Add web front-end and fix API issues

node_modules/rxjs/dist/esm/internal/operators/switchScan.js

@@ -0,0 +1,12 @@
+import { switchMap } from './switchMap';
+import { operate } from '../util/lift';
+export function switchScan(accumulator, seed) {
+    return operate((source, subscriber) => {
+        let state = seed;
+        switchMap((value, index) => accumulator(state, value, index), (_, innerValue) => ((state = innerValue), innerValue))(source).subscribe(subscriber);
+        return () => {
+            state = null;
+        };
+    });
+}
+//# sourceMappingURL=switchScan.js.map