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