npm install hugo-algolia

hugo-algolia --config ./config.toml

//$node_modules_prefix/lib/node_modules/hugo-algolia/lib/index.js

HugoAlgolia.prototype.setCredentials = function() {
/*
   Original code, one can find that it called the module "matter" to handle the
   YAML file. Now YAML can handle the TOML too with the same usage, but the
   author of hugo-algolia has not correct it yet.

   const configMeta = matter.read(self.pathToCredentials);
   const creds = configMeta.data.algolia;

   if (creds) {
     self.algoliaCredentials = {
       indexName: creds.index,
       key: write_key && write_key !== undefined ? write_key : creds.key,
       appID: creds.appID
     };
     self.localIndexName = creds.index;
   }
*/
/*
   Here we directly write the "index", "key", and "appID" here so that them can
   be send to Algolia correctly.

*/
   self.algoliaCredentials = {
       indexName: "Your Index Name",
       key: "Administrator's Key",
       appID: "The Application ID"
     };
     self.localIndexName = "Your Index Name";
 };

hugo-algolia -s --config ./config.toml

<!--$themepath/layouts/partials/head.html-->
<!--Bootstrap-->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>

<!--$themepath/layouts/partials/search.html-->

<div class="aa-input-container" id="aa-input-container">
    <input type="search" id="aa-search-input" class="aa-input-search" placeholder="Search for titles or URIs..." name="search" autocomplete="off" />
    <svg class="aa-input-icon" viewBox="654 -372 1664 1664">
        <path d="M1806,332c0-123.3-43.8-228.8-131.5-316.5C1586.8-72.2,1481.3-116,1358-116s-228.8,43.8-316.5,131.5  C953.8,103.2,910,208.7,910,332s43.8,228.8,131.5,316.5C1129.2,736.2,1234.7,780,1358,780s228.8-43.8,316.5-131.5  C1762.2,560.8,1806,455.3,1806,332z M2318,1164c0,34.7-12.7,64.7-38,90s-55.3,38-90,38c-36,0-66-12.7-90-38l-343-342  c-119.3,82.7-252.3,124-399,124c-95.3,0-186.5-18.5-273.5-55.5s-162-87-225-150s-113-138-150-225S654,427.3,654,332  s18.5-186.5,55.5-273.5s87-162,150-225s138-113,225-150S1262.7-372,1358-372s186.5,18.5,273.5,55.5s162,87,225,150s113,138,150,225  S2062,236.7,2062,332c0,146.7-41.3,279.7-124,399l343,343C2305.7,1098.7,2318,1128.7,2318,1164z" />
    </svg>

</div>
<script src="{{ "https://res.cloudinary.com/jimmysong/raw/upload/rootsongjc-hugo/algoliasearch.min.js" | absURL }}"></script>
<script src="{{ "https://res.cloudinary.com/jimmysong/raw/upload/rootsongjc-hugo/autocomplete.min.js" | absURL }}"></script>
<script>
/*here you need to write your appID and apiKey(not administrator key!)*/
var client = algoliasearch("Application ID", "API Key");
var index = client.initIndex('Your Index Name');
autocomplete('#aa-search-input',
{ hint: false}, {
    source: autocomplete.sources.hits(index, {hitsPerPage: 8}),
    displayKey: 'name',
    templates: {
        suggestion: function(suggestion) {
            console.log(suggestion);
            /*here the link format might be need to correct according to your site */
            return '<span>' + '<a href="/' + suggestion.uri.toLowerCase() + '/">' +
            suggestion._highlightResult.title.value + '</a></span>';
        }
    }
});
</script>