Add basic version of Comments component

app/javascript/reducers/commentReducer.ts

@@ -0,0 +1,32 @@
+import {
+  COMMENT_REQUEST_SUCCESS,
+} from '../actions/requestComment';
+
+import IComment from '../interfaces/IComment';
+
+const initialState: IComment = {
+  id: 0,
+  body: '',
+  userFullName: '',
+  updatedAt: '',
+};
+
+const commentReducer = (
+  state = initialState,
+  action,
+): IComment => {
+  switch (action.type) {
+    case COMMENT_REQUEST_SUCCESS:
+      return {
+        id: action.comment.id,
+        body: action.comment.body,
+        userFullName: action.comment.user_full_name,
+        updatedAt: action.comment.updated_at,
+      };
+
+    default:
+      return state;
+  }
+}
+
+export default commentReducer;