add all frontend files

node_modules/rc-util/lib/React/isFragment.js

@@ -0,0 +1,25 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault").default;
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = isFragment;
+var _typeof2 = _interopRequireDefault(require("@babel/runtime/helpers/typeof"));
+var REACT_ELEMENT_TYPE_18 = Symbol.for('react.element');
+var REACT_ELEMENT_TYPE_19 = Symbol.for('react.transitional.element');
+var REACT_FRAGMENT_TYPE = Symbol.for('react.fragment');
+
+/**
+ * Compatible with React 18 or 19 to check if node is a Fragment.
+ */
+function isFragment(object) {
+  return (
+    // Base object type
+    object && (0, _typeof2.default)(object) === 'object' && (
+    // React Element type
+    object.$$typeof === REACT_ELEMENT_TYPE_18 || object.$$typeof === REACT_ELEMENT_TYPE_19) &&
+    // React Fragment type
+    object.type === REACT_FRAGMENT_TYPE
+  );
+}