Sorry for the confusion. I think you could generate the memento each time you compile your blog into HTML. The memento can be stored as a json file and served statically by your fileserver. When a user visits your page, retrieve the memento from the server. Then, initialize the searcher with it. In this way you avoid indexing content at runtime.
As a bonus you could cache the memento in the local storage or session storage.
As a bonus you could cache the memento in the local storage or session storage.