Adds a Watch Later button to videos on the YouTube subscriptions feed
// ==UserScript==
// @name YouTube Subscriptions Watch Later Button
// @namespace https://github.com/CharlesMagnuson/YouTube-Subscriptions-Watch-Later-Button
// @version 1.0
// @description Adds a Watch Later button to videos on the YouTube subscriptions feed
// @author CharlesMagnuson
// @match https://www.youtube.com/*
// @grant none
// @run-at document-idle
// ==/UserScript==
/*
╔══════════════════════════════════════════════════════════════════════════════╗
║ YOUTUBE SUBSCRIPTIONS WATCH LATER ║
║ Version 1.0 ║
╠══════════════════════════════════════════════════════════════════════════════╣
║ PURPOSE: ║
║ Adds a "Watch Later" button overlay to video thumbnails on the YouTube ║
║ subscriptions feed (/feed/subscriptions). This replicates the functionality ║
║ that exists on channel pages but is mysteriously absent from the sub feed. ║
║ ║
║ HOW IT WORKS: ║
║ 1. Monitors for video elements appearing on the subscriptions feed ║
║ 2. Injects a Watch Later button on each thumbnail (top-left corner) ║
║ 3. Uses YouTube's internal API to add/remove videos from Watch Later ║
║ 4. Authenticates using your existing YouTube session (SAPISIDHASH) ║
║ ║
║ BUTTON STATES: ║
║ - Clock icon (hollow): Video is NOT in Watch Later ║
║ - Checkmark icon (green bg): Video IS in Watch Later ║
║ ║
║ SECURITY NOTES: ║
║ - Only runs on youtube.com (verified by @match directive) ║
║ - Uses your existing authenticated session - no credentials stored ║
║ - All API calls go to official YouTube endpoints ║
╚══════════════════════════════════════════════════════════════════════════════╝
*/
(function() {
'use strict';
// =========================================================================
// SECTION 1: CONFIGURATION
// =========================================================================
// SVG paths for button icons
const SVG_PATH_CLOCK = "M14.97,16.95L10,13.87V7h2v5.76l4.03,2.49L14.97,16.95z M12,3c-4.96,0-9,4.04-9,9s4.04,9,9,9s9-4.04,9-9S16.96,3,12,3 M12,2c5.52,0,10,4.48,10,10s-4.48,10-10,10S2,17.52,2,12S6.48,2,12,2L12,2z";
const SVG_PATH_CHECKMARK = "M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41L9 16.17z";
// =========================================================================
// SECTION 2: CSS STYLES
// =========================================================================
function injectStyles() {
const styleId = 'yt-wl-custom-styles';
if (document.getElementById(styleId)) return;
const css = `
.yt-wl-custom-button {
opacity: 0.75 !important;
transition: opacity 0.15s ease, background-color 0.15s ease !important;
}
.yt-wl-custom-button:hover {
opacity: 1 !important;
}
`;
const style = document.createElement('style');
style.id = styleId;
style.textContent = css;
document.head.appendChild(style);
}
// =========================================================================
// SECTION 3: AUTHENTICATION
// =========================================================================
/**
* Generates SAPISIDHASH for YouTube API authentication.
* This is the same authentication method YouTube uses internally.
*/
async function getSApiSidHash(sapisid, origin) {
async function sha1(str) {
const buffer = new TextEncoder().encode(str);
const hashBuffer = await window.crypto.subtle.digest('SHA-1', buffer);
const hashArray = Array.from(new Uint8Array(hashBuffer));
return hashArray.map(b => ('00' + b.toString(16)).slice(-2)).join('');
}
const timestamp = Date.now();
const digest = await sha1(`${timestamp} ${sapisid} ${origin}`);
return `${timestamp}_${digest}`;
}
function getSapisidCookie() {
const cookies = document.cookie.split('; ');
for (const cookie of cookies) {
if (cookie.startsWith('SAPISID=')) {
return cookie.substring(8);
}
}
return null;
}
// =========================================================================
// SECTION 4: YOUTUBE API
// =========================================================================
/**
* Checks if a video is currently in the Watch Later playlist.
*/
async function isVideoInWatchLater(videoId) {
const sapisid = getSapisidCookie();
if (!sapisid) return false;
try {
const sapisidhash = await getSApiSidHash(sapisid, window.origin);
const response = await fetch(
'https://www.youtube.com/youtubei/v1/playlist/get_add_to_playlist',
{
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Authorization': `SAPISIDHASH ${sapisidhash}`
},
body: JSON.stringify({
context: {
client: {
clientName: 'WEB',
clientVersion: window.ytcfg?.data_?.INNERTUBE_CLIENT_VERSION || '2.20231219.04.00'
}
},
excludeWatchLater: false,
videoIds: [videoId]
})
}
);
if (!response.ok) return false;
const json = await response.json();
const playlists = json?.contents?.[0]?.addToPlaylistRenderer?.playlists;
if (playlists) {
const watchLater = playlists.find(p => p.playlistAddToOptionRenderer?.playlistId === 'WL');
if (watchLater) {
return watchLater.playlistAddToOptionRenderer.containsSelectedVideos === 'ALL';
}
}
return false;
} catch {
return false;
}
}
/**
* Adds or removes a video from Watch Later.
*/
async function toggleWatchLater(videoId, isCurrentlyInWatchLater) {
const sapisid = getSapisidCookie();
if (!sapisid) return false;
try {
const sapisidhash = await getSApiSidHash(sapisid, window.origin);
const actionObj = isCurrentlyInWatchLater
? { removedVideoId: videoId, action: 'ACTION_REMOVE_VIDEO_BY_VIDEO_ID' }
: { addedVideoId: videoId, action: 'ACTION_ADD_VIDEO' };
const response = await fetch(
'https://www.youtube.com/youtubei/v1/browse/edit_playlist',
{
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Authorization': `SAPISIDHASH ${sapisidhash}`
},
body: JSON.stringify({
context: {
client: {
clientName: 'WEB',
clientVersion: window.ytcfg?.data_?.INNERTUBE_CLIENT_VERSION || '2.20231219.04.00'
}
},
actions: [actionObj],
playlistId: 'WL'
})
}
);
return response.ok;
} catch {
return false;
}
}
// =========================================================================
// SECTION 5: VIDEO ID EXTRACTION
// =========================================================================
function extractVideoId(videoElement) {
const videoLink = videoElement.querySelector('a[href*="/watch?v="]');
if (videoLink) {
const href = videoLink.getAttribute('href');
const match = href.match(/[?&]v=([a-zA-Z0-9_-]{11})/);
if (match) return match[1];
}
return null;
}
// =========================================================================
// SECTION 6: BUTTON CREATION
// =========================================================================
function createWatchLaterButton(videoId) {
const container = document.createElement('div');
container.className = 'yt-wl-custom-button';
container.setAttribute('data-video-id', videoId);
container.setAttribute('data-in-watch-later', 'unknown');
container.style.cssText = `
position: absolute;
top: 8px;
left: 8px;
width: 36px;
height: 36px;
background-color: rgba(0, 0, 0, 0.7);
border-radius: 4px;
cursor: pointer;
display: flex;
align-items: center;
justify-content: center;
z-index: 9999;
pointer-events: auto;
box-shadow: 0 1px 3px rgba(0,0,0,0.3);
`;
const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
svg.setAttribute('viewBox', '0 0 24 24');
svg.setAttribute('width', '22');
svg.setAttribute('height', '22');
svg.style.fill = 'white';
svg.style.pointerEvents = 'none';
const path = document.createElementNS('http://www.w3.org/2000/svg', 'path');
path.setAttribute('d', SVG_PATH_CLOCK);
svg.appendChild(path);
container.appendChild(svg);
container.title = 'Add to Watch Later';
// Prevent mousedown from triggering thumbnail highlight
container.addEventListener('mousedown', (e) => {
e.preventDefault();
e.stopPropagation();
e.stopImmediatePropagation();
}, true);
// Click handler with optimistic UI update
container.addEventListener('click', async (e) => {
// Stop ALL event propagation to prevent thumbnail highlight
e.preventDefault();
e.stopPropagation();
e.stopImmediatePropagation();
const wasInWL = container.getAttribute('data-in-watch-later') === 'true';
const newState = !wasInWL;
// OPTIMISTIC UPDATE: Change button immediately before API call
container.setAttribute('data-in-watch-later', newState.toString());
path.setAttribute('d', newState ? SVG_PATH_CHECKMARK : SVG_PATH_CLOCK);
container.title = newState ? 'In Watch Later (click to remove)' : 'Add to Watch Later';
container.style.backgroundColor = newState ? 'rgba(0, 100, 0, 0.8)' : 'rgba(0, 0, 0, 0.7)';
// Make API call in background
const success = await toggleWatchLater(videoId, wasInWL);
// Only revert if the API call failed
if (!success) {
container.setAttribute('data-in-watch-later', wasInWL.toString());
path.setAttribute('d', wasInWL ? SVG_PATH_CHECKMARK : SVG_PATH_CLOCK);
container.title = wasInWL ? 'In Watch Later (click to remove)' : 'Add to Watch Later';
container.style.backgroundColor = wasInWL ? 'rgba(0, 100, 0, 0.8)' : 'rgba(0, 0, 0, 0.7)';
// Flash red to indicate error
container.style.backgroundColor = 'rgba(180, 0, 0, 0.8)';
setTimeout(() => {
container.style.backgroundColor = wasInWL ? 'rgba(0, 100, 0, 0.8)' : 'rgba(0, 0, 0, 0.7)';
}, 1500);
}
}, true); // Use capture phase to intercept event early
// Check initial Watch Later status
setTimeout(async () => {
const isInWL = await isVideoInWatchLater(videoId);
container.setAttribute('data-in-watch-later', isInWL.toString());
path.setAttribute('d', isInWL ? SVG_PATH_CHECKMARK : SVG_PATH_CLOCK);
container.title = isInWL ? 'In Watch Later (click to remove)' : 'Add to Watch Later';
if (isInWL) {
container.style.backgroundColor = 'rgba(0, 100, 0, 0.8)';
}
}, 100);
return container;
}
// =========================================================================
// SECTION 7: VIDEO PROCESSING
// =========================================================================
const processedElements = new Set();
function processVideoElement(videoElement) {
if (videoElement.hasAttribute('data-yt-wl-processed')) return;
const videoId = extractVideoId(videoElement);
if (!videoId) return;
// Find thumbnail container
let container = videoElement.querySelector('.yt-lockup-view-model__content-image');
if (!container) container = videoElement.querySelector('#thumbnail');
if (!container) container = videoElement.querySelector('ytd-thumbnail');
if (!container) container = videoElement.querySelector('a[href*="/watch"]');
if (!container) return;
videoElement.setAttribute('data-yt-wl-processed', 'true');
processedElements.add(videoElement);
// Ensure container has relative positioning
const style = window.getComputedStyle(container);
if (style.position === 'static') {
container.style.position = 'relative';
}
container.appendChild(createWatchLaterButton(videoId));
}
function scanForVideos() {
if (window.location.pathname !== '/feed/subscriptions') return;
document.querySelectorAll('ytd-rich-item-renderer').forEach(element => {
processVideoElement(element);
});
}
// =========================================================================
// SECTION 8: PAGE OBSERVATION
// =========================================================================
function setupObserver() {
const observer = new MutationObserver((mutations) => {
if (window.location.pathname !== '/feed/subscriptions') return;
let shouldScan = false;
for (const mutation of mutations) {
for (const node of mutation.addedNodes) {
if (node.nodeType === Node.ELEMENT_NODE) {
if (node.tagName === 'YTD-RICH-ITEM-RENDERER' ||
node.querySelector?.('ytd-rich-item-renderer')) {
shouldScan = true;
break;
}
}
}
if (shouldScan) break;
}
if (shouldScan) {
clearTimeout(window._ytWLScanTimeout);
window._ytWLScanTimeout = setTimeout(scanForVideos, 200);
}
});
observer.observe(document.querySelector('ytd-app') || document.body, {
childList: true,
subtree: true
});
}
function setupNavigationListener() {
const originalPushState = history.pushState;
history.pushState = function(...args) {
originalPushState.apply(this, args);
handleNavigation();
};
const originalReplaceState = history.replaceState;
history.replaceState = function(...args) {
originalReplaceState.apply(this, args);
handleNavigation();
};
window.addEventListener('popstate', handleNavigation);
function handleNavigation() {
processedElements.clear();
setTimeout(scanForVideos, 500);
}
}
// =========================================================================
// SECTION 9: INITIALIZATION
// =========================================================================
function init() {
injectStyles();
setupObserver();
setupNavigationListener();
scanForVideos();
}
if (document.readyState === 'loading') {
document.addEventListener('DOMContentLoaded', init);
} else {
init();
}
})();