browser version - expressjs / morgan - node.js

Question

I need to collect the user access log in the application, mainly the name and version of the browser he is using. However, morgan is bringing many details that I don't need, can you help me?
Currently:
Firefox
::1 - OPTIONS - /signin - 204 - 0 - 0.126 ms http://localhost:8080/auth - Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:76.0) Gecko/20100101 Firefox/76.0 -
Chrome
::1 - POST - /signin - 200 - 545 - 106.758 ms http://localhost:8080/auth - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36 -
::1 - OPTIONS - /signin - 204 - 0 - 0.163 ms http://localhost:8080/auth - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36 -
Expected:
Firefox
::1 - OPTIONS - /signin - 204 - 0 - 0.126 ms http://localhost:8080/auth - Firefox/76.0 -
Chrome
::1 - POST - /signin - 200 - 545 - 106.758 ms http://localhost:8080/auth -
Chrome/83.0.4103.61 -
My code:
app.use((req,res,next) => {
const logger = morgan(function (tokens, req, res) {
return [
tokens['remote-addr'](req, res), '-',
tokens.method(req, res), '-',
tokens.url(req, res), '-',
tokens.status(req, res), '-',
tokens.res(req, res, 'content-length'), '-',
tokens['response-time'](req, res), 'ms',
tokens.referrer(req, res), '-',
tokens['user-agent'](req, res), '-',
].join(' ')
})
logger(req,res,next)
})

Answer 1

var result = accessLogEntry.replace(/(?<=auth\s-\s).*(?=(?:Firefox|Chrome)\/[\d\.]+)/g, "");
This takes care of most of your problem. In your 2nd chrome example it will leave both the Chrome and Safari versions listed. You'll need to determine which one is the correct browser. This will trim out all the garbage in the middle of the log entry.
Demo

Answer 2

I'm use a component called:
app.use(require('express-useragent').express())
const navigator = req.useragent.browser