Search lunr taken from https://github.com/projectpages/project-pages

search.js

---
---
jQuery(function() {
  // Initialize lunr with the fields to be searched, plus the boost.
  window.idx = lunr(function () {
    this.field('id');
    this.field('title');
    this.field('content', { boost: 10 });
    this.field('author');
    this.field('categories');
  });

  // Get the generated search_data.json file so lunr.js can search it locally.
  window.data = $.getJSON('{{ site.baseurl }}/search/search_data.json');

  // Wait for the data to load and add it to lunr
  window.data.then(function(loaded_data){
    $.each(loaded_data, function(index, value){
      window.idx.add(
        $.extend({ "id": index }, value)
      );
    });
  });

  // Event when the form is submitted
  $("#site_search").submit(function(event){
      event.preventDefault(); // RTH: per Google, preventDefault() might be the culprit in Firefox
      var query = $("#search_box").val(); // Get the value for the text field
      var results = window.idx.search(query); // Get lunr to perform a search
      display_search_results(results); // Hand the results off to be displayed
  });

  function display_search_results(results) {
    var $search_results = $("#search_results");

    // Wait for data to load
    window.data.then(function(loaded_data) {

      // Are there any results?
      if (results.length) {
        $search_results.empty(); // Clear any old results

        // Iterate over the results
        results.forEach(function(result) {
          var item = loaded_data[result.ref];

          // Build a snippet of HTML for this result
          var appendString = '<li><a href="' + item.url + '">' + item.title + '</a></li>';

          // Add the snippet to the collection of results.
          $search_results.append(appendString);
        });
      } else {
        // If there are no results, let the user know.
        $search_results.html('<li>No results found.<br/>Please check spelling, spacing, yada...</li>');
      }
    });
  }
});

search_data.json

---
layout: null
---
{
  {% for post in site.posts %}

    "{{ post.url | slugify }}": {
      "title": "{{ post.title | xml_escape }}",
      "content"	 : "{{post.content | strip_html | strip_newlines | remove:  "	" | escape | remove: "\"}}",
      "url": "{{ site.baseurl }}{{ post.url | xml_escape }}",
      "author": "{{ post.author | xml_escape }}",
      "categories": "{% for category in post.categories %}{{ category }}{% unless forloop.last %}, {% endunless %}{% endfor %}"
    }
    {% unless forloop.last %},{% endunless %}
  {% endfor %}

  {% for page in site.pages %}
    {% if page.url == '/speaking/index.html' or page.url == '/if-rudyard-kipling/index.html' or page.url == '/about/index.html' or page.url == '/contact/index.html' or page.url == '/sudo-disclaimer/index.html' %}
      ,

      "{{ page.url | slugify }}":  {
        "title": "{{ page.title | xml_escape }}",
      "content"	 : "{{page.content | strip_html | strip_newlines | remove:  "	" | escape | remove: "\"}}",
        "url": "{{ site.baseurl }}{{ page.url | xml_escape }}"
      }
    {% endif %}
  {% endfor %}
}

<!-- Search lunr taken from https://github.com/projectpages/project-pages -->
<script type="text/javascript" async defer src="https://cdnjs.cloudflare.com/ajax/libs/lunr.js/0.7.0/lunr.min.js"></script>

<!-- custom js file for lunr 0.7.0 -->
<script type="text/javascript" async defer src="/js/search.js"></script>

<------ in body tag ------>

<h3 class="no-anchor">Search</h3>
<form action="get" id="site_search" autocomplete="on">
 <strong>By keyword or tag:</strong><br />
 <input style="font-size:20px;" type="text" id="search_box">
 <input style="font-size:20px;font-weight: bold;" type="submit" value="Search">
 </form>
 <br />
                                    
 <ul id="search_results"></ul>

<-------------- somewhere in html page / post ------------------>

this only runs with lunr version 0.7.0 as far as I know...
https://lunrjs.com/

Files are separate (I couldn't combine them inside the js folder in custom js, for some reason)...

Works! But is maybe Old...

Updated... Works in Custom.js (search.js fits under doc-ready...)

$(document).ready(function(){
    // Responsive video embeds
    $('.entry-content').fitVids();




// Initialize lunr with the fields to be searched, plus the boost.
window.idx = lunr(function () {
    this.field('id');
    this.field('title');
    this.field('content', { boost: 10 });
    this.field('author');
    this.field('categories');
  });

  // Get the generated search_data.json file so lunr.js can search it locally.
  window.data = $.getJSON('/js/search_data.json');

  // Wait for the data to load and add it to lunr
  window.data.then(function(loaded_data){
    $.each(loaded_data, function(index, value){
      window.idx.add(
        $.extend({ "id": index }, value)
      );
    });
  });

  // Event when the form is submitted
  $("#site_search").submit(function(event){
      event.preventDefault(); // RTH: per Google, preventDefault() might be the culprit in Firefox
      var query = $("#search_box").val(); // Get the value for the text field
      var results = window.idx.search(query); // Get lunr to perform a search
      display_search_results(results); // Hand the results off to be displayed
  });

  function display_search_results(results) {
    var $search_results = $("#search_results");

    // Wait for data to load
    window.data.then(function(loaded_data) {

      // Are there any results?
      if (results.length) {
        $search_results.empty(); // Clear any old results

        // Iterate over the results
        results.forEach(function(result) {
          var item = loaded_data[result.ref];

          // Build a snippet of HTML for this result
          var appendString = '<li><a href="' + item.url + '">' + item.title + '</a></li>';

          // Add the snippet to the collection of results.
          $search_results.append(appendString);
        });
      } else {
        // If there are no results, let the user know.
        $search_results.html('<li>No results found.<br/>Please check spelling, spacing, yada...</li>');
      }
    });
  }

make sure {{ site.baseurl }} is gone... in window-data

This code works up to version 1.0.0 Lunr. JS

http://rayhightower.com/blog/2016/01/04/how-to-make-lunrjs-jekyll-work-together/

Want a Better Search? Take a look at this one... (It is Better than LunrJS!)...

https://github.com/christian-fei/Simple-Jekyll-Search
https://blog.webjeda.com/instant-jekyll-search/

https://gist.github.com/manbearwolf/f86195a237ba5d8f5d5f67e147acdbe1