Demo: https://www.youtube.com/watch?v=07uYCbxDcqU

Cleanup Twitter

// ==UserScript==
// @name    Cleanup Twitter.
// @include https://twitter.com/*
// ==/UserScript==

// v12: Hover over username / avatar for 100% opacity.
// v13: Add link to demo. https://www.youtube.com/watch?v=07uYCbxDcqU
// v14: refactor rm() and addClass() functions. Remove Messages popup at lower-right. Opacity more subtle.

// Use with TamperMonkey: https://www.tampermonkey.net/

function rm(sel) { document.querySelectorAll(sel).forEach((e) => e.remove()); }
function addClass(sel,clz) { document.querySelectorAll(sel).forEach((e) => e.classList.add(clz)); }

function cleanup() {
    const start = performance.now();
    ["Twitter", "Verified account","Trending", "Twitter Blue", "Bookmarks", "Share Tweet"].forEach(function(str) {
        rm(`[aria-label="${str}"]`);
    });
    ["Home", "Search and explore", "Notifications", "Direct Messages", "Profile","Account menu"].forEach(function(str) {
        addClass(`[aria-label="${str}"]`,'uxButton');
    });
    rm(`[aria-label*="View Tweet analytics"]`);

    for (const span of document.querySelectorAll('span')) {
        if (span.textContent === 'Show this thread') {
            span.remove();
        }
    }
    addClass('[data-testid="User-Names"]', 'tweakedUsername');
    rm('[data-testid="DMDrawer"]');

    ["More", ". Reply", ". Retweet", ". Like"].forEach(function(str) {
        addClass(`[aria-label*="${str}"]`,'uxButton');
    });
    addClass('div[data-testid="Tweet-User-Avatar"]','tweakedAvatar');
    addClass('a[data-testid="SideNav_NewTweet_Button"]','tweakedTweet');

    const end = performance.now();
    //console.log(`Code took ${end - start} milliseconds to run.`);
}

var styleElement = document.createElement('style', {type: 'text/css'});
styleElement.innerHTML = ".tweakedUsername{opacity:0.1}.tweakedUsername:hover{opacity:1}"+
    ".tweakedTweet{opacity:0.4}.tweakedAvatar{opacity:0.65}.tweakedAvatar:hover{opacity:1}"+
    ".uxButton {opacity: 0.45;}.uxButton:hover {opacity: 1;}";
document.head.appendChild(styleElement);


function debounce(fn, delay) {
    let timer = null;
    return function() {
        clearTimeout(timer);
        timer = setTimeout(function() {
            fn.apply(this, arguments);
        }, delay);
    };
}
var debouncedCleanup = debounce(cleanup, 150);
cleanup();

var observer = new MutationObserver(function(mutations) {
    for (var mutation of mutations) {
        if (mutation.type === 'childList' && mutation.addedNodes.length > 0) {
            debouncedCleanup();
            return;
        }
    }
});

observer.observe(document.body, {
    childList: true, subtree: true
});