meteor geolocation/maps excerpt (part of https://medium.com/p/adf3c3d1ebc6 tutorial)

main.js

Template.map.onCreated(function(){
  var self = this
  GoogleMaps.ready('map', function(map) {
    self.autorun(function(){
      self.map = map
      plotAllUsers.bind(self)()
      var user = Meteor.user()
      if (user) {
        setupReactiveVarsAndGetCoords(user).then(function(coords){
          [latitudeVal, longitudeVal] = coords
          Meteor.call("updateUser", {
            _id: user._id, latitude: latitudeVal, longitude: longitudeVal
          })
        }).catch(function(err){ console.log("Geolocation not loaded") })
      } else { console.log("Not pinging server, not signed in") }
    })
  });
})


// when called, is bound to a custom "this" object
function plotAllUsers() {
  Meteor.users.find(
    {}, { fields: { latitude: 1, longitude: 1, emails: 1 } }
  ).forEach(function(user){
    if (!(this.markers)) { this.markers = {} }
    if (!(this.markers[user._id])) {
      if (user.latitude && user.longitude) {
        this.markers[user._id] = new google.maps.Marker({
          position: new google.maps.LatLng(user.latitude, user.longitude),
          map: this.map.instance
        });
      }
    } else {
      this.markers[user._id].setPosition({lat: user.latitude, lng: user.longitude})
    }
  }.bind(this))
}

function setupReactiveVarsAndGetCoords(user) {
  var latLng = Geolocation.latLng();
  if (! latLng) { return Promise.reject(); }
  if (!window.lat || !window.lng) {
    window.lat = new ReactiveVar(latLng.lat), window.lng = new ReactiveVar(latLng.lng)
  }
  if (!(window.geolocationRandomnessInterval)) {
    window.geolocationRandomnessInterval = window.setInterval(function() {
      window.lat.set(Math.random() * 50)
      window.lng.set(Math.random() * 50)
    }, 1000)
  }
  console.log("coords changed")
  return Promise.resolve([window.lat.get(), window.lng.get()])
}