Get total read word count for language

get_total_word_count.js

await fetch(`https://readlang.com/api/books?language=${lang}&firstLanguage=en&public=true`, {
    "credentials": "include",
    "headers": {
        "Accept": "application/json, text/javascript, */*; q=0.01",
        "X-Requested-With": "XMLHttpRequest",
    },
    "referrer": "https://readlang.com/ja/library",
    "method": "GET",
    "mode": "cors"
})
    .then(res => res.json())
    .then(books =>
        books.filter(book => book.userBook?.tags?.includes('completed'))
            .map(book => book.totalWords)
            .reduce((a, b) => a + b, 0)
    );