Whenever the Google Maps API needs to translate a location in the world to a location on a map (the screen), it needs to first translate latitude and longitude values into a "world" coordinate. This translation is accomplished using the Mercator projection.
More details can be found here.
Ported from here.
$ npm install -g mercator-projection
The following examples show you how to use mercator-projection.
var merc = require('mercator-projection');
// translate a latlng to a xy
var xy = merc.fromLatLngToPoint({lat: -27.470127, lng: 153.0147027});
// {x: 236.81045525333332, y: 148.32879785796487}
// translate a xy to a latlng
var ll = merc.fromPointToLatLng({x: 236.81045525333332, y: 148.32879785796487})
// ~ {lat: -27.470127, lng: 153.0147027}$ npm test