starting SymptomVsSymptomChartDataProviderTest

docs/SymptomsCausedByCOVIDLots/js/Sets.js

@@ -0,0 +1,20 @@
+class Sets {
+
+    static filterSet(set, predicate) {
+        return new Set([...set].filter(predicate));
+    }
+
+    static union(sets) {
+        return sets.reduce(
+            (union, set) => new Set([...union, ...set]),
+            new Set());
+    }
+
+    static intersection(set1, set2) {
+        return new Set([...set1].filter(x => set2.has(x)));
+    }
+
+    static isEmpty(set) {
+        return set.size == 0;
+    }
+}

docs/SymptomsCausedByCOVIDLots/js/SymptomVsSymptomChartDataProvider.js

@@ -0,0 +1,28 @@
+class SymptomVsSymptomChartDataProvider {
+
+    static retainCommonLots({ prrByLotX, prrByLotY }) {
+        const commonLots = SymptomVsSymptomChartDataProvider.#getCommonKeys(prrByLotX, prrByLotY);
+        return {
+            prrByLotX: SymptomVsSymptomChartDataProvider.#retainKeysOfDict(prrByLotX, commonLots),
+            prrByLotY: SymptomVsSymptomChartDataProvider.#retainKeysOfDict(prrByLotY, commonLots)
+        };
+    }
+
+    static #getCommonKeys(dict1, dict2) {
+        return Sets.intersection(
+            SymptomVsSymptomChartDataProvider.#getKeySet(dict1),
+            SymptomVsSymptomChartDataProvider.#getKeySet(dict2));
+    }
+
+    static #getKeySet(dict) {
+        return new Set(Object.keys(dict));
+    }
+
+    static #retainKeysOfDict(dict, keys2Retain) {
+        const entries2Retain =
+            Object
+                .entries(dict)
+                .filter(([key, _]) => keys2Retain.has(key));
+        return Object.fromEntries(entries2Retain);
+    }
+}

docs/SymptomsCausedByCOVIDLots/js/SymptomVsSymptomChartView.js

@@ -14,13 +14,13 @@ class SymptomVsSymptomChartView {
         // FK-TODO: fetch multiple files: https://stackoverflow.com/a/31711496 or https://stackoverflow.com/a/53892713
         PrrByVaccineProvider.getPrrByVaccine(symptom1)
             .then(
-                prrByKey1 => {
+                prrByLot1 => {
                     PrrByVaccineProvider.getPrrByVaccine(symptom2)
                         .then(
-                            prrByKey2 => {
+                            prrByLot2 => {
                                 const myData =
                                     Object
-                                        .values(prrByKey2)
+                                        .values(prrByLot2)
                                         .map(
                                             val =>
                                             ({