Using Vectorize to build an unreasonably good search engine in 160 lines of code

Originally published: November 11, 2024
Last updated: December 08, 2024

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Prerequisites

• A Jekyll site deployed on Netlify.

• Basic knowledge of JavaScript and Jekyll’s structure.

• PartyKit and Cloudflare account access.

Step 1: Install Dependencies

You’ll need the following packages:

• PartyKit: For deploying the search backend.

• Vectorize: For creating and managing vector embeddings.

1. Install PartyKit CLI:

npm install -g @partykit/cli

1. Set up a Vectorize project in Cloudflare following their documentation. This will allow you to create the embeddings for search.

Step 2: Extract Content from Jekyll Site

1. Create a new JavaScript file (extract-content.js) in your Jekyll project root directory. This script will extract text content from your markdown files (_posts folder) to use for search.

2. In extract-content.js, write a script to read through your Jekyll markdown files and extract the main content:

const fs = require('fs');

const path = require('path');

  

const postsDir = path.join(__dirname, '_posts');

const posts = fs.readdirSync(postsDir).map(filename => {

  const filePath = path.join(postsDir, filename);

  const content = fs.readFileSync(filePath, 'utf-8');

  const title = content.match(/title:\s*(.*)/)[1];

  const body = content.split('---')[2].trim();

  return { title, body };

});

  

fs.writeFileSync('content.json', JSON.stringify(posts, null, 2));

This script will create a content.json file with titles and content from each post.

Step 3: Create Embeddings with Vectorize

1. Use the content in content.json to generate vector embeddings. You’ll send each post’s content to Vectorize to create an embedding that represents the semantic meaning of the text.

2. Write a script (generate-embeddings.js) that reads from content.json and sends each post’s content to Vectorize:

const fetch = require('node-fetch');

const fs = require('fs');

  

const posts = require('./content.json');

const VECTORIZE_API = 'https://vectorize.cloudflare.com/v1/embeddings';

  

async function getEmbeddings(text) {

  const response = await fetch(VECTORIZE_API, {

    method: 'POST',

    headers: { 'Content-Type': 'application/json' },

    body: JSON.stringify({ input: text })

  });

  const data = await response.json();

  return data.embedding;

}

  

async function main() {

  for (const post of posts) {

    post.embedding = await getEmbeddings(post.body);

  }

  fs.writeFileSync('embeddings.json', JSON.stringify(posts, null, 2));

}

  

main();

This creates embeddings.json with content and vector embeddings.

Step 4: Set Up PartyKit Backend

1. Create a new PartyKit project:

partykit create search_backend

cd search_backend

1. Define a PartyKit server in index.js that will handle search queries:

import { search } from './search.js';

  

export default function (app) {

  app.get('/search', async (req, res) => {

    const query = req.query.q;

    const results = await search(query);

    res.json(results);

  });

}

1. In search.js, write a function to compare the query vector with post embeddings and return the best matches:

import { cosineSimilarity } from './cosine-similarity';

  

const posts = require('./embeddings.json');

  

export async function search(query) {

  const queryEmbedding = await getEmbeddings(query);

  return posts

    .map(post => ({

      ...post,

      similarity: cosineSimilarity(queryEmbedding, post.embedding)

    }))

    .sort((a, b) => b.similarity - a.similarity)

    .slice(0, 5);

}

Step 5: Deploy PartyKit Backend

1. Run the PartyKit CLI to deploy:

partykit deploy

1. You’ll receive a public URL to access your PartyKit backend, e.g., https://your-backend.partykit.dev.

Step 6: Integrate Search Frontend in Jekyll

1. Create a search page in your Jekyll site (e.g., search.html) with an input box and button for searching.

2. Add JavaScript in search.html to handle user input and call the PartyKit backend:

<input type="text" id="searchBox" placeholder="Search...">

<button onclick="performSearch()">Search</button>

<div id="results"></div>

  


<script>

  async function performSearch() {

    const query = document.getElementById('searchBox').value;

    const response = await fetch('https://your-backend.partykit.dev/search?q=' + encodeURIComponent(query));

    const results = await response.json();

    document.getElementById('results').innerHTML = results.map(post => `

      <h3>${post.title}</h3>

      <p>${post.body.slice(0, 100)}...</p>

    `).join('');

  }

</script>

Step 7: Deploy the Updated Jekyll Site on Netlify

1. Commit and push your Jekyll changes to your Git repository. Netlify will automatically rebuild your site.

2. Visit your search page on Netlify and test out the functionality.

Summary

You now have a Jekyll site with a vector-based search feature hosted on Netlify using PartyKit and Cloudflare’s Vectorize! This approach enables semantic search for more accurate and relevant results.

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