mercator.js

// license: BSD3
const WEBMERCATOR_R = 6378137.0;
const DIAMETER = WEBMERCATOR_R * 2 * Math.PI;
class Mercator {
  static project(lon, lat) {
    var x = DIAMETER * lon/360.0;
    var sinlat = Math.sin(lat * Math.PI/180.0);
    var y = DIAMETER *Math.log((1+sinlat)/(1-sinlat)) / (4*Math.PI);
    return { x, y };
  }
}