Reddit Login Autofill helper

Show proxy form only when Reddit's login dialog is visible

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         Reddit Login Autofill helper
// @namespace    http://tampermonkey.net/
// @version      2.4
// @description  Show proxy form only when Reddit's login dialog is visible
// @author       bedweb
// @match        https://www.reddit.com/*
// @match        https://old.reddit.com/*
// @match        https://m.reddit.com/*
// @grant        none
// @run-at       document-idle
// @license      GNU GPLv3
// ==/UserScript==

(function () {
    'use strict';

    function log(...args) {
        console.log('[Reddit-Proxy-Autofill]', ...args);
    }

    let proxyForm;

    function createProxyForm() {
        if (proxyForm) return proxyForm;

        proxyForm = document.createElement('form');
        proxyForm.id = 'raf-proxy-form';
        proxyForm.style.position = 'fixed';
        proxyForm.style.top = '1rem';
        proxyForm.style.left = '1rem';
        proxyForm.style.zIndex = '99999';
        proxyForm.style.background = 'rgba(255,255,255,0.95)';
        proxyForm.style.padding = '0.5rem';
        proxyForm.style.borderRadius = '0.5rem';
        proxyForm.style.boxShadow = '0 2px 8px rgba(0,0,0,0.2)';
        proxyForm.innerHTML = `
      <input type="text" name="username" autocomplete="username"><br>
      <input type="password" name="password" autocomplete="current-password"><br>
      <div style="display:flex;justify-content:space-between;align-items:center;margin-bottom:0.25rem;">
        <button type="button" id="raf-close-btn" style="font-size:0.8rem;">close</button>
        <button type="button" id="raf-allowfocus-btn" style="font-size:0.8rem;">allowfocus</button>
        <button type="submit">inject to form</button>
      </div>

    `;
        proxyForm.addEventListener('submit', e => {
            e.preventDefault();
            transferCredentials(proxyForm.username.value, proxyForm.password.value);
        });
        proxyForm.querySelector('#raf-close-btn').addEventListener('click', () => {
            hideProxyForm();
        });
        proxyForm.querySelector('#raf-allowfocus-btn').addEventListener('click', () => {
            allowfocus();
        });

        return proxyForm;
    }

    function showProxyForm() {
        if (!document.body.contains(proxyForm)) {
            document.body.appendChild(proxyForm);
            log('Proxy form shown.');
        }
    }

    function hideProxyForm() {
        if (proxyForm && document.body.contains(proxyForm)) {
            proxyForm.remove();
            log('Proxy form hidden.');
        }
    }
    function allowfocus() {
        const tohide = DomUtils.traverseShadow(document, `div.justify-between.items-end`);
        tohide.style.display = "none";
    }

    function transferCredentials(username, password) {
        if (!username || !password) {
            alert('Please fill in both username and password.');
            return;
        }

        let injected = false;

        const transferField = (dummy, name) => {
            const real = DomUtils.traverseShadow(document, `input[name="${name}"]`);
            if (real && dummy) {
                real.value = dummy;
                real.dispatchEvent(new Event('input', { bubbles: true }));
                real.dispatchEvent(new Event('change', { bubbles: true }));
                return true;
            }
        };

        injected = transferField(username, 'username') && transferField(password, 'password');

        if (!injected) {
            alert('Could not inject credentials automatically. Please paste them manually.');
        }
    }

    function observeLoginModal() {
        const observer = new MutationObserver(() => {
            const modal = document.querySelector('auth-flow-modal');
            if (modal && modal.offsetParent !== null) {
                showProxyForm();
            } else {
                hideProxyForm();
            }
        });

        observer.observe(document.body, { childList: true, subtree: true });
    }
    /* Shared Utilities */
    const DomUtils = {
        waitForElement: (selector) => new Promise(resolve => {
            if (document.querySelector(selector)) return resolve();
            const observer = new MutationObserver(() => {
                if (document.querySelector(selector)) {
                    observer.disconnect();
                    resolve();
                }
            });
            observer.observe(document.body, { childList: true, subtree: true });
        }),

        traverseShadow: (root = document, selector) => {
            const walker = document.createTreeWalker(
                root,
                NodeFilter.SHOW_ELEMENT,
                {
                    acceptNode: node => node.shadowRoot ?
                        NodeFilter.FILTER_ACCEPT : NodeFilter.FILTER_SKIP
                }
            );

            while (walker.nextNode()) {
                const shadowRoot = walker.currentNode.shadowRoot;
                const element = shadowRoot.querySelector(selector);
                if (element) return element;
                const nested = DomUtils.traverseShadow(shadowRoot, selector);
                if (nested) return nested;
            }
            return null;
        }
    };

    proxyForm = createProxyForm();
    observeLoginModal();
})();