Unified components and observable structure

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

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+/*
+ * Copyright (c) 2016-2020 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, fromEvent, merge } from "rxjs"
+import { mapTo, shareReplay } from "rxjs/operators"
+
+import { watchDocumentSwitch } from "../switch"
+
+/* ----------------------------------------------------------------------------
+ * Helper types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch options
+ */
+interface WatchOptions {
+  location$?: Observable<URL>          /* Location observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch document
+ *
+ * If the location observable is passed, instant loading will be enabled which
+ * means that new values will be emitted every time the location changes.
+ *
+ * @return Document observable
+ */
+export function watchDocument(
+  { location$ }: WatchOptions = {}
+): Observable<Document> {
+  return merge(
+    fromEvent(document, "DOMContentLoaded")
+      .pipe(
+        mapTo(document)
+      ),
+    typeof location$ !== "undefined"
+      ? watchDocumentSwitch({ location$ })
+      : NEVER
+  )
+    .pipe(
+      shareReplay(1)
+    )
+}

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

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+/*
+ * Copyright (c) 2016-2020 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.
+ */
+
+export * from "./_"
+export * from "./switch"

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

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+/*
+ * Copyright (c) 2016-2020 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 } from "rxjs"
+import { ajax } from "rxjs/ajax"
+import {
+  catchError,
+  distinctUntilKeyChanged,
+  pluck,
+  share,
+  skip,
+  switchMap
+} from "rxjs/operators"
+
+import { setLocation } from "../../location"
+
+/* ----------------------------------------------------------------------------
+ * Helper types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch options
+ */
+interface WatchOptions {
+  location$: Observable<URL>           /* Location observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch document switch
+ *
+ * This function returns an observables that fetches a document if the provided
+ * location observable emits a new value (i.e. URL). If the emitted URL points
+ * to the same page, the request is effectively ignored (i.e. when only the
+ * fragment identifier changes).
+ *
+ * In case the request fails, the location change is dispatched regularly.
+ *
+ * @param options - Options
+ *
+ * @return Document observable
+ */
+export function watchDocumentSwitch(
+  { location$ }: WatchOptions
+): Observable<Document> {
+  return location$
+    .pipe(
+      distinctUntilKeyChanged("pathname"),
+      skip(1),
+
+      /* Fetch document */
+      switchMap(url => ajax({
+        url: url.href,
+        responseType: "document",
+        withCredentials: true
+      })
+        .pipe<Document, Document>(
+          pluck("response"),
+          catchError(() => {
+            setLocation(url)
+            return NEVER
+          })
+        )
+      ),
+      share()
+    )
+}

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

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2016-2020 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.
+ */
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve an element matching the query selector
+ *
+ * @template T - Element type
+ *
+ * @param selector - Query selector
+ * @param node - Node of reference
+ *
+ * @return Element or nothing
+ */
+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
+ *
+ * @return Element
+ */
+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 el
+}
+
+/**
+ * Retrieve the currently active element
+ *
+ * @return Element or nothing
+ */
+export function getActiveElement(): HTMLElement | undefined {
+  return document.activeElement instanceof HTMLElement
+    ? document.activeElement
+    : undefined
+}
+
+/**
+ * Retrieve all elements matching the query selector
+ *
+ * @template T - Element type
+ *
+ * @param selector - Query selector
+ * @param node - Node of reference
+ *
+ * @return Elements
+ */
+export function getElements<T extends HTMLElement>(
+  selector: string, node: ParentNode = document
+): T[] {
+  return Array.from(node.querySelectorAll<T>(selector))
+}

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

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2016-2020 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, merge } from "rxjs"
+import { mapTo, shareReplay, startWith } from "rxjs/operators"
+
+import { getActiveElement } from "../_"
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Set element focus
+ *
+ * @param el - Element
+ * @param value - Whether the element should be focused
+ */
+export function setElementFocus(
+el: HTMLElement, value: boolean = true
+): void {
+  if (value)
+    el.focus()
+  else
+    el.blur()
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch element focus
+ *
+ * @param el - Element
+ *
+ * @return Element focus observable
+ */
+export function watchElementFocus(
+  el: HTMLElement
+): Observable<boolean> {
+  const focus$ = fromEvent(el, "focus")
+  const blur$  = fromEvent(el, "blur")
+
+  /* Map events to boolean state */
+  return merge(
+    focus$.pipe(mapTo(true)),
+    blur$.pipe(mapTo(false))
+  )
+    .pipe(
+      startWith(el === getActiveElement()),
+      shareReplay(1)
+    )
+}

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

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2016-2020 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.
+ */
+
+export * from "./_"
+export * from "./focus"
+export * from "./offset"
+export * from "./select"

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

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2016-2020 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, merge } from "rxjs"
+import { map, shareReplay, startWith } from "rxjs/operators"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Element offset
+ */
+export interface ElementOffset {
+  x: number                            /* Horizontal offset */
+  y: number                            /* Vertical offset */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve element offset
+ *
+ * @param el - Element
+ *
+ * @return Element offset
+ */
+export function getElementOffset(el: HTMLElement): ElementOffset {
+  return {
+    x: el.scrollLeft,
+    y: el.scrollTop
+  }
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch element offset
+ *
+ * @param el - Element
+ *
+ * @return Element offset observable
+ */
+export function watchElementOffset(
+  el: HTMLElement
+): Observable<ElementOffset> {
+  return merge(
+    fromEvent<UIEvent>(el, "scroll"),
+    fromEvent<UIEvent>(window, "resize")
+  )
+    .pipe(
+      map(() => getElementOffset(el)),
+      startWith(getElementOffset(el)),
+      shareReplay(1)
+    )
+}

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

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+/*
+ * Copyright (c) 2016-2020 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.
+ */
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Set element text selection
+ *
+ * @param el - Element
+ */
+export function setElementSelection(
+  el: HTMLElement
+): void {
+  if (el instanceof HTMLInputElement)
+    el.select()
+  else
+    throw new Error("Not implemented")
+}

src/assets/javascripts/browser/index.ts

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2016-2020 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.
+ */
+
+export * from "./document"
+export * from "./element"
+export * from "./keyboard"
+export * from "./location"
+export * from "./media"
+export * from "./toggle"
+export * from "./viewport"
+export * from "./worker"

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

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2016-2020 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 } from "rxjs"
+import { filter, map, share } from "rxjs/operators"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Key
+ */
+export interface Key {
+  type: string                         /* Key type */
+  claim(): void                        /* Key claim */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Check whether an element may receive keyboard input
+ *
+ * @param el - Element
+ *
+ * @return Test result
+ */
+export function isSusceptibleToKeyboard(el: HTMLElement): boolean {
+  switch (el.tagName) {
+
+    /* Form elements */
+    case "INPUT":
+    case "SELECT":
+    case "TEXTAREA":
+      return true
+
+    /* Everything else */
+    default:
+      return el.isContentEditable
+  }
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch keyboard
+ *
+ * @return Keyboard observable
+ */
+export function watchKeyboard(): Observable<Key> {
+  return fromEvent<KeyboardEvent>(window, "keydown")
+    .pipe(
+      filter(ev => !(ev.metaKey || ev.ctrlKey)),
+      map(ev => ({
+        type: ev.key,
+        claim() {
+          ev.preventDefault()
+          ev.stopPropagation()
+        }
+      })),
+      share()
+    )
+}

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

@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2016-2020 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 { BehaviorSubject } from "rxjs"
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve location
+ *
+ * This function will return a `URL` object (and not `Location`) in order to
+ * normalize typings across the application. Furthermore, locations need to be
+ * tracked without setting them and `Location` is a singleton which represents
+ * the current location.
+ *
+ * @return URL
+ */
+export function getLocation(): URL {
+  return new URL(location.href)
+}
+
+/**
+ * Set location
+ *
+ * @param url - URL to change to
+ */
+export function setLocation(url: URL): void {
+  location.href = url.href
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Check whether a URL is an internal link or a file (except `.html`)
+ *
+ * @param url - URL or HTML anchor element
+ * @param ref - Reference URL
+ *
+ * @return Test result
+ */
+export function isLocationInternal(
+  url: URL | HTMLAnchorElement,
+  ref: URL | Location = location
+): boolean {
+  return url.host === ref.host
+      && /^(?:\/[\w-]+)*(?:\/?|\.html)$/i.test(url.pathname)
+}
+
+/**
+ * Check whether a URL is an anchor link on the current page
+ *
+ * @param url - URL or HTML anchor element
+ * @param ref - Reference URL
+ *
+ * @return Test result
+ */
+export function isLocationAnchor(
+  url: URL | HTMLAnchorElement,
+  ref: URL | Location = location
+): boolean {
+  return url.pathname === ref.pathname
+      && url.hash.length > 0
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch location
+ *
+ * @return Location subject
+ */
+export function watchLocation(): BehaviorSubject<URL> {
+  return new BehaviorSubject<URL>(getLocation())
+}

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

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2016-2020 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 } from "rxjs"
+import { filter, map, share, startWith } from "rxjs/operators"
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve location hash
+ *
+ * @return Location hash
+ */
+export function getLocationHash(): string {
+  return location.hash.substring(1)
+}
+
+/**
+ * Set location hash
+ *
+ * Setting a new fragment identifier via `location.hash` will have no effect
+ * if the value doesn't change. However, when a new fragment identifier is set,
+ * we want the browser to target the respective element at all times, which is
+ * why we use this dirty little trick.
+ *
+ * @param hash - Location hash
+ */
+export function setLocationHash(hash: string): void {
+  const el = document.createElement("a")
+  el.href = hash
+  el.click()
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch location hash
+ *
+ * @return Location hash observable
+ */
+export function watchLocationHash(): Observable<string> {
+  return fromEvent<HashChangeEvent>(window, "hashchange")
+    .pipe(
+      map(getLocationHash),
+      startWith(getLocationHash()),
+      filter(hash => hash.length > 0),
+      share()
+    )
+}

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

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2016-2020 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.
+ */
+
+export * from "./_"
+export * from "./hash"

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

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2016-2020 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, fromEventPattern } from "rxjs"
+import { shareReplay, startWith } from "rxjs/operators"
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch media query
+ *
+ * @param query - Media query
+ *
+ * @return Media observable
+ */
+export function watchMedia(query: string): Observable<boolean> {
+  const media = matchMedia(query)
+  return fromEventPattern<boolean>(next =>
+    media.addListener(() => next(media.matches))
+  )
+    .pipe(
+      startWith(media.matches),
+      shareReplay(1)
+    )
+}

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

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2016-2020 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 } from "rxjs"
+import { map, startWith } from "rxjs/operators"
+
+import { getElementOrThrow } from "../element"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Toggle
+ */
+export type Toggle =
+  | "drawer"                           /* Toggle for drawer */
+  | "search"                           /* Toggle for search */
+
+/* ----------------------------------------------------------------------------
+ * Data
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Toggle map
+ */
+const toggles: Record<Toggle, HTMLInputElement> = {
+  drawer: getElementOrThrow(`[data-md-toggle=drawer]`),
+  search: getElementOrThrow(`[data-md-toggle=search]`)
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve the value of a toggle
+ *
+ * @param name - Toggle
+ *
+ * @return Toggle value
+ */
+export function getToggle(name: Toggle): boolean {
+  return toggles[name].checked
+}
+
+/**
+ * Set toggle
+ *
+ * Simulating a click event seems to be the most cross-browser compatible way
+ * of changing the value while also emitting a `change` event. Before, Material
+ * used `CustomEvent` to programmatically change the value of a toggle, but this
+ * is a much simpler and cleaner solution which doesn't require a polyfill.
+ *
+ * @param name - Toggle
+ * @param value - Toggle value
+ */
+export function setToggle(name: Toggle, value: boolean): void {
+  if (toggles[name].checked !== value)
+    toggles[name].click()
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch toggle
+ *
+ * @param name - Toggle
+ *
+ * @return Toggle value observable
+ */
+export function watchToggle(name: Toggle): Observable<boolean> {
+  const el = toggles[name]
+  return fromEvent(el, "change")
+    .pipe(
+      map(() => el.checked),
+      startWith(el.checked)
+    )
+}

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

@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2016-2020 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, combineLatest } from "rxjs"
+import {
+  distinctUntilKeyChanged,
+  map,
+  shareReplay
+} from "rxjs/operators"
+
+import { Header } from "components"
+
+import {
+  ViewportOffset,
+  watchViewportOffset
+} from "../offset"
+import {
+  ViewportSize,
+  watchViewportSize
+} from "../size"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Viewport
+ */
+export interface Viewport {
+  offset: ViewportOffset               /* Viewport offset */
+  size: ViewportSize                   /* Viewport size */
+}
+
+/* ----------------------------------------------------------------------------
+ * Helper types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch at options
+ */
+interface WatchAtOptions {
+  header$: Observable<Header>          /* Header observable */
+  viewport$: Observable<Viewport>      /* Viewport observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch viewport
+ *
+ * @return Viewport observable
+ */
+export function watchViewport(): Observable<Viewport> {
+  return combineLatest([
+    watchViewportOffset(),
+    watchViewportSize()
+  ])
+    .pipe(
+      map(([offset, size]) => ({ offset, size })),
+      shareReplay(1)
+    )
+}
+
+/**
+ * Watch viewport relative to element
+ *
+ * @param el - Element
+ * @param options - Options
+ *
+ * @return Viewport observable
+ */
+export function watchViewportAt(
+  el: HTMLElement, { header$, viewport$ }: WatchAtOptions
+): Observable<Viewport> {
+  const offset$ = viewport$
+    .pipe(
+      distinctUntilKeyChanged("size"),
+      map((): ViewportOffset => ({
+        x: el.offsetLeft,
+        y: el.offsetTop
+      }))
+    )
+
+  /* Compute relative viewport, return hot observable */
+  return combineLatest([header$, viewport$, offset$])
+    .pipe(
+      map(([{ height }, { offset, size }, { x, y }]) => ({
+        offset: {
+          x: offset.x - x,
+          y: offset.y - y + height
+        },
+        size
+      })),
+      shareReplay(1)
+    )
+}

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

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2016-2020 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.
+ */
+
+export * from "./_"
+export * from "./offset"
+export * from "./size"

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

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2016-2020 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, merge } from "rxjs"
+import { map, startWith } from "rxjs/operators"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Viewport offset
+ */
+export interface ViewportOffset {
+  x: number                            /* Horizontal offset */
+  y: number                            /* Vertical offset */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve viewport offset
+ *
+ * On iOS Safari, viewport offset can be negative due to overflow scrolling.
+ * As this may induce strange behaviors downstream, we'll just limit it to 0.
+ *
+ * @return Viewport offset
+ */
+export function getViewportOffset(): ViewportOffset {
+  return {
+    x: Math.max(0, pageXOffset),
+    y: Math.max(0, pageYOffset)
+  }
+}
+
+/**
+ * Set viewport offset
+ *
+ * @param offset - Viewport offset
+ */
+export function setViewportOffset(
+  { x, y }: Partial<ViewportOffset>
+): void {
+  window.scrollTo(x || 0, y || 0)
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch viewport offset
+ *
+ * @return Viewport offset observable
+ */
+export function watchViewportOffset(): Observable<ViewportOffset> {
+  return merge(
+    fromEvent<UIEvent>(window, "scroll"),
+    fromEvent<UIEvent>(window, "resize")
+  )
+    .pipe(
+      map(getViewportOffset),
+      startWith(getViewportOffset())
+    )
+}

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

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2016-2020 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 } from "rxjs"
+import { map, startWith } from "rxjs/operators"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Viewport size
+ */
+export interface ViewportSize {
+  width: number                        /* Viewport width */
+  height: number                       /* Viewport height */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Retrieve viewport size
+ *
+ * @return Viewport size
+ */
+export function getViewportSize(): ViewportSize {
+  return {
+    width:  innerWidth,
+    height: innerHeight
+  }
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Watch viewport size
+ *
+ * @return Viewport size observable
+ */
+export function watchViewportSize(): Observable<ViewportSize> {
+  return fromEvent<UIEvent>(window, "resize")
+    .pipe(
+      map(getViewportSize),
+      startWith(getViewportSize())
+    )
+}

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

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2016-2020 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, Subject, fromEventPattern } from "rxjs"
+import {
+  pluck,
+  share,
+  switchMapTo,
+  tap,
+  throttle
+} from "rxjs/operators"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Worker message
+ */
+export interface WorkerMessage {
+  type: unknown                        /* Message type */
+  data: unknown                        /* Message data */
+}
+
+/**
+ * Worker handler
+ *
+ * @template T - Message type
+ */
+export interface WorkerHandler<
+  T extends WorkerMessage
+> {
+  tx$: Subject<T>                      /* Message transmission subject */
+  rx$: Observable<T>                   /* Message receive observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Helper types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch options
+ *
+ * @template T - Worker message type
+ */
+interface WatchOptions<T extends WorkerMessage> {
+  tx$: Observable<T>                   /* Message transmission observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch a web worker
+ *
+ * This function returns an observable that will send all values emitted by the
+ * message observable to the web worker. Web worker communication is expected
+ * to be bidirectional (request-response) and synchronous. Messages that are
+ * emitted during a pending request are throttled, the last one is emitted.
+ *
+ * @param worker - Web worker
+ * @param options - Options
+ *
+ * @return Worker message observable
+ */
+export function watchWorker<T extends WorkerMessage>(
+  worker: Worker, { tx$ }: WatchOptions<T>
+): Observable<T> {
+
+  /* Intercept messages from worker-like objects */
+  const rx$ = fromEventPattern<Event>(next =>
+    worker.addEventListener("message", next)
+  )
+    .pipe(
+      pluck<Event, T>("data")
+    )
+
+  /* Send and receive messages, return hot observable */
+  return tx$
+    .pipe(
+      throttle(() => rx$, { leading: true, trailing: true }),
+      tap(message => worker.postMessage(message)),
+      switchMapTo(rx$),
+      share()
+    )
+}