How to find out YouTube 'auto subtitle language' with JavaScript? (get auto captions language)

Question

1. I developed YouTube subtitle extraction.
   My program fetches subtitles for 'user selected language'.

2. However, there were so many languages ??to choose from.

3. So, I used the link below to get the 'subtitles language list of for the video'.
   http://video.google.com/timedtext?v=${youtubeID}&type=list
   http://video.google.com/timedtext?v=oIa3BFBHJFI&type=list (example)

my code:

        fetch(`http://video.google.com/timedtext?v=${youtubeID}&type=list`
        .then(res => res.text())                                                 // 1. xml -> get text
        .then(str => (new window.DOMParser()).parseFromString(str, "text/xml"))  // 2. text -> xml
        .then(data => {
            let tempLanguageList = [];
            let xml = data.getElementsByTagName("transcript_list")[0];          

            // get language
            for (let i = 0; i < xml.childElementCount; i++) {
                let item = xml.children.item(i);   // ??: <track id=?"22" name lang_code=?"en" lang_original=?"English" lang_translated=?"English" lang_default=?"true">?</track>?
                let itemObject = item.getAttribute("lang_code") + ", " + item.getAttribute("lang_original")
                tempLanguageList.push(itemObject);  // ex) en
            }

            console.log("tempLanguageList: ", tempLanguageList);
        })

result:

4. However, the automatic subtitles were not displayed in the link above.

(add) For example, https://youtu.be/D_M9fl_Cj9I in this video,'english' is an automatic subtitle and 'korea' is a manual subtitle.

But when I check it, english did not appear on the list.
http://video.google.com/timedtext?v=D_M9fl_Cj9I&type=list

[question]
How can I check the 'language list of automatic subtitles' for a specific YouTube video?

question from:https://stackoverflow.com/questions/65895932/how-to-find-out-youtube-auto-subtitle-language-with-javascript-get-auto-capt

Answer 1

Waitting for answers