Added back scroll locking

src/assets/javascripts/bundle.ts

@@ -64,7 +64,8 @@ import {
 } from "./integrations"
 import {
   patchIndeterminate,
-  patchScrollfix
+  patchScrollfix,
+  patchScrolllock
 } from "./patches"
 
 /* ----------------------------------------------------------------------------
@@ -128,6 +129,7 @@ keyboard$
 /* Set up patches */
 patchIndeterminate({ document$ })
 patchScrollfix({ document$ })
+patchScrolllock({ viewport$, tablet$ })
 
 /* Set up header and main area observable */
 const header$ = watchHeader(getComponentElement("header"), { viewport$ })
@@ -208,4 +210,5 @@ window.viewport$  = viewport$          /* Viewport observable */
 window.tablet$    = tablet$            /* Tablet observable */
 window.screen$    = screen$            /* Screen observable */
 window.print$     = print$             /* Print mode observable */
+window.alert$     = alert$             /* Alert subject */
 window.component$ = component$         /* Component observable */

src/assets/javascripts/patches/index.ts

@@ -22,3 +22,4 @@
 
 export * from "./indeterminate"
 export * from "./scrollfix"
+export * from "./scrolllock"

src/assets/javascripts/patches/scrolllock/index.ts

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2016-2021 Martin Donath <martin.donath@squidfunk.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+import {
+  Observable,
+  animationFrameScheduler,
+  combineLatest,
+  of
+} from "rxjs"
+import {
+  delay,
+  map,
+  observeOn,
+  switchMap,
+  withLatestFrom
+} from "rxjs/operators"
+
+import { resetScrollLock, setScrollLock } from "~/actions"
+import { Viewport, watchToggle } from "~/browser"
+
+/* ----------------------------------------------------------------------------
+ * Helper types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Patch options
+ */
+interface PatchOptions {
+  viewport$: Observable<Viewport>      /* Viewport observable */
+  tablet$: Observable<boolean>         /* Tablet breakpoint observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Patch the document body to lock when search is open
+ *
+ * For mobile and tablet viewports, the search is rendered full screen, which
+ * leads to scroll leaking when at the top or bottom of the search result. This
+ * function locks the body when the search is in full screen mode, and restores
+ * the scroll position when leaving.
+ *
+ * @param options - Options
+ */
+export function patchScrolllock(
+  { viewport$, tablet$ }: PatchOptions
+): void {
+  combineLatest([watchToggle("search"), tablet$])
+    .pipe(
+      map(([active, tablet]) => active && !tablet),
+      switchMap(active => of(active)
+        .pipe(
+          delay(active ? 400 : 100),
+          observeOn(animationFrameScheduler)
+        )
+      ),
+      withLatestFrom(viewport$)
+    )
+      .subscribe(([active, { offset: { y }}]) => {
+        if (active)
+          setScrollLock(document.body, y)
+        else
+          resetScrollLock(document.body)
+      })
+}