Slack Web Workspace Sidebar

slack-web-workspace-sidebar.user.js

// ==UserScript==
// @name         Slack Web Workspace Sidebar
// @description  Enable the workspace sidebar on the web version of Slack.
// @namespace    https://github.com/PiDelport/
// @author       Pi Delport <pjdelport@gmail.com>
// @version      1.0
// @license      MIT
// @homepageURL  https://gist.github.com/PiDelport/513676916e8fc186a09edfc8965a410b
// @match        https://app.slack.com/*
// ==/UserScript==

(function() {
    'use strict';

    // See:
    // https://webapps.stackexchange.com/questions/144258/slacks-web-version-shows-workspace-switching-sidebar-but-only-on-chromebooks
    //
    // This seems to be the minimal change to make Slack detect Chrome OS, as of 2020-09-25:
    Object.defineProperty(navigator, 'userAgent', {
        value: navigator.userAgent + ' CrOS'
    });

})();

Also hosted at:

• https://greasyfork.org/en/scripts/411959-slack-web-workspace-sidebar
• https://openuserjs.org/scripts/PiDelport/Slack_Web_Workspace_Sidebar

This doesn't work in Firefox, as Firefox doesn't allow executing Javascript on pages with proper Content Security Policies, like Slack has. Unless one wants to set security.csp.enable = false, which is obviously bad for security, there doesn't seem to be a working workaround.

Tampermonkey claims to have one (Tampermonkey/tampermonkey#952 (comment)), however I could get that to work (not even with disabled service workers and caching).

Violentmonkey has another workaround (https://violentmonkey.github.io/posts/inject-into-context/), however they explicitly state that this then results in the userscripts to run in another context than the Javascript on the page. I also tried that and can confirm that while the script gets executed, the changed user agent isn't visible to the page.