refactor: Move the tracking model into commons

frontend/src/pages/level.tsx

@@ -20,6 +20,9 @@ import { withRouter } from "react-router-dom";
 
 import VocabularyData from "../components/VocabularyData";
 
+import { TrackerEvent } from "../models/tracker";
+import { trackAction } from "../api/tracker";
+
 import { IVocab, VocabType } from "../models/vocab";
 
 interface IProps {
@@ -100,6 +103,10 @@ const LevelPageWithRouter = withRouter(
         }
 
         cancelLevel = () => {
+            // Track the cancellation of a level
+            trackAction(TrackerEvent.CANCEL_LEARNING);
+
+            // Close the dialog and go to the dashboard
             this.closeLeave();
             this.props.history.push("/dashboard");
         }

frontend/src/pages/review.tsx

@@ -27,6 +27,9 @@ import {
 } from "../models/vocab";
 import { ReviewType, IReviewMetadata } from "../models/review";
 
+import { TrackerEvent } from "../models/tracker";
+import { trackAction } from "../api/tracker";
+
 //@ts-ignore
 import lev from "js-levenshtein";
 import {
@@ -104,16 +107,7 @@ const ReviewPageWithRouter = withRouter(
             }[reviewType];
 
             // Track the start of a session
-            fetch(`${BACKEND_URL}/api/tracker`, {
-                headers: new Headers({
-                    "Content-Type": "application/json",
-                }),
-                method: "POST",
-                body: JSON.stringify({
-                    session: window.sessionStorage.getItem("tracker_session"),
-                    event: "START_LEARNING",
-                }),
-            });
+            trackAction(TrackerEvent.START_LEARNING);
 
             getVocab().then((res: IVocab[]) => {
                 // Check if we received any vocabulary
@@ -158,16 +152,7 @@ const ReviewPageWithRouter = withRouter(
             this.closeDialog();
 
             // Track the cancellation of a learning session
-            fetch(`${BACKEND_URL}/api/tracker`, {
-                headers: new Headers({
-                    "Content-Type": "application/json",
-                }),
-                method: "POST",
-                body: JSON.stringify({
-                    session: window.sessionStorage.getItem("tracker_session"),
-                    event: "CANCEL_LEARNING",
-                }),
-            });
+            trackAction(TrackerEvent.CANCEL_LEARNING);
 
             // Show the drawer button again
             this.props.drawerButtonState(true);