How can I detect browser details in NestJs/NodeJs

Question

I am trying to integrate device-detector npm module in my application in order to detect the browser details. For that I am using this module npm i device-detector-js

I have integrated as it is code snippet in my code.

Below is my code:

app.controller.ts

import { Controller, Get, Req } from '@nestjs/common';
import { AppService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

@Get()
getHello(@Req() req): string {
  console.log(req.headers);
  return this.appService.getHello();
  }
}

app.service.ts

import { Inject, Injectable } from '@nestjs/common';
import DeviceDetector = require("device-detector-js");

@Injectable()
export class AppService {
private readonly deviceDetector = new DeviceDetector();

getHello(): string {
const userAgent = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.81(Windows; Intel windows 8_8.1_10_11) Safari/537.36"; 
const result = this.deviceDetector.parse(userAgent);
console.log(JSON.stringify(result));
return 'Hello World!';
 }
}

Output

[Nest] 23300  - 12/04/2022, 1:26:55 pm     LOG [RouterExplorer] Mapped {/test, GET} route +2ms
[Nest] 23300  - 12/04/2022, 1:26:55 pm     LOG [NestApplication] Nest application successfully started +4ms
{
  host: 'localhost:3000',
  connection: 'keep-alive',
  'cache-control': 'max-age=0',
  'sec-ch-ua': '" Not A;Brand";v="99", "Chromium";v="98", "Google 
 Chrome";v="98"',
  'sec-ch-ua-mobile': '?0',
 'sec-ch-ua-platform': '"Windows"',
 dnt: '1',
'upgrade-insecure-requests': '1',
'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) 
 AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.82 Safari/537.36'
}

It's working but not giving correct info as I am using Windows but it's showing Macintosh. Why is this happening?

Answer 1

Just pass headers from controller into service, something like this:

// controller
getHello(@Req() req): string {
  console.log(req.headers);
  return this.appService.getHello(req.headers);
}

// service
getHello(headers: {'user-agent': string }): string {
  const userAgent = headers['user-agent']; 
  const result = this.deviceDetector.parse(userAgent);
  console.log(JSON.stringify(result));
  return 'Hello World!';
}