Access request object in Node (question)

[7ing7ing]

Hello there.

I am currently doing the headparser project from the API and Microservices.

Basically, I need to be able to access to ip, software and language of my computer.
So, I found that there is a lot of information in the request object. What I don´t understand is the way to access them.
My code:

// your first API endpoint...
app.get("/api/whoami", function (req, res) {
  res.json({
    ipaddress: req.ip,
    language: req.headers["accept-language"],
    software: req.headers["user-agent"],
  });
});

Request object:

Your app is listening on port 52643
{
  host: 'localhost:52643',
  connection: 'keep-alive',
  'sec-ch-ua': '"Chromium";v="94", "Google Chrome";v="94", ";Not A Brand";v="99"',
  'sec-ch-ua-mobile': '?0',
  'sec-ch-ua-platform': '"Windows"',
  'upgrade-insecure-requests': '1',
  'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.81 Safari/537.36',
  accept: 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9',
  'sec-fetch-site': 'none',
  'sec-fetch-mode': 'navigate',
  'sec-fetch-user': '?1',
  'sec-fetch-dest': 'document',
  'accept-encoding': 'gzip, deflate, br',
  'accept-language': 'es-ES,es;q=0.9,zh-ES;q=0.8,zh;q=0.7,en-ES;q=0.6,en;q=0.5'
}
[nodemon] restarting due to changes...
[nodemon] starting `node server.js`
Your app is listening on port 51992

Why does this work?:

language: req.headers["accept-language"]
software: req.headers["user-agent"]

For me, it makes more sense if I do:

language: req.headers.accept["accept-language"]
software: req.headers.connection["user-agent"]

I mean, “headers” is an object, isn´t it? Why do I have to “skip” the “connection” or “accept” key in order to access the keys inside them?

[skaparate]

Hello!

@7ing7ing

I mean, “headers” is an object, isn´t it?

Yes, it’s an object. The thing, however, is that accept and connection are not properties of the object; the properties are accept-language and user-agent. The property connection is a direct child of the headers object, like this:

{
  connection: "...",
  "accept-header": "...",
  "user-agent": "..."
}

You may have confused them because they are in quotes. This is because the property names use the dash character.

[skaparate]

I made a mistake:

@skaparate

accept and connection are not properties of the object

This is not correct. connection is not a property of the object, but accept is. However, accept is not an object, but a string, so it doesn’t have any properties of it’s own.

[kevinSmith]

First of all, please don’t share pictures of code - cut and paste the code.

The thing, however, is that accept and connection are not properties of the object; the properties are accept-language and user-agent .

Maybe I’m misunderstanding. What I see is that req.headers is an object, the object that is logged out. I think what is confusing (as pointed out by skaparate) is that the property names look weird - the property names that are valid JS identifiers are white and property names that are not (in this case with a “-”) are in green and with quotes. But all those properties are on the same level. So, req.headers.accept is a sibling of req.headers[“accept-language”], not the parent. There is no nesting in his object. It is all just key/value pairs and all the values are strings.

If you want to reveal the hierarchy a bit better, you can do:

console.log(JSON.stringify(req.headers, null, 2));

That will convert the object into a string that represents the object like we’re use to seeing in code, with an indent of 2.

[7ing7ing]

Sorry, I removed the screenshot and used code instead.

@skaparate @kevinSmith I understood what you meant, thanks! The difference of the colours confused me and made me think they were nested.