My app is made with HTML/CSS and has 350+ HTML pages. There is no search capability. What are people doing to add search functionality to their mobile apps?

To clarify, the user should be able to go to a search page, type in a term, and the engine gives links to all the pages where that term appears. Ideally it should show the term in context, maybe even display the page name it's found on. I imagine it would be via Javascript, but I don't know. This should work on any mobile devices the use apps made from HTML/CSS/JS.

What are our options for adding even rudimentary search functionality? Please supply any URLs to the code or service.