wowhead-dressing-room-background-replacer.js

// ==UserScript==
// @name         Wowhead Dressing Room Background Replacer
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Replaces the model viewer background with a 1x1 green pixel
// @author       You
// @match        https://www.wowhead.com/classic/dressing-room*
// @run-at       document-start
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const TARGET_URL = 'https://wow.zamimg.com/modelviewer/classic/background-181818.png';
    // 1x1 green pixel as a data URI
    const GREEN_PIXEL = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M/wHwAEBgIApD5fRAAAAABJRU5ErkJggg==';

    // Override fetch
    const originalFetch = window.fetch;
    window.fetch = function(url, options) {
        if (url && url.toString().includes('background-181818.png')) {
            return originalFetch(GREEN_PIXEL, options);
        }
        return originalFetch.apply(this, arguments);
    };

    // Override XMLHttpRequest
    const originalOpen = XMLHttpRequest.prototype.open;
    XMLHttpRequest.prototype.open = function(method, url, ...rest) {
        if (url && url.toString().includes('background-181818.png')) {
            return originalOpen.call(this, method, GREEN_PIXEL, ...rest);
        }
        return originalOpen.apply(this, arguments);
    };

    // Override Image src setter for dynamically created images
    const originalImageDescriptor = Object.getOwnPropertyDescriptor(HTMLImageElement.prototype, 'src');
    Object.defineProperty(HTMLImageElement.prototype, 'src', {
        get: function() {
            return originalImageDescriptor.get.call(this);
        },
        set: function(value) {
            if (value && value.toString().includes('background-181818.png')) {
                return originalImageDescriptor.set.call(this, GREEN_PIXEL);
            }
            return originalImageDescriptor.set.call(this, value);
        }
    });

    console.log('[BG Replacer] Script loaded - background image will be replaced with green pixel');
})();