WhatsApp Colour Scheme Switcher

main.js

// ==UserScript==
// @name         WhatsApp Color Scheme Switcher
// @namespace    https://kaveenrodrigo.com/
// @version      0.1
// @description  WhatsApp Color Sceheme Switcher.
// @author       Kaveen Rodrigo
// @match        https://web.whatsapp.com/
// @grant        none
// ==/UserScript==

function setTheme(color) {
    document.body.className = color == "dark" ? "web dark" : "web";
}

(function() {
    'use strict';
    if (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) {
        setTheme("dark");
    }
    window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', e => {
        const newColorScheme = e.matches ? "dark" : "light";
        setTheme(newColorScheme);
    });
})();