Over Christmas, I made a full text search engine. You can read my article for more details.
This is currently used on this website. To try it out, search using the box on the front page.
Now, you can easily set up a API endpoint for search on your website, powered by Kvarn.
you can add a search engine to Kvarn and customize it.
See these two lines from the reference implementation for an example on how to set it up.
This will index all the pages of the site (except those provided by PrepareFn).
Check out the WordPress integration here.
This function handles the searching in JS.
This HTML is the search bar.
And this is the styling.