Fix race condition in data fetching

src/App.js

@@ -3,16 +3,10 @@ import { Map } from 'immutable';
 
 import PointMap from './PointMap.js';
 import './App.css';
-import { get_lam_points, connect_lam_ws, get_lam_station_data } from './utils/api-client.js';
+import { get_lam_points, connect_lam_ws } from './utils/api-client.js';
 
 class App extends Component {
 
-  set_lam_points(lam_points) {
-    this.setState((prevState) => {
-      return { ...prevState, lam_points };
-    });
-  }
-
   update_state(fn) {
     this.setState((prevState) => {
       return fn(prevState);
@@ -33,8 +27,7 @@ class App extends Component {
     let width = window.innerWidth;
     let height = window.innerHeight;
     this.state = { lam_points: Map(), mapSize: { width, height } };
-    get_lam_points("http://tie.digitraffic.fi", this.set_lam_points.bind(this));
-    get_lam_station_data("http://tie.digitraffic.fi", this.update_state.bind(this));
+    get_lam_points("http://tie.digitraffic.fi", this.update_state.bind(this));
     connect_lam_ws("ws://tie.digitraffic.fi", this.update_state.bind(this));
     this.handleResize = this.handleResize.bind(this);
   }

src/utils/api-client.js

@@ -3,7 +3,7 @@ import { Map } from 'immutable';
 import LamStation from './lam-station.js';
 
 export function get_lam_points(api_url, set_state) {
-  fetch(`${api_url}/api/v1/metadata/tms-stations`)
+  return fetch(`${api_url}/api/v1/metadata/tms-stations`)
     .then((res) => res.json())
     .then((json) => {
       let stations = Map();
@@ -13,13 +13,17 @@ export function get_lam_points(api_url, set_state) {
         let station = new LamStation(id, coordinates, 0, 0);
         stations = stations.set(id, station);
       }
-      set_state(stations);
+      set_state((prevState) => {
+        const lam_points = stations;
+        return { ...prevState, lam_points };
+      });
     })
+    .then(() => get_lam_station_data(api_url, set_state))
     .catch(e => (console.error(e)));
 }
 
 export function get_lam_station_data(api_url, set_state) {
-  fetch(`${api_url}/api/v1/data/tms-data`)
+  return fetch(`${api_url}/api/v1/data/tms-data`)
     .then((res) => res.json())
     .then((json) => {
       set_state((prevState) => {