => mountContent(el, { target$, print$ })),
+    .map(el => mountContent(el, { viewport$, target$, print$ })),
 
   /* Search highlighting */
   ...getComponentElements("content")

src/assets/javascripts/components/content/_/index.ts

@@ -22,7 +22,7 @@
 
 import { Observable, merge } from "rxjs"
 
-import { getElements } from "~/browser"
+import { Viewport, getElements } from "~/browser"
 
 import { Component } from "../../_"
 import { Annotation } from "../annotation"
@@ -68,6 +68,7 @@ export type Content =
  * Mount options
  */
 interface MountOptions {
+  viewport$: Observable<Viewport>      /* Viewport observable */
   target$: Observable<HTMLElement>     /* Location target observable */
   print$: Observable<boolean>          /* Media print observable */
 }
@@ -88,7 +89,7 @@ interface MountOptions {
  * @returns Content component observable
  */
 export function mountContent(
-  el: HTMLElement, { target$, print$ }: MountOptions
+  el: HTMLElement, { viewport$, target$, print$ }: MountOptions
 ): Observable<Component<Content>> {
   return merge(
 
@@ -110,6 +111,6 @@ export function mountContent(
 
     /* Content tabs */
     ...getElements("[data-tabs]", el)
-      .map(child => mountContentTabs(child))
+      .map(child => mountContentTabs(child, { viewport$ }))
   )
 }

src/assets/javascripts/components/content/tabs/index.ts

@@ -37,11 +37,13 @@ import {
   subscribeOn,
   takeLast,
   takeUntil,
-  tap
+  tap,
+  withLatestFrom
 } from "rxjs"
 
 import { feature } from "~/_"
 import {
+  Viewport,
   getElement,
   getElementContentOffset,
   getElementContentSize,
@@ -66,6 +68,17 @@ export interface ContentTabs {
   active: HTMLLabelElement             /* Active tab label */
 }
 
+/* ----------------------------------------------------------------------------
+ * Helper types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Mount options
+ */
+interface MountOptions {
+  viewport$: Observable<Viewport>      /* Viewport observable */
+}
+
 /* ----------------------------------------------------------------------------
  * Functions
  * ------------------------------------------------------------------------- */
@@ -102,11 +115,12 @@ export function watchContentTabs(
  * this functionality ourselves.
  *
  * @param el - Content tabs element
+ * @param options - Options
  *
  * @returns Content tabs component observable
  */
 export function mountContentTabs(
-  el: HTMLElement
+  el: HTMLElement, { viewport$ }: MountOptions
 ): Observable<Component<ContentTabs>> {
 
   /* Render content tab previous button for pagination */
@@ -189,23 +203,44 @@ export function mountContentTabs(
 
     /* Set up linking of content tabs, if enabled */
     if (feature("content.tabs.link"))
-      push$.pipe(skip(1))
-        .subscribe(({ active }) => {
+      push$.pipe(
+        skip(1),
+        withLatestFrom(viewport$)
+      )
+        .subscribe(([{ active }, { offset }]) => {
           const tab = active.innerText.trim()
-          for (const set of getElements("[data-tabs]"))
-            for (const input of getElements<HTMLInputElement>(
-              ":scope > input", set
-            )) {
-              const label = getElement(`label[for="${input.id}"]`)
-              if (label.innerText.trim() === tab) {
-                input.click()
-                break
-              }
-            }
+          if (active.hasAttribute("data-md-switching")) {
+            active.removeAttribute("data-md-switching")
 
-          /* Persist active tabs in local storage */
-          const tabs = __md_get<string[]>("__tabs") || []
-          __md_set("__tabs", [...new Set([tab, ...tabs])])
+          /* Determine viewport offset of active tab */
+          } else {
+            const y = el.offsetTop - offset.y
+
+            /* Passively activate other tabs */
+            for (const set of getElements("[data-tabs]"))
+              for (const input of getElements<HTMLInputElement>(
+                ":scope > input", set
+              )) {
+                const label = getElement(`label[for="${input.id}"]`)
+                if (
+                  label !== active &&
+                  label.innerText.trim() === tab
+                ) {
+                  label.setAttribute("data-md-switching", "")
+                  input.click()
+                  break
+                }
+              }
+
+            /* Bring active tab into view */
+            window.scrollTo({
+              top: el.offsetTop - y
+            })
+
+            /* Persist active tabs in local storage */
+            const tabs = __md_get<string[]>("__tabs") || []
+            __md_set("__tabs", [...new Set([tab, ...tabs])])
+          }
         })
 
     /* Create and return component */