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Jsdelivr Auto Fallback

修复 cdn.jsdelivr.net 无法访问的问题

  1. // ==UserScript==
  2. // @name Jsdelivr Auto Fallback
  3. // @namespace https://github.com/PipecraftNet/jsdelivr-auto-fallback
  4. // @version 0.3.3
  5. // @author PipecraftNet&DreamOfIce
  6. // @description 修复 cdn.jsdelivr.net 无法访问的问题
  7. // @homepage https://github.com/PipecraftNet/jsdelivr-auto-fallback
  8. // @supportURL https://github.com/PipecraftNet/jsdelivr-auto-fallback/issues
  9. // @license MIT
  10. // @match *://*/*
  11. // @run-at document-start
  12. // @grant GM_setValue
  13. // @grant GM_getValue
  14. // ==/UserScript==
  15.  
  16. ((document) => {
  17.   'use strict';
  18.   let fastNode;
  19.   let failed;
  20.   let isRunning;
  21.   const DEST_LIST = [
  22.     'cdn.jsdelivr.net',
  23.     'fastly.jsdelivr.net',
  24.  
  25.     'testingcf.jsdelivr.net',
  26.     'test1.jsdelivr.net',
  27.     'gcore.jsdelivr.net'
  28.   ];
  29.   const PREFIX = '//';
  30.   const SOURCE = DEST_LIST[0];
  31.   const starTime = Date.now();
  32.   const TIMEOUT = 2000;
  33.   const STORE_KEY = 'jsdelivr-auto-fallback';
  34.   const TEST_PATH = '/gh/PipecraftNet/jsdelivr-auto-fallback@main/empty.css?';
  35.   const shouldReplace = (text) => text && text.includes(PREFIX + SOURCE);
  36.   const replace = (text) => text.replace(PREFIX + SOURCE, PREFIX + fastNode);
  37.   const setTimeout = window.setTimeout;
  38.   const $ = document.querySelectorAll.bind(document);
  39.  
  40.   const replaceElementSrc = () => {
  41.     let element;
  42.     let value;
  43.     for (element of $('link[rel="stylesheet"]')) {
  44.       value = element.href;
  45.       if (shouldReplace(value) && !value.includes(TEST_PATH)) {
  46.         element.href = replace(value);
  47.       }
  48.     }
  49.  
  50.     for (element of $('script')) {
  51.       value = element.src;
  52.       if (shouldReplace(value)) {
  53.         const newNode = document.createElement('script');
  54.         newNode.src = replace(value);
  55.         element.defer = true;
  56.         element.src = '';
  57.         element.before(newNode);
  58.         element.remove();
  59.       }
  60.     }
  61.  
  62.     for (element of $('img')) {
  63.       value = element.src;
  64.       if (shouldReplace(value)) {
  65.         // Used to cancel loading. Without this line it will remain pending status.
  66.         element.src = '';
  67.         element.src = replace(value);
  68.       }
  69.     }
  70.  
  71.     // All elements that have a style attribute
  72.     for (element of $('*[style]')) {
  73.       value = element.getAttribute('style');
  74.       if (shouldReplace(value)) {
  75.         element.setAttribute('style', replace(value));
  76.       }
  77.     }
  78.  
  79.     for (element of $('style')) {
  80.       value = element.innerHTML;
  81.       if (shouldReplace(value)) {
  82.         element.innerHTML = replace(value);
  83.       }
  84.     }
  85.   };
  86.  
  87.   const tryReplace = () => {
  88.     if (!isRunning && failed && fastNode) {
  89.       console.warn(SOURCE + ' is not available. Use ' + fastNode);
  90.       isRunning = true;
  91.       setTimeout(replaceElementSrc, 0);
  92.       // Some need to wait for a while
  93.       setTimeout(replaceElementSrc, 20);
  94.       // Replace dynamically added elements
  95.       setInterval(replaceElementSrc, 500);
  96.     }
  97.   };
  98.  
  99.   const checkAvailable = (url, callback) => {
  100.     let timeoutId;
  101.     const newNode = document.createElement('link');
  102.     const handleResult = (isSuccess) => {
  103.       if (!timeoutId) {
  104.         return;
  105.       }
  106.  
  107.       clearTimeout(timeoutId);
  108.       timeoutId = 0;
  109.       // Used to cancel loading. Without this line it will remain pending status.
  110.       if (!isSuccess) newNode.href = 'data:text/plain;base64,';
  111.       newNode.remove();
  112.       callback(isSuccess);
  113.     };
  114.  
  115.     timeoutId = setTimeout(handleResult, TIMEOUT);
  116.  
  117.     newNode.addEventListener('error', () => handleResult(false));
  118.     newNode.addEventListener('load', () => handleResult(true));
  119.     newNode.rel = 'stylesheet';
  120.     newNode.text = 'text/css';
  121.     newNode.href = url + TEST_PATH + starTime;
  122.     document.head.insertAdjacentElement('afterbegin', newNode);
  123.   };
  124.  
  125.   const cached = (() => {
  126.     try {
  127.       // eslint-disable-next-line new-cap
  128.       return Object.assign({}, GM_getValue(STORE_KEY));
  129.     } catch {
  130.       return {};
  131.     }
  132.   })();
  133.  
  134.   const main = () => {
  135.     cached.time = starTime;
  136.     cached.failed = false;
  137.     cached.fastNode = null;
  138.  
  139.     for (const url of DEST_LIST) {
  140.       checkAvailable('https://' + url, (isAvailable) => {
  141.         // console.log(url, Date.now() - starTime, Boolean(isAvailable));
  142.         if (!isAvailable && url === SOURCE) {
  143.           failed = true;
  144.           cached.failed = true;
  145.         }
  146.  
  147.         if (isAvailable && !fastNode) {
  148.           fastNode = url;
  149.         }
  150.  
  151.         if (isAvailable && !cached.fastNode) {
  152.           cached.fastNode = url;
  153.         }
  154.  
  155.         tryReplace();
  156.       });
  157.     }
  158.  
  159.     setTimeout(() => {
  160.       // If all domains are timeout
  161.       if (failed && !fastNode) {
  162.         fastNode = DEST_LIST[1];
  163.         tryReplace();
  164.       }
  165.  
  166.       // eslint-disable-next-line new-cap
  167.       GM_setValue(STORE_KEY, cached);
  168.     }, TIMEOUT + 100);
  169.   };
  170.  
  171.   if (
  172.     cached.time &&
  173.     starTime - cached.time < 60 * 60 * 1000 &&
  174.     cached.failed &&
  175.     cached.fastNode
  176.   ) {
  177.     failed = true;
  178.     fastNode = cached.fastNode;
  179.     tryReplace();
  180.     setTimeout(main, 1000);
  181.   } else {
  182.     main();
  183.   }
  184. })(document);