E621 Image Mirror Replacer

Replace static1.e621.net with static1.e926.net before the browser tries to load images/videos

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         E621 Image Mirror Replacer
// @namespace    http://tampermonkey.net/
// @version      1.4
// @description  Replace static1.e621.net with static1.e926.net before the browser tries to load images/videos
// @author       You
// @match        *://e621.net/*
// @grant        none
// @run-at       document-start
// ==/UserScript==

(function () {
    'use strict';

    const OLD_HOST = 'static1.e621.net';
    const NEW_HOST = 'static1.e926.net';

    // Replace old host in a string
    function replaceHost(str) {
        return str.includes(OLD_HOST) ? str.replaceAll(OLD_HOST, NEW_HOST) : str;
    }

    // Intercept element.setAttribute
    const originalSetAttribute = Element.prototype.setAttribute;
    Element.prototype.setAttribute = function (name, value) {
        if (typeof value === 'string' && ['src', 'href', 'poster', 'data-src'].includes(name)) {
            value = replaceHost(value);
        }
        return originalSetAttribute.call(this, name, value);
    };

    // Intercept property assignments like el.src = ...
    const overrideProperty = (proto, prop) => {
        const descriptor = Object.getOwnPropertyDescriptor(proto, prop);
        if (!descriptor || !descriptor.set || !descriptor.get) return;

        Object.defineProperty(proto, prop, {
            get: descriptor.get,
            set: function (val) {
                if (typeof val === 'string') val = replaceHost(val);
                return descriptor.set.call(this, val);
            },
            configurable: true,
            enumerable: true,
        });
    };

    // Intercept image/video/link loads
    overrideProperty(HTMLImageElement.prototype, 'src');
    overrideProperty(HTMLSourceElement.prototype, 'src');
    overrideProperty(HTMLVideoElement.prototype, 'src');
    overrideProperty(HTMLLinkElement.prototype, 'href');
    overrideProperty(HTMLAnchorElement.prototype, 'href');

    // Handle early DOM already present (just in case)
    const ATTRIBUTES = ['src', 'href', 'poster', 'data-src'];
    const selector = ATTRIBUTES.map(attr => `[${attr}*="${OLD_HOST}"]`).join(',');
    const fixExisting = () => {
        document.querySelectorAll(selector).forEach(el => {
            ATTRIBUTES.forEach(attr => {
                if (el.hasAttribute(attr)) {
                    const val = el.getAttribute(attr);
                    if (val.includes(OLD_HOST)) {
                        el.setAttribute(attr, replaceHost(val));
                    }
                }
            });
        });
    };

    // MutationObserver as fallback for dynamically added elements
    const observer = new MutationObserver(mutations => {
        mutations.forEach(mutation => {
            mutation.addedNodes.forEach(node => {
                if (node.nodeType === Node.ELEMENT_NODE) {
                    fixExisting();
                }
            });
        });
    });

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

    // Just in case anything's already there
    fixExisting();
})();