rakunator

// ==UserScript==
// @name           Rakunator
// @namespace      http://huh
// @description    left/right arrow page nav
// @include        https://course.raku.org/*
// ==/UserScript==

let pages = [
"/essentials/what-is-raku/",
"/essentials/raku-vs-rakudo/",
"/essentials/how-to-install-rakudo/",
"/essentials/editors-and-ides/",
"/essentials/conventional-file-extensions/",
"/essentials/hello-world/",
"/essentials/on-unicode/",
"/essentials/running-programs/",
"/essentials/running-programs/from-command-line/",
"/essentials/running-programs/from-repl/",
"/essentials/running-programs/from-ide/",
"/essentials/running-programs/using-docker/",
"/essentials/running-programs/using-online-services/",
"/essentials/simple-input-output/",
"/essentials/simple-input-output/say/",
"/essentials/simple-input-output/prompt/",
"/essentials/comments/",
"/essentials/comments/single-line/",
"/essentials/comments/multi-line/",
"/essentials/comments/embedded/",
"/essentials/scalar-variables/",
"/essentials/scalar-variables/declaring-a-variable/",
"/essentials/scalar-variables/assigning-a-value/",
"/essentials/scalar-variables/declaration-with-initialization/",
"/essentials/scalar-variables/defined-or-operator/",
"/essentials/scalar-variables/identifiers/",
"/essentials/strings/",
"/essentials/strings/string-concatenation/",
"/essentials/strings/variable-interpolation/",
"/essentials/strings/code-interpolation/",
"/essentials/strings/escaping-special-characters/",
"/essentials/strings/string-length/",
"/essentials/numbers/",
"/essentials/numbers/integers/",
"/essentials/numbers/rats/",
"/essentials/numbers/numeric/",
"/essentials/numbers/operations/",
"/essentials/booleans/",
"/essentials/booleans/operations/",
"/essentials/booleans/boolean-operations-other-types/",
"/essentials/ranges/",
"/essentials/ranges/excluding-endpoints/",
"/essentials/ranges/matching-against-a-range/",
"/essentials/code-blocks/",
"/essentials/code-blocks/lexical-scope/",
"/essentials/code-blocks/global-variables/",
"/essentials/code-blocks/local-variables/",
"/essentials/conditional-checks/",
"/essentials/conditional-checks/if/",
"/essentials/conditional-checks/else/",
"/essentials/conditional-checks/elsif/",
"/essentials/conditional-checks/unless/",
"/essentials/conditional-checks/modifiers/",
"/essentials/conditional-checks/comparing-numbers/",
"/essentials/conditional-checks/comparing-strings/",
"/essentials/conditional-checks/ternary-operator/",
"/essentials/loops/",
"/essentials/loops/while/",
"/essentials/loops/until/",
"/essentials/loops/repeat/",
"/essentials/loops/modifiers/",
"/essentials/loops/loop/",
"/essentials/loops/infinite-loops/",
"/essentials/loops/for/",
"/essentials/loops/topic/",
"/essentials/loops/postfix-for/",
"/essentials/coercion/",
"/essentials/coercion/what/",
"/essentials/coercion/methods/",
"/essentials/coercion/new/",
"/essentials/coercion/prefixes/",
"/essentials/typed-variables/",
"/essentials/typed-variables/type-constraints/",
"/essentials/typed-variables/using-of/",
"/essentials/typed-variables/coercion/",
"/essentials/typed-variables/allomorphs/",
"/essentials/positionals/",
"/essentials/positionals/arrays/",
"/essentials/positionals/nested-arrays/",
"/essentials/positionals/args-array/",
"/essentials/positionals/interpolating-arrays/",
"/essentials/positionals/quoting-string-arrays/",
"/essentials/positionals/lists/",
"/essentials/positionals/subscripting-ranges/",
"/essentials/associatives/",
"/essentials/associatives/pairs/",
"/essentials/associatives/hashes/",
"/essentials/associatives/nested-hashes/",
"/essentials/associatives/interpolating-hashes/",
"/essentials/functions/",
"/essentials/functions/identifiers/",
"/essentials/functions/function-parameters/",
"/essentials/functions/return-result/",
"/essentials/functions/positional-parameters/",
"/essentials/functions/named-parameters/",
"/essentials/functions/default-values/",
"/essentials/more-on-functions/",
"/essentials/more-on-functions/mind-the-space/",
"/essentials/more-on-functions/typed-parameters/",
"/essentials/more-on-functions/return-type/",
"/essentials/more-on-functions/multi-functions/",
"/essentials/built-in-functions-for-printing/",
"/essentials/built-in-functions-for-printing/say/",
"/essentials/built-in-functions-for-printing/print/",
"/essentials/built-in-functions-for-printing/put/",
"/essentials/built-in-functions-for-printing/note/",
"/essentials/the-main-function/",
"/essentials/the-main-function/reading-command-line-arguments/",
"/essentials/the-main-function/multi-main-functions/",
"/essentials/the-main-function/using-unit-sub/"
];

var now = location.pathname;
var pos = pages.findIndex( el => (el == now) );

if (pos < 0)
  exit;

document.onkeydown = function(ev)
{
  if (ev.key == 'ArrowLeft' && pos > 0)
    pos--;
  else
  if (ev.key == 'ArrowRight' && pos < pages.length-1)
    pos++;
  else
    return;

  location.pathname = pages[pos];
}