Vue cli serve, how to get a httprequest with success (404 file not found)

I have a vue app. I have a ‘vue cli serve’ command that compiles the app and serves the application
(Using a webpack node server as far as I know)

I want to get a file using XMLHttpRequest

Ok, I want to retrieve a file using:

var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
      if (this.readyState == 4 && this.status == 200) {
       debugger
        this.responseText;
      }
    };
    xhttp.open("GET", file, true);
    xhttp.send();

ok i have played with a lot of combinations for:

http://192.168.0.2:8080//
http://localhost:8080//

and different folders and existing files without success.
I have allways the error: ( or similar)

 GET http://192.168.0.2:8080/public/web_icon.txt 404 (Not Found)

Any idea of to fix this ?
Thanks in advance