Add web front-end and fix API issues

node_modules/rxjs/dist/cjs/internal/operators/findIndex.js

@@ -0,0 +1,10 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.findIndex = void 0;
+var lift_1 = require("../util/lift");
+var find_1 = require("./find");
+function findIndex(predicate, thisArg) {
+    return lift_1.operate(find_1.createFind(predicate, thisArg, 'index'));
+}
+exports.findIndex = findIndex;
+//# sourceMappingURL=findIndex.js.map