Youtube double language subtitle / Youtube 双语字幕. 如果不能自动加载，请关闭字幕再次打开即可。默认语言为浏览器首选语言。已知Bug：默认为zh-TW繁体中文时，即使请求简体中文翻译，Youtube依旧会返回繁体，已向 Youtube 提交 Issue，有新动向此处代码也会同步修改。
当前为
// ==UserScript==
// @name Youtube double language subtitle / Youtube 双语字幕
// @version 1.1
// @description Youtube double language subtitle / Youtube 双语字幕. 如果不能自动加载，请关闭字幕再次打开即可。默认语言为浏览器首选语言。已知Bug：默认为zh-TW繁体中文时，即使请求简体中文翻译，Youtube依旧会返回繁体，已向 Youtube 提交 Issue，有新动向此处代码也会同步修改。
// @author Coink
// @match https://www.youtube.com/watch*
// @require https://unpkg.com/xhook@latest/dist/xhook.min.js
// @grant none
// @namespace https://github.com/CoinkWang/Y2BDoubleSubs
// ==/UserScript==
(function() {
// let localeLang = 'en' // or comment the upper line and define the language you wish here
let localeLang = navigator.language ? navigator.language : 'en'
xhook.after(function (request, response) {
if (request.url.includes('/api/timedtext') && !request.url.includes('&translate_h00ked')) {
let xhr = new XMLHttpRequest();
// Use RegExp to clean '&tlang=...' in our xhr request params while using Y2B auto translate.
let reg = new RegExp("(^|[&?])tlang=([^&]*)",'g');
xhr.open('GET', `${request.url.replace(reg,'')}&tlang=${localeLang}&translate_h00ked`, false);
xhr.send();
let defaultJson = null, localeJson = null;
if (response.data && JSON.parse(response.data).events){
defaultJson = JSON.parse(response.data)
}
localeJson = JSON.parse(xhr.response)
// Merge default subs with locale language subs
if (defaultJson.events.length === localeJson.events.length) {
// when length of segments are the same
for (let i = 0,len = defaultJson.events.length; i<len; i++) {
defaultJson.events[i].segs[0].utf8 += ('\n' + localeJson.events[i].segs[0].utf8)
response.text = JSON.stringify(defaultJson)
}
} else {
// when length of segments are not the same (e.g. automatic generated english subs)
let pureEvents = defaultJson.events.filter(event => event.aAppend !== 1 && event.segs)
for (let i = 0,len = localeJson.events.length; i<len; i++) {
let currentLocaleEvent = localeJson.events[i]
let currentRawEvents = pureEvents.filter(pe => currentLocaleEvent.tStartMs <= pe.tStartMs && pe.tStartMs < currentLocaleEvent.tStartMs + currentLocaleEvent.dDurationMs)
let s = '';
currentRawEvents.forEach(ev => ev.segs.forEach(seg => s += seg.utf8))
localeJson.events[i].segs[0].utf8 = s + '\n' + localeJson.events[i].segs[0].utf8
response.text = JSON.stringify(localeJson)
}
}
}
});
})();