Search Options for Static Websites
Here are some options for adding search and/or filters to your static website. These have various approaches, costs and ease of implementation.
Lunr.js (plugins: Jeyll, Metalsmith)
The less-technically inclined may want to look at something like Swiftype (paid, but has a limited free option), Tapir or Tipue. I use List.js extensively for filtering and recommend it highly.