How to get HTTP user-agent header with js?

Question

For my project, I want to get and print the user-agent of my browser. I'm using javascript (with node) to accomplish my goal. How can I get and print the user-agent header without using the HTTP module and html if possible and inside of this blank function:

function userAgent() {
  
}

[window.navigator.userAgent](https://developer.mozilla.org/en-US/docs/Web/API/Window/navigator) — mplungjan, Jul 29 '20 at 07:02
Do you want to know what kind of browser users are accessing? — Minwoo Kim, Jul 29 '20 at 07:03

score 5 · Answer 1 · answered Jul 29 '20 at 06:59

5

Just use window.navigator.userAgent

function userAgent() {
  return window.navigator.userAgent;
}

console.log(userAgent());

answered Jul 29 '20 at 06:59

Sebastian Kaczmarek

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I get this error: ` return window.navigator.userAgent;` `^` `ReferenceError: window is not defined` I should clarify that I also don't want to use html for this – Sergio Ley Jul 29 '20 at 07:04
How do you run this code? Are you using Node maybe? – Sebastian Kaczmarek Jul 29 '20 at 07:13
I am using node – Sergio Ley Jul 29 '20 at 07:14
2

Well, then you should definitely clarify that in the question because that changes like everything. You cannot get a user agent in the Node app itself because UA is something tightly connected with a **client app**. You could do that if you had for example some frontend app that makes a request to your Node server - then you can get the UA header **from the request**. – Sebastian Kaczmarek Jul 29 '20 at 07:17
You have reference this article https://stackoverflow.com/questions/6163350/server-side-browser-detection-node-js – Minwoo Kim Jul 29 '20 at 07:24

score 1 · Accepted Answer · answered Jul 29 '20 at 07:11

You can try this.

<script>
   window.onload = function () {
        var agent = navigator.userAgent.toLowerCase();
        if (agent.indexOf('chrome') != -1) { 
           alert('Chrome');
        }
        if (agent.indexOf('msie') != -1) {
           alert('Explorer');
        }
        if (agent.indexOf('safari') != -1) {
           alert('Safari');
        }
        if (agent.indexOf('firefox') != -1) {
           alert('Firefox');
        }
   }
</script>

How to get HTTP user-agent header with js?

2 Answers2