117 lines
3.3 KiB
JavaScript
117 lines
3.3 KiB
JavaScript
/* global document */
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/**
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* Link Favicon Module
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*
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* Displays favicons for external links using DuckDuckGo's favicon service.
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* Based on the linkfavicon plugin by Shao Yanmin.
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*
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* Note: DDG returns a grey placeholder icon for domains without favicons.
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* Detecting this placeholder client-side is not reliably possible due to
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* CORS restrictions preventing canvas pixel inspection.
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*/
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(function () {
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'use strict';
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var Luxtools = window.Luxtools || (window.Luxtools = {});
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// Cache states for favicon URLs
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var ICON_NOT_FOUND = -1;
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var ICON_LOADING = 0;
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var ICON_LOADED = 1;
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var faviconCache = {};
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/**
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* Preload an image to verify it loads.
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* @param {string} src - Image URL to load
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* @returns {Promise} Resolves on load, rejects on error
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*/
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function loadImage(src) {
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return new Promise(function (resolve, reject) {
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var image = new Image();
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image.addEventListener('load', resolve);
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image.addEventListener('error', reject);
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image.src = src;
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});
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}
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/**
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* Apply the favicon as background image to all matching links.
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* @param {string} faviconUrl - The favicon URL to apply
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*/
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function applyFavicon(faviconUrl) {
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if (faviconCache[faviconUrl] !== ICON_LOADED) return;
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var links = document.querySelectorAll('[data-linkfavicon="' + faviconUrl + '"]');
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for (var i = 0; i < links.length; i++) {
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links[i].classList.add('linkfavicon');
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links[i].style.backgroundImage = 'url(' + faviconUrl + ')';
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}
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}
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/**
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* Get domain from URL.
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* @param {string} url - Full URL
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* @returns {string|null} Domain or null if invalid
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*/
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function getDomain(url) {
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try {
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var parsed = new URL(url);
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return parsed.hostname;
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} catch (e) {
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return null;
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}
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}
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/**
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* Initialize favicons for all external links on the page.
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*/
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function init() {
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// Find all external links (DokuWiki marks them with class 'urlextern')
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var links = document.querySelectorAll('a.urlextern');
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for (var i = 0; i < links.length; i++) {
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var link = links[i];
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var href = link.getAttribute('href');
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if (!href) continue;
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var domain = getDomain(href);
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if (!domain) continue;
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// DuckDuckGo favicon service URL
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var faviconUrl = 'https://icons.duckduckgo.com/ip3/' + domain + '.ico';
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// Mark the link with the favicon URL for later reference
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link.setAttribute('data-linkfavicon', faviconUrl);
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// Load and cache the favicon if not already processed
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if (faviconCache[faviconUrl] === undefined) {
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faviconCache[faviconUrl] = ICON_LOADING;
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(function (url) {
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loadImage(url)
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.then(function () {
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faviconCache[url] = ICON_LOADED;
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applyFavicon(url);
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})
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.catch(function () {
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faviconCache[url] = ICON_NOT_FOUND;
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});
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})(faviconUrl);
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} else if (faviconCache[faviconUrl] === ICON_LOADED) {
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// Already loaded, apply immediately
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link.classList.add('linkfavicon');
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link.style.backgroundImage = 'url(' + faviconUrl + ')';
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}
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}
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}
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// Export for potential external use
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Luxtools.LinkFavicon = {
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init: init
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};
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// Initialize when DOM is ready
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document.addEventListener('DOMContentLoaded', init, false);
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})();
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