Refactored project structure

material/base.html

@@ -34,7 +34,7 @@
       {% endif %}
     {% endblock %}
     {% block styles %}
-      <link rel="stylesheet" href="{{ 'assets/stylesheets/main.b5f74394.min.css' | url }}">
+      <link rel="stylesheet" href="{{ 'assets/stylesheets/main.b29cf17d.min.css' | url }}">
       {% if config.theme.palette %}
         {% set palette = config.theme.palette %}
         <link rel="stylesheet" href="{{ 'assets/stylesheets/palette.9204c3b2.min.css' | url }}">
@@ -211,7 +211,7 @@
       </script>
     {% endblock %}
     {% block scripts %}
-      <script src="{{ 'assets/javascripts/bundle.0d86bc28.min.js' | url }}"></script>
+      <script src="{{ 'assets/javascripts/bundle.4fa4ff07.min.js' | url }}"></script>
       {% for path in config["extra_javascript"] %}
         <script src="{{ path | url }}"></script>
       {% endfor %}

material/overrides/main.html

@@ -16,5 +16,5 @@
 {% endblock %}
 {% block scripts %}
   {{ super() }}
-  <script src="{{ 'overrides/assets/javascripts/bundle.2a83b894.min.js' | url }}"></script>
+  <script src="{{ 'overrides/assets/javascripts/bundle.5ee92cf1.min.js' | url }}"></script>
 {% endblock %}

src/assets/javascripts/_/index.ts

@@ -20,7 +20,7 @@
  * IN THE SOFTWARE.
  */
 
-import { getElementOrThrow, getLocation } from "~/browser"
+import { getElement, getLocation } from "~/browser"
 
 /* ----------------------------------------------------------------------------
  * Types
@@ -99,7 +99,7 @@ export interface Config {
 /**
  * Retrieve global configuration and make base URL absolute
  */
-const script = getElementOrThrow("#__config")
+const script = getElement("#__config")
 const config: Config = JSON.parse(script.textContent!)
 config.base = `${new URL(config.base, getLocation())}`
 

src/assets/javascripts/browser/document/index.ts

@@ -23,8 +23,7 @@
 import {
   ReplaySubject,
   Subject,
-  fromEvent,
+  fromEvent
-  mapTo
 } from "rxjs"
 
 /* ----------------------------------------------------------------------------
@@ -40,12 +39,9 @@ import {
  * @returns Document subject
  */
 export function watchDocument(): Subject<Document> {
-  const document$ = new ReplaySubject<Document>()
+  const document$ = new ReplaySubject<Document>(1)
-  fromEvent(document, "DOMContentLoaded")
+  fromEvent(document, "DOMContentLoaded", { once: true })
-    .pipe(
+    .subscribe(() => document$.next(document))
-      mapTo(document)
-    )
-      .subscribe(document$)
 
   /* Return document */
   return document$

src/assets/javascripts/browser/element/_/index.ts

@@ -24,72 +24,6 @@
  * Functions
  * ------------------------------------------------------------------------- */
 
-/**
- * Retrieve an element matching the query selector
- *
- * @template T - Element type
- *
- * @param selector - Query selector
- * @param node - Node of reference
- *
- * @returns Element or nothing
- */
-export function getElement<T extends keyof HTMLElementTagNameMap>(
-  selector: T, node?: ParentNode
-): HTMLElementTagNameMap[T] | undefined
-
-export function getElement<T extends HTMLElement>(
-  selector: string, node?: ParentNode
-): T | undefined
-
-export function getElement<T extends HTMLElement>(
-  selector: string, node: ParentNode = document
-): T | undefined {
-  return node.querySelector<T>(selector) || undefined
-}
-
-/**
- * Retrieve an element matching a query selector or throw a reference error
- *
- * @template T - Element type
- *
- * @param selector - Query selector
- * @param node - Node of reference
- *
- * @returns Element
- */
-export function getElementOrThrow<T extends keyof HTMLElementTagNameMap>(
-  selector: T, node?: ParentNode
-): HTMLElementTagNameMap[T]
-
-export function getElementOrThrow<T extends HTMLElement>(
-  selector: string, node?: ParentNode
-): T
-
-export function getElementOrThrow<T extends HTMLElement>(
-  selector: string, node: ParentNode = document
-): T {
-  const el = getElement<T>(selector, node)
-  if (typeof el === "undefined")
-    throw new ReferenceError(
-      `Missing element: expected "${selector}" to be present`
-    )
-
-  /* Return element */
-  return el
-}
-
-/**
- * Retrieve the currently active element
- *
- * @returns Element or nothing
- */
-export function getActiveElement(): HTMLElement | undefined {
-  return document.activeElement instanceof HTMLElement
-    ? document.activeElement
-    : undefined
-}
-
 /**
  * Retrieve all elements matching the query selector
  *
@@ -114,16 +48,73 @@ export function getElements<T extends HTMLElement>(
   return Array.from(node.querySelectorAll<T>(selector))
 }
 
+/**
+ * Retrieve an element matching a query selector or throw a reference error
+ *
+ * Note that this function assumes that the element is present. If unsure if an
+ * element is existent, use the `getOptionalElement` function instead.
+ *
+ * @template T - Element type
+ *
+ * @param selector - Query selector
+ * @param node - Node of reference
+ *
+ * @returns Element
+ */
+export function getElement<T extends keyof HTMLElementTagNameMap>(
+  selector: T, node?: ParentNode
+): HTMLElementTagNameMap[T]
+
+export function getElement<T extends HTMLElement>(
+  selector: string, node?: ParentNode
+): T
+
+export function getElement<T extends HTMLElement>(
+  selector: string, node: ParentNode = document
+): T {
+  const el = getOptionalElement<T>(selector, node)
+  if (typeof el === "undefined")
+    throw new ReferenceError(
+      `Missing element: expected "${selector}" to be present`
+    )
+
+  /* Return element */
+  return el
+}
+
 /* ------------------------------------------------------------------------- */
 
 /**
- * Replace an element with the given list of nodes
+ * Retrieve an optional element matching the query selector
  *
- * @param el - Element
+ * @template T - Element type
- * @param nodes - Replacement nodes
+ *
+ * @param selector - Query selector
+ * @param node - Node of reference
+ *
+ * @returns Element or nothing
  */
-export function replaceElement(
+export function getOptionalElement<T extends keyof HTMLElementTagNameMap>(
-  el: HTMLElement, ...nodes: Node[]
+  selector: T, node?: ParentNode
-): void {
+): HTMLElementTagNameMap[T] | undefined
-  el.replaceWith(...nodes)
+
+export function getOptionalElement<T extends HTMLElement>(
+  selector: string, node?: ParentNode
+): T | undefined
+
+export function getOptionalElement<T extends HTMLElement>(
+  selector: string, node: ParentNode = document
+): T | undefined {
+  return node.querySelector<T>(selector) || undefined
+}
+
+/**
+ * Retrieve the currently active element
+ *
+ * @returns Element or nothing
+ */
+export function getActiveElement(): HTMLElement | undefined {
+  return document.activeElement instanceof HTMLElement
+    ? document.activeElement || undefined
+    : undefined
 }

src/assets/javascripts/browser/element/index.ts

@@ -25,3 +25,4 @@ export * from "./focus"
 export * from "./offset"
 export * from "./selection"
 export * from "./size"
+export * from "./visibility"

src/assets/javascripts/browser/element/offset/_/index.ts

@@ -0,0 +1,77 @@
+/*
+ * 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,
+  fromEvent,
+  map,
+  startWith
+} from "rxjs"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Element offset
+ */
+export interface ElementOffset {
+  x: number                            /* Horizontal offset */
+  y: number                            /* Vertical offset */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve element offset
+ *
+ * @param el - Element
+ *
+ * @returns Element offset
+ */
+export function getElementOffset(el: HTMLElement): ElementOffset {
+  return {
+    x: el.offsetLeft,
+    y: el.offsetTop
+  }
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch element offset
+ *
+ * @param el - Element
+ *
+ * @returns Element offset observable
+ */
+export function watchElementOffset(
+  el: HTMLElement
+): Observable<ElementOffset> {
+  return fromEvent(window, "resize")
+    .pipe(
+      map(() => getElementOffset(el)),
+      startWith(getElementOffset(el))
+    )
+}

src/assets/javascripts/browser/element/offset/content/index.ts

@@ -0,0 +1,71 @@
+/*
+ * 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,
+  fromEvent,
+  map,
+  merge,
+  startWith
+} from "rxjs"
+
+import { ElementOffset } from "../_"
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve element content offset (= scroll offset)
+ *
+ * @param el - Element
+ *
+ * @returns Element content offset
+ */
+export function getElementContentOffset(el: HTMLElement): ElementOffset {
+  return {
+    x: el.scrollLeft,
+    y: el.scrollTop
+  }
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch element content offset
+ *
+ * @param el - Element
+ *
+ * @returns Element content offset observable
+ */
+export function watchElementContentOffset(
+  el: HTMLElement
+): Observable<ElementOffset> {
+  return merge(
+    fromEvent(el, "scroll"),
+    fromEvent(window, "resize")
+  )
+    .pipe(
+      map(() => getElementContentOffset(el)),
+      startWith(getElementContentOffset(el))
+    )
+}

src/assets/javascripts/browser/element/offset/index.ts

@@ -20,95 +20,5 @@
  * IN THE SOFTWARE.
  */
 
-import {
+export * from "./_"
-  Observable,
+export * from "./content"
-  distinctUntilChanged,
-  fromEvent,
-  map,
-  merge,
-  startWith
-} from "rxjs"
-
-import {
-  getElementContentSize,
-  getElementSize
-} from "../size"
-
-/* ----------------------------------------------------------------------------
- * Types
- * ------------------------------------------------------------------------- */
-
-/**
- * Element offset
- */
-export interface ElementOffset {
-  x: number                            /* Horizontal offset */
-  y: number                            /* Vertical offset */
-}
-
-/* ----------------------------------------------------------------------------
- * Functions
- * ------------------------------------------------------------------------- */
-
-/**
- * Retrieve element offset
- *
- * @param el - Element
- *
- * @returns Element offset
- */
-export function getElementOffset(el: HTMLElement): ElementOffset {
-  return {
-    x: el.scrollLeft,
-    y: el.scrollTop
-  }
-}
-
-/* ------------------------------------------------------------------------- */
-
-/**
- * Watch element offset
- *
- * @param el - Element
- *
- * @returns Element offset observable
- */
-export function watchElementOffset(
-  el: HTMLElement
-): Observable<ElementOffset> {
-  return merge(
-    fromEvent(el, "scroll"),
-    fromEvent(window, "resize")
-  )
-    .pipe(
-      map(() => getElementOffset(el)),
-      startWith(getElementOffset(el))
-    )
-}
-
-/**
- * Watch element threshold
- *
- * This function returns an observable which emits whether the bottom scroll
- * offset of an elements is within a certain threshold.
- *
- * @param el - Element
- * @param threshold - Threshold
- *
- * @returns Element threshold observable
- */
-export function watchElementThreshold(
-  el: HTMLElement, threshold = 16
-): Observable<boolean> {
-  return watchElementOffset(el)
-    .pipe(
-      map(({ y }) => {
-        const visible = getElementSize(el)
-        const content = getElementContentSize(el)
-        return y >= (
-          content.height - visible.height - threshold
-        )
-      }),
-      distinctUntilChanged()
-    )
-}

src/assets/javascripts/browser/element/size/_/index.ts

@@ -0,0 +1,138 @@
+/*
+ * 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 {
+  NEVER,
+  Observable,
+  Subject,
+  defer,
+  filter,
+  finalize,
+  map,
+  of,
+  shareReplay,
+  startWith,
+  switchMap,
+  tap
+} from "rxjs"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Element offset
+ */
+export interface ElementSize {
+  width: number                        /* Element width */
+  height: number                       /* Element height */
+}
+
+/* ----------------------------------------------------------------------------
+ * Data
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Resize observer entry subject
+ */
+const entry$ = new Subject<ResizeObserverEntry>()
+
+/**
+ * Resize observer observable
+ *
+ * This observable will create a `ResizeObserver` on the first subscription
+ * and will automatically terminate it when there are no more subscribers.
+ * It's quite important to centralize observation in a single `ResizeObserver`,
+ * as the performance difference can be quite dramatic, as the link shows.
+ *
+ * @see https://bit.ly/3iIYfEm - Google Groups on performance
+ */
+const observer$ = defer(() => of(
+  new ResizeObserver(entries => {
+    for (const entry of entries)
+      entry$.next(entry)
+  })
+))
+  .pipe(
+    switchMap(observer => NEVER.pipe(startWith(observer))
+      .pipe(
+        finalize(() => observer.disconnect())
+      )
+    ),
+    shareReplay(1)
+  )
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve element size
+ *
+ * @param el - Element
+ *
+ * @returns Element size
+ */
+export function getElementSize(el: HTMLElement): ElementSize {
+  return {
+    width:  el.offsetWidth,
+    height: el.offsetHeight
+  }
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch element size
+ *
+ * This function returns an observable that subscribes to a single internal
+ * instance of `ResizeObserver` upon subscription, and emit resize events until
+ * termination. Note that this function should not be called with the same
+ * element twice, as the first unsubscription will terminate observation.
+ *
+ * Sadly, we can't use the `DOMRect` objects returned by the observer, because
+ * we need the emitted values to be consistent with `getElementSize`, which will
+ * return the used values (rounded) and not actual values (unrounded). Thus, we
+ * use the `offset*` properties. See the linked GitHub issue.
+ *
+ * @see https://bit.ly/3m0k3he - GitHub issue
+ *
+ * @param el - Element
+ *
+ * @returns Element size observable
+ */
+export function watchElementSize(
+  el: HTMLElement
+): Observable<ElementSize> {
+  return observer$
+    .pipe(
+      tap(observer => observer.observe(el)),
+      switchMap(observer => entry$
+        .pipe(
+          filter(({ target }) => target === el),
+          finalize(() => observer.unobserve(el)),
+          map(() => getElementSize(el))
+        )
+      ),
+      startWith(getElementSize(el))
+    )
+}

src/assets/javascripts/browser/element/size/content/index.ts

@@ -0,0 +1,41 @@
+/*
+ * 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 { ElementSize } from "../_"
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve element content size (= scroll width and height)
+ *
+ * @param el - Element
+ *
+ * @returns Element content size
+ */
+export function getElementContentSize(el: HTMLElement): ElementSize {
+  return {
+    width:  el.scrollWidth,
+    height: el.scrollHeight
+  }
+}

src/assets/javascripts/browser/element/size/index.ts

@@ -20,133 +20,5 @@
  * IN THE SOFTWARE.
  */
 
-import {
+export * from "./_"
-  NEVER,
+export * from "./content"
-  Observable,
-  Subject,
-  defer,
-  filter,
-  finalize,
-  map,
-  of,
-  shareReplay,
-  startWith,
-  switchMap,
-  tap
-} from "rxjs"
-
-/* ----------------------------------------------------------------------------
- * Types
- * ------------------------------------------------------------------------- */
-
-/**
- * Element offset
- */
-export interface ElementSize {
-  width: number                        /* Element width */
-  height: number                       /* Element height */
-}
-
-/* ----------------------------------------------------------------------------
- * Data
- * ------------------------------------------------------------------------- */
-
-/**
- * Resize observer entry subject
- */
-const entry$ = new Subject<ResizeObserverEntry>()
-
-/**
- * Resize observer observable
- *
- * This observable will create a `ResizeObserver` on the first subscription
- * and will automatically terminate it when there are no more subscribers.
- * It's quite important to centralize observation in a single `ResizeObserver`,
- * as the performance difference can be quite dramatic, as the link shows.
- *
- * @see https://bit.ly/3iIYfEm - Google Groups on performance
- */
-const observer$ = defer(() => of(
-  new ResizeObserver(entries => {
-    for (const entry of entries)
-      entry$.next(entry)
-  })
-))
-  .pipe(
-    switchMap(resize => NEVER.pipe(startWith(resize))
-      .pipe(
-        finalize(() => resize.disconnect())
-      )
-    ),
-    shareReplay(1)
-  )
-
-/* ----------------------------------------------------------------------------
- * Functions
- * ------------------------------------------------------------------------- */
-
-/**
- * Retrieve element size
- *
- * @param el - Element
- *
- * @returns Element size
- */
-export function getElementSize(el: HTMLElement): ElementSize {
-  return {
-    width:  el.offsetWidth,
-    height: el.offsetHeight
-  }
-}
-
-/**
- * Retrieve element content size, i.e. including overflowing content
- *
- * @param el - Element
- *
- * @returns Element size
- */
-export function getElementContentSize(el: HTMLElement): ElementSize {
-  return {
-    width:  el.scrollWidth,
-    height: el.scrollHeight
-  }
-}
-
-/* ------------------------------------------------------------------------- */
-
-/**
- * Watch element size
- *
- * This function returns an observable that subscribes to a single internal
- * instance of `ResizeObserver` upon subscription, and emit resize events until
- * termination. Note that this function should not be called with the same
- * element twice, as the first unsubscription will terminate observation.
- *
- * Sadly, we can't use the `DOMRect` objects returned by the observer, because
- * we need the emitted values to be consistent with `getElementSize`, which will
- * return the used values (rounded) and not actual values (unrounded). Thus, we
- * use the `offset*` properties. See the linked GitHub issue.
- *
- * @see https://bit.ly/3m0k3he - GitHub issue
- *
- * @param el - Element
- *
- * @returns Element size observable
- */
-export function watchElementSize(
-  el: HTMLElement
-): Observable<ElementSize> {
-  return observer$
-    .pipe(
-      tap(observer => observer.observe(el)),
-      switchMap(observer => entry$
-        .pipe(
-          filter(({ target }) => target === el),
-          finalize(() => observer.unobserve(el)),
-          map(() => getElementSize(el))
-        )
-      ),
-      startWith(getElementSize(el))
-    )
-}

src/assets/javascripts/browser/element/visibility/index.ts

@@ -0,0 +1,131 @@
+/*
+ * 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 {
+  NEVER,
+  Observable,
+  Subject,
+  defer,
+  distinctUntilChanged,
+  filter,
+  finalize,
+  map,
+  of,
+  shareReplay,
+  startWith,
+  switchMap,
+  tap
+} from "rxjs"
+
+import {
+  getElementContentSize,
+  getElementSize,
+  watchElementContentOffset
+} from "~/browser"
+
+/* ----------------------------------------------------------------------------
+ * Data
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Intersection observer entry subject
+ */
+const entry$ = new Subject<IntersectionObserverEntry>()
+
+/**
+ * Intersection observer observable
+ *
+ * This observable will create an `IntersectionObserver` on first subscription
+ * and will automatically terminate it when there are no more subscribers.
+ *
+ * @see https://bit.ly/3iIYfEm - Google Groups on performance
+ */
+const observer$ = defer(() => of(
+  new IntersectionObserver(entries => {
+    for (const entry of entries)
+      entry$.next(entry)
+  }, {
+    threshold: 1
+  })
+))
+  .pipe(
+    switchMap(observer => NEVER.pipe(startWith(observer))
+      .pipe(
+        finalize(() => observer.disconnect())
+      )
+    ),
+    shareReplay(1)
+  )
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch element visibility
+ *
+ * @param el - Element
+ *
+ * @returns Element visibility observable
+ */
+export function watchElementVisibility(
+  el: HTMLElement
+): Observable<boolean> {
+  return observer$
+    .pipe(
+      tap(observer => observer.observe(el)),
+      switchMap(observer => entry$
+        .pipe(
+          filter(({ target }) => target === el),
+          finalize(() => observer.unobserve(el)),
+          map(({ isIntersecting }) => isIntersecting)
+        )
+      )
+    )
+}
+
+/**
+ * Watch element boundary
+ *
+ * This function returns an observable which emits whether the bottom content
+ * boundary (= scroll offset) of an element is within a certain threshold.
+ *
+ * @param el - Element
+ * @param threshold - Threshold
+ *
+ * @returns Element threshold observable
+ */
+export function watchElementBoundary(
+  el: HTMLElement, threshold = 16
+): Observable<boolean> {
+  return watchElementContentOffset(el)
+    .pipe(
+      map(({ y }) => {
+        const visible = getElementSize(el)
+        const content = getElementContentSize(el)
+        return y >= (
+          content.height - visible.height - threshold
+        )
+      }),
+      distinctUntilChanged()
+    )
+}

src/assets/javascripts/browser/location/hash/index.ts

@@ -29,7 +29,7 @@ import {
   startWith
 } from "rxjs"
 
-import { getElement } from "~/browser"
+import { getOptionalElement } from "~/browser"
 import { h } from "~/utilities"
 
 /* ----------------------------------------------------------------------------
@@ -86,7 +86,7 @@ export function watchLocationHash(): Observable<string> {
 export function watchLocationTarget(): Observable<HTMLElement> {
   return watchLocationHash()
     .pipe(
-      map(id => getElement(`[id="${id}"]`)!),
+      map(id => getOptionalElement(`[id="${id}"]`)!),
       filter(el => typeof el !== "undefined")
     )
 }

src/assets/javascripts/browser/toggle/index.ts

@@ -27,7 +27,7 @@ import {
   startWith
 } from "rxjs"
 
-import { getElementOrThrow } from "../element"
+import { getElement } from "../element"
 
 /* ----------------------------------------------------------------------------
  * Types
@@ -48,8 +48,8 @@ export type Toggle =
  * Toggle map
  */
 const toggles: Record<Toggle, HTMLInputElement> = {
-  drawer: getElementOrThrow("[data-md-toggle=drawer]"),
+  drawer: getElement("[data-md-toggle=drawer]"),
-  search: getElementOrThrow("[data-md-toggle=search]")
+  search: getElement("[data-md-toggle=search]")
 }
 
 /* ----------------------------------------------------------------------------

src/assets/javascripts/browser/viewport/_/index.ts

@@ -30,6 +30,7 @@ import {
 
 import { Header } from "~/components"
 
+import { getElementOffset } from "../../element"
 import {
   ViewportOffset,
   watchViewportOffset
@@ -102,10 +103,7 @@ export function watchViewportAt(
   /* Compute element offset */
   const offset$ = combineLatest([size$, header$])
     .pipe(
-      map((): ViewportOffset => ({
+      map(() => getElementOffset(el))
-        x: el.offsetLeft,
-        y: el.offsetTop
-      }))
     )
 
   /* Compute relative viewport, return hot observable */

src/assets/javascripts/browser/viewport/offset/index.ts

@@ -54,8 +54,8 @@ export interface ViewportOffset {
  */
 export function getViewportOffset(): ViewportOffset {
   return {
-    x: Math.max(0, pageXOffset),
+    x: Math.max(0, scrollX),
-    y: Math.max(0, pageYOffset)
+    y: Math.max(0, scrollY)
   }
 }
 

src/assets/javascripts/bundle.ts

@@ -37,7 +37,7 @@ import {
 import { configuration, feature } from "./_"
 import {
   at,
-  getElement,
+  getOptionalElement,
   requestJSON,
   setToggle,
   watchDocument,
@@ -96,6 +96,7 @@ const keyboard$ = watchKeyboard()
 const viewport$ = watchViewport()
 const tablet$   = watchMedia("(min-width: 960px)")
 const screen$   = watchMedia("(min-width: 1220px)")
+const hover$    = watchMedia("(hover)")
 const print$    = watchPrint()
 
 /* Retrieve search index, if search is enabled */
@@ -139,7 +140,7 @@ keyboard$
         /* Go to previous page */
         case "p":
         case ",":
-          const prev = getElement("[href][rel=prev]")
+          const prev = getOptionalElement("[href][rel=prev]")
           if (typeof prev !== "undefined")
             prev.click()
           break
@@ -147,7 +148,7 @@ keyboard$
         /* Go to next page */
         case "n":
         case ".":
-          const next = getElement("[href][rel=next]")
+          const next = getOptionalElement("[href][rel=next]")
           if (typeof next !== "undefined")
             next.click()
           break
@@ -197,7 +198,7 @@ const content$ = defer(() => merge(
 
   /* Content */
   ...getComponentElements("content")
-    .map(el => mountContent(el, { target$, viewport$, print$ })),
+    .map(el => mountContent(el, { target$, viewport$, hover$, print$ })),
 
   /* Search highlighting */
   ...getComponentElements("content")
@@ -250,8 +251,9 @@ window.location$  = location$          /* Location subject */
 window.target$    = target$            /* Location target observable */
 window.keyboard$  = keyboard$          /* Keyboard observable */
 window.viewport$  = viewport$          /* Viewport observable */
-window.tablet$    = tablet$            /* Tablet observable */
+window.tablet$    = tablet$            /* Media tablet observable */
-window.screen$    = screen$            /* Screen observable */
+window.screen$    = screen$            /* Media screen observable */
-window.print$     = print$             /* Print observable */
+window.hover$     = hover$             /* Media hover observable */
+window.print$     = print$             /* Media print observable */
 window.alert$     = alert$             /* Alert subject */
 window.component$ = component$         /* Component observable */

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

@@ -20,7 +20,7 @@
  * IN THE SOFTWARE.
  */
 
-import { getElementOrThrow, getElements } from "~/browser"
+import { getElement, getElements } from "~/browser"
 
 /* ----------------------------------------------------------------------------
  * Types
@@ -114,7 +114,7 @@ interface ComponentTypeMap {
 export function getComponentElement<T extends ComponentType>(
   type: T, node: ParentNode = document
 ): ComponentTypeMap[T] {
-  return getElementOrThrow(`[data-md-component=${type}]`, node)
+  return getElement(`[data-md-component=${type}]`, node)
 }
 
 /**

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

@@ -53,7 +53,8 @@ export type Content =
 interface MountOptions {
   target$: Observable<HTMLElement>     /* Location target observable */
   viewport$: Observable<Viewport>      /* Viewport observable */
-  print$: Observable<boolean>          /* Print observable */
+  hover$: Observable<boolean>          /* Media hover observable */
+  print$: Observable<boolean>          /* Media print observable */
 }
 
 /* ----------------------------------------------------------------------------
@@ -72,13 +73,13 @@ interface MountOptions {
  * @returns Content component observable
  */
 export function mountContent(
-  el: HTMLElement, { target$, viewport$, print$ }: MountOptions
+  el: HTMLElement, { target$, viewport$, hover$, print$ }: MountOptions
 ): Observable<Component<Content>> {
   return merge(
 
     /* Code blocks */
     ...getElements("pre > code", el)
-      .map(child => mountCodeBlock(child, { viewport$, print$ })),
+      .map(child => mountCodeBlock(child, { viewport$, hover$, print$ })),
 
     /* Data tables */
     ...getElements("table:not([class])", el)

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

@@ -41,14 +41,17 @@ import {
 } from "rxjs"
 
 import { feature } from "~/_"
-import { resetFocusable, setFocusable } from "~/actions"
+import {
+  resetFocusable,
+  setFocusable
+} from "~/actions"
 import {
   Viewport,
   getElement,
   getElementContentSize,
-  getElementOrThrow,
   getElementSize,
   getElements,
+  getOptionalElement,
   watchMedia
 } from "~/browser"
 import {
@@ -174,7 +177,7 @@ export function watchCodeBlock(
           container.insertAdjacentElement("afterend", list)
           for (const annotation of annotations) {
             const id = parseInt(annotation.getAttribute("data-index")!, 10)
-            const typeset = getElement(":scope .md-typeset", annotation)!
+            const typeset = getOptionalElement(":scope .md-typeset", annotation)!
             items[id - 1].append(...Array.from(typeset.childNodes))
           }
         } else {
@@ -182,7 +185,7 @@ export function watchCodeBlock(
           for (const annotation of annotations) {
             const id = parseInt(annotation.getAttribute("data-index")!, 10)
             const nodes = items[id - 1].childNodes
-            getElementOrThrow(":scope .md-typeset", annotation)
+            getElement(":scope .md-typeset", annotation)
               .append(...Array.from(nodes))
           }
         }
@@ -239,7 +242,7 @@ export function mountCodeBlock(
       take(1),
       takeWhile(({ annotations }) => !!annotations?.length),
       map(({ annotations }) => annotations!
-        .map(annotation => getElementOrThrow(".md-tooltip", annotation))
+        .map(annotation => getElement(".md-tooltip", annotation))
       ),
       combineLatestWith(viewport$
         .pipe(

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

@@ -54,7 +54,7 @@ export interface Details {
  */
 interface WatchOptions {
   target$: Observable<HTMLElement>     /* Location target observable */
-  print$: Observable<boolean>          /* Print observable */
+  print$: Observable<boolean>          /* Media print observable */
 }
 
 /**
@@ -62,7 +62,7 @@ interface WatchOptions {
  */
 interface MountOptions {
   target$: Observable<HTMLElement>     /* Location target observable */
-  print$: Observable<boolean>          /* Print observable */
+  print$: Observable<boolean>          /* Media print observable */
 }
 
 /* ----------------------------------------------------------------------------

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

@@ -22,7 +22,6 @@
 
 import { Observable, of } from "rxjs"
 
-import { replaceElement } from "~/browser"
 import { renderTable } from "~/templates"
 import { h } from "~/utilities"
 
@@ -63,8 +62,8 @@ const sentinel = h("table")
 export function mountDataTable(
   el: HTMLElement
 ): Observable<Component<DataTable>> {
-  replaceElement(el, sentinel)
+  el.replaceWith(sentinel)
-  replaceElement(sentinel, renderTable(el))
+  sentinel.replaceWith(renderTable(el))
 
   /* Create and return component */
   return of({ ref: el })

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

@@ -21,7 +21,6 @@
  */
 
 import {
-  NEVER,
   Observable,
   Subject,
   finalize,
@@ -33,7 +32,7 @@ import {
 } from "rxjs"
 
 import {
-  getElementOrThrow,
+  getElement,
   getElements
 } from "~/browser"
 
@@ -64,17 +63,14 @@ export interface ContentTabs {
 export function watchContentTabs(
   el: HTMLElement
 ): Observable<ContentTabs> {
-  if (!el.classList.contains("tabbed-alternate"))
+  return merge(...getElements(":scope > input", el)
-    return NEVER
+    .map(input => fromEvent(input, "change").pipe(mapTo(input.id)))
-  else
+  )
-    return merge(...getElements(":scope > input", el)
+    .pipe(
-      .map(input => fromEvent(input, "change").pipe(mapTo(input.id)))
+      map(id => ({
+        active: getElement<HTMLLabelElement>(`label[for=${id}]`)
+      }))
     )
-      .pipe(
-        map(id => ({
-          active: getElementOrThrow<HTMLLabelElement>(`label[for=${id}]`)
-        }))
-      )
 }
 
 /**

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

@@ -40,7 +40,10 @@ import {
 } from "rxjs"
 
 import { feature } from "~/_"
-import { resetHeaderState, setHeaderState } from "~/actions"
+import {
+  resetHeaderState,
+  setHeaderState
+} from "~/actions"
 import {
   Viewport,
   watchElementSize,

src/assets/javascripts/components/header/title/index.ts

@@ -38,8 +38,8 @@ import {
 } from "~/actions"
 import {
   Viewport,
-  getElement,
   getElementSize,
+  getOptionalElement,
   watchViewportAt
 } from "~/browser"
 
@@ -131,7 +131,7 @@ export function mountHeaderTitle(
       })
 
   /* Obtain headline, if any */
-  const headline = getElement<HTMLHeadingElement>("article h1")
+  const headline = getOptionalElement<HTMLHeadingElement>("article h1")
   if (typeof headline === "undefined")
     return NEVER
 

src/assets/javascripts/components/main/index.ts

@@ -29,7 +29,10 @@ import {
   switchMap
 } from "rxjs"
 
-import { Viewport, watchElementSize } from "~/browser"
+import {
+  Viewport,
+  watchElementSize
+} from "~/browser"
 
 import { Header } from "../header"
 

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

@@ -53,10 +53,19 @@ import {
   getComponentElement,
   getComponentElements
 } from "../../_"
-import { SearchQuery, mountSearchQuery } from "../query"
+import {
+  SearchQuery,
+  mountSearchQuery
+} from "../query"
 import { mountSearchResult } from "../result"
-import { SearchShare, mountSearchShare } from "../share"
+import {
-import { SearchSuggest, mountSearchSuggest } from "../suggest"
+  SearchShare,
+  mountSearchShare
+} from "../share"
+import {
+  SearchSuggest,
+  mountSearchSuggest
+} from "../suggest"
 
 /* ----------------------------------------------------------------------------
  * Types

src/assets/javascripts/components/search/result/index.ts

@@ -46,8 +46,8 @@ import {
   setSearchResultMeta
 } from "~/actions"
 import {
-  getElementOrThrow,
+  getElement,
-  watchElementThreshold
+  watchElementBoundary
 } from "~/browser"
 import {
   SearchResult,
@@ -91,14 +91,14 @@ export function mountSearchResult(
   el: HTMLElement, { rx$ }: SearchWorker, { query$ }: MountOptions
 ): Observable<Component<SearchResult>> {
   const internal$ = new Subject<SearchResult>()
-  const boundary$ = watchElementThreshold(el.parentElement!)
+  const boundary$ = watchElementBoundary(el.parentElement!)
     .pipe(
       filter(Boolean)
     )
 
   /* Retrieve nested components */
-  const meta = getElementOrThrow(":scope > :first-child", el)
+  const meta = getElement(":scope > :first-child", el)
-  const list = getElementOrThrow(":scope > :last-child", el)
+  const list = getElement(":scope > :last-child", el)
 
   /* Wait until search is ready */
   const ready$ = rx$

src/assets/javascripts/components/sidebar/index.ts

@@ -98,9 +98,10 @@ interface MountOptions {
 export function watchSidebar(
   el: HTMLElement, { viewport$, main$ }: WatchOptions
 ): Observable<Sidebar> {
+  const parent = el.parentElement!
   const adjust =
-    el.parentElement!.offsetTop -
+    parent.offsetTop -
-    el.parentElement!.parentElement!.offsetTop
+    parent.parentElement!.offsetTop
 
   /* Compute the sidebar's available height and if it should be locked */
   return combineLatest([main$, viewport$])

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

@@ -34,11 +34,17 @@ import {
   tap
 } from "rxjs"
 
-import { setSourceFacts, setSourceState } from "~/actions"
+import {
+  setSourceFacts,
+  setSourceState
+} from "~/actions"
 import { renderSourceFacts } from "~/templates"
 
 import { Component } from "../../_"
-import { SourceFacts, fetchSourceFacts } from "../facts"
+import {
+  SourceFacts,
+  fetchSourceFacts
+} from "../facts"
 
 /* ----------------------------------------------------------------------------
  * Types

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

@@ -34,7 +34,10 @@ import {
 } from "rxjs"
 
 import { feature } from "~/_"
-import { resetTabsState, setTabsState } from "~/actions"
+import {
+  resetTabsState,
+  setTabsState
+} from "~/actions"
 import {
   Viewport,
   watchElementSize,

src/assets/javascripts/components/toc/index.ts

@@ -48,9 +48,9 @@ import {
 } from "~/actions"
 import {
   Viewport,
-  getElement,
   getElements,
   getLocation,
+  getOptionalElement,
   watchElementSize
 } from "~/browser"
 
@@ -122,7 +122,7 @@ export function watchTableOfContents(
   const anchors = getElements<HTMLAnchorElement>("[href^=\\#]", el)
   for (const anchor of anchors) {
     const id = decodeURIComponent(anchor.hash.substring(1))
-    const target = getElement(`[id="${id}"]`)
+    const target = getOptionalElement(`[id="${id}"]`)
     if (typeof target !== "undefined")
       table.set(anchor, target)
   }

src/assets/javascripts/components/top/index.ts

@@ -43,7 +43,10 @@ import {
   setBackToTopState,
   setFocusable
 } from "~/actions"
-import { Viewport, setElementFocus } from "~/browser"
+import {
+  Viewport,
+  setElementFocus
+} from "~/browser"
 
 import { Component } from "../_"
 import { Header } from "../header"

src/assets/javascripts/integrations/clipboard/index.ts

@@ -25,7 +25,7 @@ import { Observable, Subject } from "rxjs"
 
 import { translation } from "~/_"
 import {
-  getElementOrThrow,
+  getElement,
   getElements
 } from "~/browser"
 
@@ -85,7 +85,7 @@ export function setupClipboardJS(
       new ClipboardJS("[data-clipboard-target], [data-clipboard-text]", {
         text: el => (
           el.getAttribute("data-clipboard-text")! ||
-          extract(getElementOrThrow(
+          extract(getElement(
             el.getAttribute("data-clipboard-target")!
           ))
         )

src/assets/javascripts/integrations/instant/index.ts

@@ -47,9 +47,8 @@ import { configuration, feature } from "~/_"
 import {
   Viewport,
   ViewportOffset,
-  getElement,
   getElements,
-  replaceElement,
+  getOptionalElement,
   request,
   requestXML,
   setLocation,
@@ -166,7 +165,7 @@ export function setupInstantLoading(
   }
 
   /* Hack: ensure absolute favicon link to omit 404s when switching */
-  const favicon = getElement<HTMLLinkElement>("link[rel=icon]")
+  const favicon = getOptionalElement<HTMLLinkElement>("link[rel=icon]")
   if (typeof favicon !== "undefined")
     favicon.href = favicon.href
 
@@ -286,13 +285,13 @@ export function setupInstantLoading(
             ? ["[data-md-component=tabs]"]
             : []
         ]) {
-          const source = getElement(selector)
+          const source = getOptionalElement(selector)
-          const target = getElement(selector, replacement)
+          const target = getOptionalElement(selector, replacement)
           if (
             typeof source !== "undefined" &&
             typeof target !== "undefined"
           ) {
-            replaceElement(source, target)
+            source.replaceWith(target)
           }
         }
       })
@@ -308,7 +307,7 @@ export function setupInstantLoading(
         if (el.src) {
           for (const name of el.getAttributeNames())
             script.setAttribute(name, el.getAttribute(name)!)
-          replaceElement(el, script)
+          el.replaceWith(script)
 
           /* Complete when script is loaded */
           return new Observable(observer => {
@@ -318,7 +317,7 @@ export function setupInstantLoading(
         /* Complete immediately */
         } else {
           script.textContent = el.textContent
-          replaceElement(el, script)
+          el.replaceWith(script)
           return EMPTY
         }
       })

src/assets/javascripts/integrations/version/index.ts

@@ -24,7 +24,7 @@ import { combineLatest, map } from "rxjs"
 
 import { configuration } from "~/_"
 import {
-  getElementOrThrow,
+  getElement,
   requestJSON
 } from "~/browser"
 import { getComponentElements } from "~/components"
@@ -60,7 +60,7 @@ export function setupVersionSelector(): void {
   /* Render version selector and warning */
   combineLatest([versions$, current$])
     .subscribe(([versions, current]) => {
-      const topic = getElementOrThrow(".md-header__topic")
+      const topic = getElement(".md-header__topic")
       topic.appendChild(renderVersionSelector(versions, current))
 
       /* Check if version state was already determined */

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

@@ -43,7 +43,7 @@ import { getElements } from "~/browser"
  */
 interface PatchOptions {
   document$: Observable<Document>      /* Document observable */
-  tablet$: Observable<boolean>         /* Tablet breakpoint observable */
+  tablet$: Observable<boolean>         /* Media tablet observable */
 }
 
 /* ----------------------------------------------------------------------------

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

@@ -32,8 +32,14 @@ import {
   withLatestFrom
 } from "rxjs"
 
-import { resetScrollLock, setScrollLock } from "~/actions"
+import {
-import { Viewport, watchToggle } from "~/browser"
+  resetScrollLock,
+  setScrollLock
+} from "~/actions"
+import {
+  Viewport,
+  watchToggle
+} from "~/browser"
 
 /* ----------------------------------------------------------------------------
  * Helper types
@@ -44,7 +50,7 @@ import { Viewport, watchToggle } from "~/browser"
  */
 interface PatchOptions {
   viewport$: Observable<Viewport>      /* Viewport observable */
-  tablet$: Observable<boolean>         /* Tablet breakpoint observable */
+  tablet$: Observable<boolean>         /* Media tablet observable */
 }
 
 /* ----------------------------------------------------------------------------

src/assets/javascripts/templates/code/index.tsx

@@ -27,7 +27,7 @@ import { h } from "~/utilities"
  * ------------------------------------------------------------------------- */
 
 /**
- * Render a 'copy-to-clipboard' button
+ * Render a a code annotation
  *
  * @param id - Unique identifier
  * @param content - Annotation content

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

@@ -20,7 +20,7 @@
  * IN THE SOFTWARE.
  */
 
-import { getElementOrThrow, getElements } from "~/browser"
+import { getElement, getElements } from "~/browser"
 
 /* ----------------------------------------------------------------------------
  * Types
@@ -84,7 +84,7 @@ interface ComponentTypeMap {
 export function getComponentElement<T extends ComponentType>(
   type: T, node: ParentNode = document
 ): ComponentTypeMap[T] {
-  return getElementOrThrow(`[data-mdx-component=${type}]`, node)
+  return getElement(`[data-mdx-component=${type}]`, node)
 }
 
 /**

src/overrides/assets/javascripts/components/iconsearch/result/index.ts

@@ -47,8 +47,8 @@ import {
   setSearchResultMeta
 } from "~/actions"
 import {
-  getElementOrThrow,
+  getElement,
-  watchElementThreshold
+  watchElementBoundary
 } from "~/browser"
 
 import { Icon, renderIconSearchResult } from "_/templates"
@@ -147,13 +147,13 @@ export function mountIconSearchResult(
   el: HTMLElement, { index$, query$ }: MountOptions
 ): Observable<Component<IconSearchResult, HTMLElement>> {
   const internal$ = new Subject<IconSearchResult>()
-  const boundary$ = watchElementThreshold(el)
+  const boundary$ = watchElementBoundary(el)
     .pipe(
       filter(Boolean)
     )
 
   /* Update search result metadata */
-  const meta = getElementOrThrow(":scope > :first-child", el)
+  const meta = getElement(":scope > :first-child", el)
   internal$
     .pipe(
       observeOn(animationFrameScheduler),
@@ -167,7 +167,7 @@ export function mountIconSearchResult(
       })
 
   /* Update icon search result list */
-  const list = getElementOrThrow(":scope > :last-child", el)
+  const list = getElement(":scope > :last-child", el)
   internal$
     .pipe(
       observeOn(animationFrameScheduler),

src/overrides/assets/javascripts/components/sponsorship/index.ts

@@ -22,7 +22,7 @@
 
 import { Observable, map } from "rxjs"
 
-import { getElementOrThrow, requestJSON } from "~/browser"
+import { getElement, requestJSON } from "~/browser"
 
 import { renderPrivateSponsor, renderPublicSponsor } from "_/templates"
 
@@ -121,7 +121,7 @@ export function mountSponsorship(
     el.removeAttribute("hidden")
 
     /* Render public sponsors with avatar and links */
-    const list = getElementOrThrow(":scope > :first-child", el)
+    const list = getElement(":scope > :first-child", el)
     for (const sponsor of sponsorship.sponsors)
       if (sponsor.type === "public")
         list.appendChild(renderPublicSponsor(sponsor.user))

tools/build/transform/index.ts

@@ -182,6 +182,7 @@ export function transformScript(
           map: Buffer.from(data, "base64")
         })
       }),
+      catchError(() => NEVER),
       switchMap(({ js, map }) => {
         const file = digest(options.to, js)
         return concat(

typings/_/index.d.ts

@@ -106,9 +106,10 @@ declare global {
   var target$: Observable<HTMLElement> /* Location target observable */
   var keyboard$: Observable<Keyboard>  /* Keyboard observable */
   var viewport$: Observable<Viewport>  /* Viewport obsevable */
-  var tablet$: Observable<boolean>     /* Tablet breakpoint observable */
+  var tablet$: Observable<boolean>     /* Media tablet observable */
-  var screen$: Observable<boolean>     /* Screen breakpoint observable */
+  var screen$: Observable<boolean>     /* Media screen observable */
-  var print$: Observable<boolean>      /* Print observable */
+  var hover$: Observable<boolean>      /* Media hover observable */
+  var print$: Observable<boolean>      /* Media print observable */
   var alert$: Subject<string>          /* Alert subject */
   var component$: Observable<Component>/* Component observable */
 }