Extra GitHub syntax highlighting

extra-github-highlighting.tampermonkey.js

// ==UserScript==
// @name         Extra GitHub syntax highlighting
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Add extra classes to TypeScript/JavaScript tokens for more granular syntax highlighting. Combine with something like StyleBot for fun and profit.
// @author       https://github.com/dannymcgee
// @include      /^https?:\/\/(.*)?\.github\.com\/?.*$/
// @require      https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js)
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const { flow, partition } = _;

    // Closures
    const test = (regexp) => ((elem) => regexp.test(elem.textContent.trim()));
    const addClass = (className) => (([matchingElements, remaining]) => {
        matchingElements.forEach((elem) => elem.classList.add(className));

        return remaining;
    });

    // Predicates
    const isOperator = test(/^[-+*/=.,;<>]|(>=|<=|=>|==|===|&&|\|\|)$/);
    const isNum =      test(/^\d+$/);
    const isConst =    test(/^(true|false|null|undefined)$/);
    const isThis =     test(/^this$/);
    const isPrim =     test(/^(string|number)$/);

    // Wait for DOMContentReady
    if (document.readyState != 'loading') {
        highlight();
    } else {
        document.addEventListener('DOMContentLoaded', highlight);
    }

    // Do the thing!
    function highlight() {
        flow(
            partition(isOperator), addClass('pl-operator'),
            partition(isNum),      addClass('pl-number'),
            partition(isConst),    addClass('pl-const'),
        )(
            document.querySelectorAll('.pl-c1')
        );

        flow(
            partition(isThis), addClass('pl-this'),
            partition(isPrim), addClass('pl-prim'),
        )(
            document.querySelectorAll('.pl-smi')
        );
    }
})();