any way to get user's latitude & longitude on web browser that is accurate?

I want to get user's location when he/she submits a form. I tried to use Google's navigator.geolocation.watchPosition but this returns incorrect data when website is accessed using computer machine. The code I used is given below:

var x = document.getElementById("demo");
function getLocation() {
    if (navigator.geolocation) {
        navigator.geolocation.watchPosition(showPosition);
    } else {
        x.innerHTML = "Geolocation is not supported by this browser.";
    }
}
function showPosition(position) {
    x.innerHTML = "Latitude: " + position.coords.latitude + 
    "<br>Longitude: " + position.coords.longitude; 
}

I want to know whether this is possible or not using any personal computer?

Else I'll try to provide a map where user can put/drag marker to his/her location (like displayed on this link: https://www.gps-coordinates.org/)

Thanks