前言
cdn.jsdelivr.net 国内无法访问时候,造成网站 js, css, image文件无法正常显示。
自动检查 cdn.jsdelivr.net 是否可用, 如果不可用时,会自动把所有 js, css, image 的地址切换到其他可用的域名。比如:gcore.jsdelivr.net
项目地址
本项目属于BestTools大佬的我只是转载。
使用方法
直接复制 index.js 或 index.min.js 里的内容,加到网站里。强烈建议添加到 head 标签最上面。
所有 script 标签加上 defer 属性。如果原来有 async 属性,可以跳过。这个可以避免 pending 状态带来的等待时间,大大提升性能。
示例:
<script defer src="index.js"></script>
<script defer src="index.min.js"></script>
index.js
((document) => {
'use strict';
let fastNode;
let failed;
let isRunning;
const DEST_LIST = [
'cdn.jsdelivr.net',
'fastly.jsdelivr.net',
'gcore.jsdelivr.net',
'cdn.zenless.top',
'testingcf.jsdelivr.net',
'test1.jsdelivr.net'
];
const PREFIX = '//';
const SOURCE = DEST_LIST[0];
const starTime = Date.now();
const TIMEOUT = 2000;
const STORE_KEY = 'jsdelivr-auto-fallback';
const TEST_PATH = '/gh/PipecraftNet/jsdelivr-auto-fallback@main/empty.css?';
const shouldReplace = (text) => text && text.includes(PREFIX + SOURCE);
const replace = (text) => text.replace(PREFIX + SOURCE, PREFIX + fastNode);
const setTimeout = window.setTimeout;
const $ = document.querySelectorAll.bind(document);
const replaceElementSrc = () => {
let element;
let value;
for (element of $('link[rel="stylesheet"]')) {
value = element.href;
if (shouldReplace(value) && !value.includes(TEST_PATH)) {
element.href = replace(value);
}
}
for (element of $('script')) {
value = element.src;
if (shouldReplace(value)) {
const newNode = document.createElement('script');
newNode.src = replace(value);
element.defer = true;
element.src = '';
element.before(newNode);
element.remove();
}
}
for (element of $('img')) {
value = element.src;
if (shouldReplace(value)) {
// Used to cancel loading. Without this line it will remain pending status.
element.src = '';
element.src = replace(value);
}
}
// All elements that have a style attribute
for (element of $('*[style]')) {
value = element.getAttribute('style');
if (shouldReplace(value)) {
element.setAttribute('style', replace(value));
}
}
for (element of $('style')) {
value = element.innerHTML;
if (shouldReplace(value)) {
element.innerHTML = replace(value);
}
}
};
const tryReplace = () => {
if (!isRunning && failed && fastNode) {
console.warn(SOURCE + ' is not available. Use ' + fastNode);
isRunning = true;
setTimeout(replaceElementSrc, 0);
// Some need to wait for a while
setTimeout(replaceElementSrc, 20);
// Replace dynamically added elements
setInterval(replaceElementSrc, 500);
}
};
const checkAvailable = (url, callback) => {
let timeoutId;
const newNode = document.createElement('link');
const handleResult = (isSuccess) => {
if (!timeoutId) {
return;
}
clearTimeout(timeoutId);
timeoutId = 0;
// Used to cancel loading. Without this line it will remain pending status.
if (!isSuccess) newNode.href = 'data:text/plain;base64,';
newNode.remove();
callback(isSuccess);
};
timeoutId = setTimeout(handleResult, TIMEOUT);
newNode.addEventListener('error', () => handleResult(false));
newNode.addEventListener('load', () => handleResult(true));
newNode.rel = 'stylesheet';
newNode.text = 'text/css';
newNode.href = url + TEST_PATH + starTime;
document.head.insertAdjacentElement('afterbegin', newNode);
};
const cached = (() => {
try {
return Object.assign(
{},
JSON.parse(localStorage.getItem(STORE_KEY) || '{}')
);
} catch {
return {};
}
})();
const main = () => {
cached.time = starTime;
cached.failed = false;
cached.fastNode = null;
for (const url of DEST_LIST) {
checkAvailable('https://' + url, (isAvailable) => {
// console.log(url, Date.now() - starTime, Boolean(isAvailable));
if (!isAvailable && url === SOURCE) {
failed = true;
cached.failed = true;
}
if (isAvailable && !fastNode) {
fastNode = url;
}
if (isAvailable && !cached.fastNode) {
cached.fastNode = url;
}
tryReplace();
});
}
setTimeout(() => {
// If all domains are timeout
if (failed && !fastNode) {
fastNode = DEST_LIST[1];
tryReplace();
}
localStorage.setItem(STORE_KEY, JSON.stringify(cached));
}, TIMEOUT + 100);
};
if (
cached.time &&
starTime - cached.time < 60 * 60 * 1000 &&
cached.failed &&
cached.fastNode
) {
failed = true;
fastNode = cached.fastNode;
tryReplace();
setTimeout(main, 1000);
} else {
main();
}
})(document);
index.min.js
(n=>{"use strict";let r,s,e;const l=["cdn.jsdelivr.net","fastly.jsdelivr.net","gcore.jsdelivr.net","cdn.zenless.top","testingcf.jsdelivr.net","test1.jsdelivr.net"],t="//",a=l[0],i=Date.now(),o=2e3,c="jsdelivr-auto-fallback",f="/gh/PipecraftNet/jsdelivr-auto-fallback@main/empty.css?",d=e=>e&&e.includes(t+a),m=e=>e.replace(t+a,t+r),u=window.setTimeout,v=n.querySelectorAll.bind(n),g=()=>{let e,t;for(e of v('link[rel="stylesheet"]'))t=e.href,d(t)&&!t.includes(f)&&(e.href=m(t));for(e of v("script"))if(t=e.src,d(t)){const r=n.createElement("script");r.src=m(t),e.defer=!0,e.src="",e.before(r),e.remove()}for(e of v("img"))t=e.src,d(t)&&(e.src="",e.src=m(t));for(e of v("*[style]"))t=e.getAttribute("style"),d(t)&&e.setAttribute("style",m(t));for(e of v("style"))t=e.innerHTML,d(t)&&(e.innerHTML=m(t))},y=()=>{!e&&s&&r&&(console.warn(a+" is not available. Use "+r),e=!0,u(g,0),u(g,20),setInterval(g,500))},b=(()=>{try{return Object.assign({},JSON.parse(localStorage.getItem(c)||"{}"))}catch{return{}}})();var h=()=>{b.time=i,b.failed=!1,b.fastNode=null;for(const t of l)((e,t)=>{let r;const s=n.createElement("link"),l=e=>{r&&(clearTimeout(r),r=0,e||(s.href="data:text/plain;base64,"),s.remove(),t(e))};r=u(l,o),s.addEventListener("error",()=>l(!1)),s.addEventListener("load",()=>l(!0)),s.rel="stylesheet",s.text="text/css",s.href=e+f+i,n.head.insertAdjacentElement("afterbegin",s)})("https://"+t,e=>{e||t!==a||(s=!0,b.failed=!0),e&&!r&&(r=t),e&&!b.fastNode&&(b.fastNode=t),y()});u(()=>{s&&!r&&(r=l[1],y()),localStorage.setItem(c,JSON.stringify(b))},o+100)};b.time&&i-b.time<36e5&&b.failed&&b.fastNode?(s=!0,r=b.fastNode,y(),u(h,1e3)):h()})(document);
jsdelivr可用地址
- fastly.jsdelivr.net
- gcore.jsdelivr.net
- testingcf.jsdelivr.net
- test1.jsdelivr.net