[ZSH Documentation Enhancer] Make ZSH Documentation more readable #UserScript

ZSHDocumentationEnhancer.user.js

// ==UserScript==
// @name                            ZSH Documentation Enhancer
// @version                         0.3
// @description                     Make ZSH Documentation more readable
// @require                         http://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/highlight.min.js
// @resource theme                  http://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/tomorrow-night.min.css
// @resource bootstrap              https://bootswatch.com/4/darkly/bootstrap.min.css
// @author                          rjf89
// @match                           http://zsh.sourceforge.net/Doc/*
// @run-at                          document-start
// @grant                           GM_addStyle
// @grant                           GM_getResourceText
// ==/UserScript==

const STYLE_TWEAKS = `dd { border-width: thin; border-style: groove; margin: 0em 1em 1em 1em; }
dt > tt { margin: 0em 1em 1em 1em; color: chartreuse; }
dt > var { color: khaki; }
dd > p { margin: 1em 1em 1em 1em; }
.hljs { font-size: 1.1em; }`;

let concat = (previous, current) => [...previous, ...current];
let flatMap = (xs, fn) => xs.map(fn).reduce(concat, []);
function hlCode(e) {
    if (!e.classList.contains('language-bash')) {
        e.classList.add('language-bash');
        window.hljs.highlightBlock(e);
    }
}

function process(e) {
    if (e.tagName == 'PRE') hlCode(e);
    else if (e.childElementCount > 0) [...e.getElementsByTagName('pre')].forEach(hlCode);
}

(function() {
    "use strict";
    GM_addStyle(GM_getResourceText('theme'));
    GM_addStyle(GM_getResourceText('bootstrap'));
    GM_addStyle(STYLE_TWEAKS);
    [...document.getElementsByTagName('pre')].forEach(hlCode);
    new MutationObserver(ms => { flatMap(ms, m => m.addedNodes).forEach(process) }).observe(document, {childList: true, subtree: true});
})();