I have been using Google Programmable Search Engine to test search functionality on my blog, but I found that it doesn’t work quite as I expected. First, I tried Bing and DuckDuckGo as alternatives, but none of them performed as desired. DuckDuckGo’s API is nice, but it lacks a ‘site:’ filter, which prevented it from working as needed.

Here are the steps to set up a Jekyll search system using Lunr.js for GitHub Pages(github.io):

1. Create js/search.js and add this code
2. Add search.md to the root of your project.
3. Add an HTML form where you like

<li class="nav-item my-auto">
    <div class="header-search">
        <form class="header-search-form" action="/search.html" method="get">
            <input type="text" id="search-box" name="query">
            <input type="submit" value="search">
        </form>
    </div>
</li>

Check here for example.

If you have a page listing elsewhere and would like to remove it, refer to this conditional statement.