How to get user's geolocation?

Question

On many sites I saw printed out my current city where I am (eg \"Hello to Berlin.\"). How they do that? What everything is needed for that? I guess the main part is here jav

Answer 1

If you prefer to use ES6 and promises here is another version

function getPositionPromised() {
  function successCb(cb) {
    return position => cb(position);
  }

  function errorCb(cb) {
    return () => cb('Could not retrieve geolocation');
  }

  return new Promise((resolve, reject) => {
    if (window.navigator.geolocation) {
      navigator.geolocation.getCurrentPosition(successCb(resolve), errorCb(reject));
    } else {
      return reject('No geolocation support');
    }
  })
}

And you can use it like this:

getPositionPromised()
  .then(position => {/*do something with position*/})
  .catch(() => {/*something went wrong*/})

Answer 2

Internet Service Providers buy up big chunks of IP addresses, so what you're most likely seeing is a backtrace your IP to a known ISP. They have a database with ISP's and their location in the world, so they can try to see where you're from. You could try to use a site like http://www.ipaddresslocation.org/ to do your work. If you look around, there is bound to be a site that lets you enter an IP and get a location, so you just send a POST request to that site with your visitor's IP and scrape the location from the response.

Alternatively you could try to look for an ISP database that has location and what chunks of the IP range they have been allocated. You could probably find one for money, but a free one might be harder to find. Alternatively, check out this free database http://www.maxmind.com/app/geolite

Answer 3

You need a browser which supports the geolocation api to obtain the location of the user (however, you need the user's consent (an example here) to do so (most newer browsers support that feature, including IE9+ and most mobile OS'es browsers, including Windows Phone 7.5+).

all you have to do then is use JavaScript to obtain the location:

if (window.navigator.geolocation) {
    var failure, success;
    success = function(position) {
      console.log(position);
    };
    failure = function(message) {
      alert('Cannot retrieve location!');
    };
    navigator.geolocation.getCurrentPosition(success, failure, {
      maximumAge: Infinity,
      timeout: 5000
    });
}

The positionobject will hold latitude and longitude of the user's position (however this can be highly inaccurate in less densely populated areas on desktop browsers, as they do not have a GPS device built in). To explain further: Here in Leipzig in get an accuracy of about 300 meters on a desktop computer - i get an accuracy of about 30 meters with my cell phone's GPS device.

You can then go on and use the coordinates with the Google Maps API (see here for reverse geocoding) to lookup the location of the user. There are a few gems for Rails, if you want. I never felt the need to use them, but some people seem to like them.

As for a list of countries/cities, we used the data obtainable from Geonames once in a project, but we needed to convert it for our needs first.

Answer 4

I've found getCurrentPosition() to often be inaccurate since it doesn't spend a lot of time waiting on the GPS to acquire a good accuracy. I wrote a small piece of JavaScript that mimics getCurrentPosition() but actually uses watch position and monitors the results coming back until they are better accuracy.

Here's how it looks:

navigator.geolocation.getAccurateCurrentPosition(onSuccess, onError, {desiredAccuracy:20, maxWait:15000});

Code is here - https://github.com/gwilson/getAccurateCurrentPosition

Answer 5

Here is an another api to find out the location in PHP,

http://ipinfodb.com/ip_location_api.php

Answer 6

Correc syntax would be :

navigator.geolocation.getCurrentPosition(successCallBack, failureCallBack);

Use :

    navigator.geolocation.getCurrentPosition(
        function(position){
            var latitude  = position.coords.latitude;
            var longitude = position.coords.longitude;
            console.log("Latitude : "+latitude+" Longitude : "+longitude);
        },
        function(){
            alert("Geo Location not supported");
        }
    );