/*************************************************************
*
* Copyright (c) 2019-2022 The MathJax Consortium
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* The data for a CDN
*/
type CdnData = {
api: string, // URL for JSON containing version number
key: string, // key for versionb string in JSON data
base?: string // base URL for MathJax on the CDN (version is appended to get actual URL)
};
/**
* A map of server names to CDN data
*/
type CdnList = Map<string, CdnData>;
/**
* The data from a script tag for latest.js
*/
type ScriptData = {
tag: HTMLScriptElement, // the script DOM element
src: string, // the script's (possibly modified) source attribute
id: string, // the script's (possibly empty) id string
version: string, // the MathJax version where latest.js was loaded
dir: string, // the subdirectory where latest.js was loaded from (e.g., /es5)
file: string, // the file to be loaded by latest.js
cdn: CdnData // the CDN where latest.js was loaded
} | null;
/**
* Add XMLHttpRequest and ActiveXObject (for IE)
*/
declare const window: {
XMLHttpRequest: XMLHttpRequest;
ActiveXObject: any;
};
/*=====================================================================*/
/**
* The various CDNs and their data for how to obtain versions
*/
const CDN: CdnList = new Map([
['cdnjs.cloudflare.com', {
api: 'https://api.cdnjs.com/libraries/mathjax?fields=version',
key: 'version',
base: 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/'
}],
['rawcdn.githack.com', {
api: 'https://api.github.com/repos/mathjax/mathjax/releases/latest',
key: 'tag_name',
base: 'https://rawcdn.githack.com/mathjax/MathJax/'
}],
['gitcdn.xyz', {
api: 'https://api.github.com/repos/mathjax/mathjax/releases/latest',
key: 'tag_name',
base: 'https://gitcdn.xyz/mathjax/MathJax/'
}],
['cdn.statically.io', {
api: 'https://api.github.com/repos/mathjax/mathjax/releases/latest',
key: 'tag_name',
base: 'https://cdn.statically.io/gh/mathjax/MathJax/'
}],
['unpkg.com', {
api: 'https://api.github.com/repos/mathjax/mathjax/releases/latest',
key: 'tag_name',
base: 'https://unpkg.com/mathjax@'
}],
['cdn.jsdelivr.net', {
api: 'https://api.github.com/repos/mathjax/mathjax/releases/latest',
key: 'tag_name',
base: 'https://cdn.jsdelivr.net/npm/mathjax@'
}]
]);
/**
* The data for getting release versions from GitHub
*/
const GITHUB: CdnData = {
api: 'https://api.github.com/repos/mathjax/mathjax/releases',
key: 'tag_name'
};
/**
* The major version number for MathJax (we will load the highest version with this initial number)
*/
const MJX_VERSION = 3;
/**
* The name to use for the version in localStorage
*/
const MJX_LATEST = 'mjx-latest-version';
/**
* The amount of time a cached version number is valid
*/
const SAVE_TIME = 1000 * 60 * 60 * 24 * 7; // one week
/**
* Data for the script that loaded latest.js
*/
let script: ScriptData = null;
/*=====================================================================*/
/**
* Produce an error message on the console
*
* @param {string} message The error message to display
*/
function Error(message: string) {
if (console && console.error) {
console.error('MathJax(latest.js): ' + message);
}
}
/**
* Create a ScriptData object from the given script tag and CDN
*
* @param {HTMLScriptElement} script The script tag whose data is desired
* @param {CdnData} cdn The CDN data already obtained for the script (or null)
* @return {ScriptData} The data for the given script
*/
function scriptData(script: HTMLScriptElement, cdn: CdnData = null): ScriptData {
script.parentNode.removeChild(script);
let src = script.src;
let file = src.replace(/.*?\/latest\.js(\?|$)/, '');
if (file === '') {
file = 'startup.js';
src = src.replace(/\?$/, '') + '?' + file;
}
const version = (src.match(/(\d+\.\d+\.\d+)(\/es\d+)?\/latest.js\?/) || ['', ''])[1];
const dir = (src.match(/(\/es\d+)\/latest.js\?/) || ['', ''])[1] || '';
return {
tag: script,
src: src,
id: script.id,
version: version,
dir: dir,
file: file,
cdn: cdn
};
}
/**
* Check if a script refers to MathJax on one of the CDNs
*
* @param {HTMLScriptElement} script The script tag to check
* @return {ScriptData | null} Non-null if the script is from a MathJax CDN
*/
function checkScript(script: HTMLScriptElement): ScriptData | null {
for (const server of CDN.keys()) {
const cdn = CDN.get(server);
const url = cdn.base;
const src = script.src;
if (src && src.substr(0, url.length) === url && src.match(/\/latest\.js(\?|$)/)) {
return scriptData(script, cdn);
}
}
return null;
}
/**
* @return {ScriptData} The data for the script tag that loaded latest.js
*/
function getScript(): ScriptData {
if (document.currentScript) {
return scriptData(document.currentScript as HTMLScriptElement);
}
const script = document.getElementById('MathJax-script') as HTMLScriptElement;
if (script && script.nodeName.toLowerCase() === 'script') {
return checkScript(script);
}
const scripts = document.getElementsByTagName('script');
for (const script of Array.from(scripts)) {
const data = checkScript(script);
if (data) {
return data;
}
}
return null;
}
/*=====================================================================*/
/**
* Save the version and date information in localStorage so we don't
* have to contact the CDN for every page that uses MathJax.
*
* @param {string} version The version to save
*/
function saveVersion(version: string) {
try {
const data = version + ' ' + Date.now();
localStorage.setItem(MJX_LATEST, data);
} catch (err) {}
}
/**
* Get the version from localStorage, and make sure it is fresh enough to use
*
* @return {string|null} The version string (if one has been saved) or null (if not)
*/
function getSavedVersion(): string | null {
try {
const [version, date] = localStorage.getItem(MJX_LATEST).split(/ /);
if (date && Date.now() - parseInt(date) < SAVE_TIME) {
return version;
}
} catch (err) {}
return null;
}
/*=====================================================================*/
/**
* Create a script tag that loads the given URL
*
* @param {string} url The URL of the javascript file to be loaded
* @param {string} id The id to use for the script tag
*/
function loadMathJax(url: string, id: string) {
const script = document.createElement('script');
script.type = 'text/javascript';
script.async = true;
script.src = url;
if (id) {
script.id = id;
}
const head = document.head || document.getElementsByTagName('head')[0] || document.body;
if (head) {
head.appendChild(script);
} else {
Error('Can\'t find the document <head> element');
}
}
/**
* When we can't find the current version, use the original URL but remove the "latest.js"
*/
function loadDefaultMathJax() {
if (script) {
loadMathJax(script.src.replace(/\/latest\.js\?/, '/'), script.id);
} else {
Error('Can\'t determine the URL for loading MathJax');
}
}
/**
* Load the given version using the base URL and file to load
* (if the versions differ, run latest.js from the new version
* in case there are important changes there)
*
* @param {string} version The version of MathJax to load from
*/
function loadVersion(version: string) {
if (script.version && script.version !== version) {
script.file = 'latest.js?' + script.file;
}
loadMathJax(script.cdn.base + version + script.dir + '/' + script.file, script.id);
}
/**
* Check if the given version is acceptable and load it if it is.
*
* @param {string} version The version to check if it is the latest (valid) one
* @return {boolean} True if it is the latest version, false if not
*/
function checkVersion(version: string): boolean {
const major = parseInt(version.split(/\./)[0]);
if (major === MJX_VERSION && !version.match(/-(beta|rc)/)) {
saveVersion(version);
loadVersion(version);
return true;
}
return false;
}
/*=====================================================================*/
/**
* Create an XMLHttpRequest object, if possible
*
* @return {XMLHttpRequest} The XMLHttpRequest instance
*/
function getXMLHttpRequest(): XMLHttpRequest {
if (window.XMLHttpRequest) {
return new XMLHttpRequest();
}
if (window.ActiveXObject) {
try { return new window.ActiveXObject('Msxml2.XMLHTTP'); } catch (err) {}
try { return new window.ActiveXObject('Microsoft.XMLHTTP'); } catch (err) {}
}
return null;
}
/**
* Request JSON data from a CDN. If it loads OK, call the action() function
* on the data. If not, or if the action returns false, run the failure() function.
*
* @param {CdnData} cdn The CDN whose API will be used
* @param {Function} action The function to perform when the data are received
* @param {Function} failure The function to perform if data can't be obtained,
* or if action() returns false
*/
function requestXML(cdn: CdnData, action: (json: JSON | JSON[]) => boolean, failure: () => void) {
const request = getXMLHttpRequest();
if (request) {
// tslint:disable-next-line:jsdoc-require
request.onreadystatechange = function () {
if (request.readyState === 4) {
if (request.status === 200) {
!action(JSON.parse(request.responseText)) && failure();
} else {
Error('Problem acquiring MathJax version: status = ' + request.status);
failure();
}
}
};
request.open('GET', cdn.api, true);
request.send(null);
} else {
Error('Can\'t create XMLHttpRequest object');
failure();
}
}
/**
* Look through the list of versions on GitHub and find the first one that
* has the MJX_VERSION as its major version number, and load that. If none
* is found, run the version from which latest.js was loaded.
*/
function loadLatestGitVersion() {
requestXML(GITHUB, (json: JSON[]) => {
if (!(json instanceof Array)) return false;
for (const data of json) {
if (checkVersion((data as any)[GITHUB.key])) {
return true;
}
}
return false;
}, loadDefaultMathJax);
}
/**
* Check the CDN for its latest version, and load that, if it is an
* acceptable version, otherwise, (e.g., the current version has a
* higher major version that MJX_VERSION), find the highest version on
* GitHub with the given major version and use that. If one can't be
* found, use the version where latest.js was loaded.
*/
function loadLatestCdnVersion() {
requestXML(script.cdn, function (json) {
if (json instanceof Array) {
json = json[0];
}
if (!checkVersion((json as any)[script.cdn.key])) {
loadLatestGitVersion();
}
return true;
}, loadDefaultMathJax);
}
/*=====================================================================*/
/**
* Find the script that loaded latest.js
* If the script is from a known CDN:
* Retrieve the cached version (if any)
* Load the given version of the file, if the version is cached,
* Otherwise find the latest version and load that.
* Otherwise,
* Load using the version where latest.js was loaded.
*/
export function loadLatest() {
script = getScript();
if (script && script.cdn) {
const version = getSavedVersion();
version ?
loadVersion(version) :
loadLatestCdnVersion();
} else {
loadDefaultMathJax();
}
}