Get the distance between two points in meters

distance-geolocation.js

function getDistance(p1, p2) {
  var radlat1 = Math.PI * p1.lat/180;
  var radlat2 = Math.PI * p2.lat/180;
  var theta = p1.lng - p2.lng;
  var radtheta = Math.PI * theta/180;
  var dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
  dist = Math.acos(dist);
  dist = dist * 180 / Math.PI;
  dist = dist * 60 * 1.1515 * 1.609344 * 1000;
  return dist;
}