Hugo search with lunr

cd static/js
wget https://raw.githubusercontent.com/olivernn/lunr.js/master/lunr.js

<form id="search"
    action='{{ with .GetPage "/search" }}{{.Permalink}}{{end}}' method="get">
    <label hidden for="search-input">Search site</label>
    <input type="text" id="search-input" name="query"
    placeholder="Type here to search">
    <input type="submit" value="search">
</form>

{{ define "main" }}
{{ partial "search-form.html" . }}

<ul id="results">
    <li>
        Enter a keyword above to search this site.
    </li>
</ul>
{{ end }}

---
title: Search
---

<script>
window.store = {
    // You can specify your blog section only:
    {{ range where .Site.Pages "Section" "blog" }}
    // For all pages in your site, use "range .Site.Pages"
    // You can use any unique identifier here
    "{{ .Permalink }}": {
        // You can customize your searchable fields using any .Page parameters
        "title": "{{ .Title  }}",
        "tags": [{{ range .Params.Tags }}"{{ . }}",{{ end }}],
        "content": {{ .Content | plainify }}, // Strip out HTML tags
        "url": "{{ .Permalink }}"
    },
    {{ end }}
}
</script>
<!-- Include Lunr and code for your search function,
which you'll write in the next section -->
<script src="/js/lunr.js"></script>
<script src="/js/search.js"></script>

function displayResults (results, store) {
  const searchResults = document.getElementById('results')
  if (results.length) {
    let resultList = ''
    // Iterate and build result list elements
    for (const n in results) {
      const item = store[results[n].ref]
      resultList += '<li><p><a href="' + item.url + '">' + item.title + '</a></p>'
      resultList += '<p>' + item.content.substring(0, 150) + '...</p></li>'
    }
    searchResults.innerHTML = resultList
  } else {
    searchResults.innerHTML = 'No results found.'
  }
}

// Get the query parameter(s)
const params = new URLSearchParams(window.location.search)
const query = params.get('query')

// Perform a search if there is a query
if (query) {
  // Retain the search input in the form when displaying results
  document.getElementById('search-input').setAttribute('value', query)

  const idx = lunr(function () {
    this.ref('id')
    this.field('title', {
      boost: 15
    })
    this.field('tags')
    this.field('content', {
      boost: 10
    })

    for (const key in window.store) {
      this.add({
        id: key,
        title: window.store[key].title,
        tags: window.store[key].category,
        content: window.store[key].content
      })
    }
  })

  // Perform the search
  const results = idx.search(query)
  // Update the list with results
  displayResults(results, window.store)
}

cd static/js
wget https://raw.githubusercontent.com/olivernn/lunr.js/master/lunr.js


```toml
[outputFormats]
  [outputFormats.SearchIndex]
		baseName = 'search'
    mediaType = 'application/json'

[outputs]
  home = ['HTML', 'RSS', 'SearchIndex']

[
  {{- range $index, $page := .Site.RegularPages -}}
    {{- if gt $index 0 -}} , {{- end -}}
    {{- $entry := dict "uri" $page.RelPermalink "title" $page.Title -}}
    {{- $entry = merge $entry (dict "content" ($page.Plain | htmlUnescape)) -}}
    {{- $entry = merge $entry (dict "description" $page.Description) -}}
    {{- $entry = merge $entry (dict "categories" $page.Params.categories) -}}
    {{- $entry | jsonify -}}
  {{- end -}}
]

{{ define "main" }}

{{ partial "nav.html" . }}
<h1>{{ .Title }}</h1>

{{ partial "search-form.html" . }}

<ul id="results">
    <li>
        Enter a keyword above to search this site.
    </li>
</ul>

<div class="search-results"></div>

{{ end }}

---
title: Search
---

<form id="search" class="search" role="search">
  <input type="search" id="search-input" class="search-input">
</form>

<template id="search-result" hidden>
  <article class="content post">
    <h2 class="post-title"><a class="summary-title-link"></a></h2>
    <summary class="summary"></summary>
    <div class="read-more-container">
      <a class="read-more-link">Read More »</a>
    </div>
  </article>
</template>

<script src="/js/lunr.js"></script>
<script src="/js/lunr-search.js"></script>

window.addEventListener("DOMContentLoaded", function(event)
{
  var index = null;
  var lookup = null;
  var queuedTerm = null;

  var form = document.getElementById("search");
  var input = document.getElementById("search-input");

  form.addEventListener("submit", function(event)
  {
    event.preventDefault();

    var term = input.value.trim();
    if (!term)
      return;

    startSearch(term);
  }, false);

  function startSearch(term)
  {
    // Start icon animation.
    form.setAttribute("data-running", "true");

    if (index)
    {
      // Index already present, search directly.
      search(term);
    }
    else if (queuedTerm)
    {
      // Index is being loaded, replace the term we want to search for.
      queuedTerm = term;
    }
    else
    {
      // Start loading index, perform the search when done.
      queuedTerm = term;
      initIndex();
    }
  }

  function searchDone()
  {
    // Stop icon animation.
    form.removeAttribute("data-running");

    queuedTerm = null;
  }

  function initIndex()
  {
    var request = new XMLHttpRequest();
    request.open("GET", "/search.json");
    request.responseType = "json";
    request.addEventListener("load", function(event)
    {
      lookup = {};
      index = lunr(function()
      {
        // Uncomment the following line and replace de by the right language
        // code to use a lunr language pack.

        // this.use(lunr.de);

        this.ref("uri");

        // If you added more searchable fields to the search index, list them here.
        this.field("title");
        this.field("content");
        this.field("description");
        this.field("categories");

        for (var doc of request.response)
        {
          this.add(doc);
          lookup[doc.uri] = doc;
        }
      });

      // Search index is ready, perform the search now
      search(queuedTerm);
    }, false);
    request.addEventListener("error", searchDone, false);
    request.send(null);
  }

  function search(term)
  {
    var results = index.search(term);

    // The element where search results should be displayed, adjust as needed.
    var target = document.querySelector(".search-results");

    while (target.firstChild)
      target.removeChild(target.firstChild);

    var title = document.createElement("h1");
    title.id = "search-results";
    title.className = "list-title";

    if (results.length == 0)
      title.textContent = `No results found for “${term}”`;
    else if (results.length == 1)
      title.textContent = `Found one result for “${term}”`;
    else
      title.textContent = `Found ${results.length} results for “${term}”`;
    target.appendChild(title);
    document.title = title.textContent;

    var template = document.getElementById("search-result");
    for (var result of results)
    {
      var doc = lookup[result.ref];

      // Fill out search result template, adjust as needed.
      var element = template.content.cloneNode(true);
      element.querySelector(".summary-title-link").href =
          element.querySelector(".read-more-link").href = doc.uri;
      element.querySelector(".summary-title-link").textContent = doc.title;
      element.querySelector(".summary").textContent = truncate(doc.content, 70);
      target.appendChild(element);
    }
    // title.scrollIntoView(true);

    searchDone();
  }

  // This matches Hugo's own summary logic:
  // https://github.com/gohugoio/hugo/blob/b5f39d23b8/helpers/content.go#L543
  function truncate(text, minWords)
  {
    var match;
    var result = "";
    var wordCount = 0;
    var regexp = /(\S+)(\s*)/g;
    while (match = regexp.exec(text))
    {
      wordCount++;
      if (wordCount <= minWords)
        result += match[0];
      else
      {
        var char1 = match[1][match[1].length - 1];
        var char2 = match[2][0];
        if (/[.?!"]/.test(char1) || char2 == "\n")
        {
          result += match[1];
          break;
        }
        else
          result += match[0];
      }
    }
    return result;
  }
}, false);