How do I know the language, and the request software (browser) in Express?

When they make a request to my creator server in Express, and I try to know the language, and the browser software, with req.language and `req.software“ it gives me undefined

my current code is:

app.get('/api/whoami',  (req, res, next)=> {

    let json = {"ipaddress": req.ip, "language": req.language, "software":  req.software}

    res.json(json)

    next()
})

to see the complete code in more detail visit https://replit.com/@Michael-Liendo/boilerplate-project-headerparser

>Solution :

req.headers["user-agent"]        // browser info
req.headers["accept-language"]   // user's browser language