These functions utilize Cloudflare Functions to dynamically inject meta tags server-side for richer link sharing capabilities.

Search engines and social media platforms' crawlers read the initial HTML of a page to index and understand its content. These crawlers often do not execute JavaScript, meaning dynamically added client-side content, including metatags, may not be indexed or recognized. This is why we render our metatags on server-side.

However, these server-side injected metatags do not automatically update during client-side navigation managed by react-router. To address this, we implement additional client-side logic - see src/pages/metatags.ts. This client-side metatag management is particularly important for compatibility with features like Safari's native share, which relies on metatags like og:url to represent the shared page.

Currently, there are 2 types of cloudflare functions developed

• Meta Data Injectors - Workers that inject Open Graph standardized meta tags into the header of specific webpages.
  • Currently we support this functionality for three separate webpages: NFT Assets, NFT Collections, and Token Detail Pages
  • These functions query data from GraphQL and then formats them into HTML meta tags to be injected
• Dynamically Generated Images - Utilizes Vercel's Open Graph Image Generation Library to create custom thumbnails for specific webpages
  • Currently supports NFT Assets, NFT Collections, and Token Detail Pages
  • These functions query data from GraphQL, and utilize Satori to convert HTML into a png image response which is then returned when the api is called.
  • Can be found in the api/image folder.

Testing is done utilizing a custom jest environment as well as Cloudflare's local tester: wrangler. Wrangler enables testing locally by running a proxy ("Miniflare") to wrap localhost. Tests run against a proxy server, so you'll need to start it before running tests:

• Manually run yarn start:cloud to setup wrangler on localhost:3000 and proxy on localhost:3001
• Run unit tests with yarn test:cloud

Functions will be deployed to Cloudflare where they will be ran automatically when the appropriate route is hit.

• Caching: In order to speed up webpage requests, repeated GraphQL queries will be saved and pulled using Cloudflare's Cache API.

• yarn start:cloud (NODE_OPTIONS=--dns-result-order=ipv4first PORT=3001 npx wrangler pages dev --node-compat --proxy=3001 --port=3000 -- yarn start), script to start local wrangler environment

  • npx wrangler pages dev: this basis of this command which starts a local instance of wrangler to test cloud functions
  • --node-compat: wrangler option that enables compatibility with Node.js modules
  • --proxy:3001: telling the proxy to listen on port 3001
  • --port=3000: telling wrangler to run our proxy on port 3000
  • NODE_OPTIONS=--dns-result-order=ipv4first: wrangler still serves to IPv4 which isn't compatible with Node 18 which default resolves to IPv6 so we need to specify to serve to IPv4
  • PORT-3001 --yarn start: runs default yarn start on port 3001
    • when exiting Miniflare, may need to clean up process on port 3001 separately: kill $(lsof -t -i:3001)

• yarn test:cloud (NODE_OPTIONS=--experimental-vm-modules yarn jest functions --watch --config=functions/jest.config.json), script to test cloud functions with jest

  • NODE_OPTIONS=--experimental-vm-modules: support for ES Modules and Web Assembly
  • --config=functions/jest.config.json: specifying which config file to use

  Additional Documents

  • Open Graph Protocol
  • Open Graph Image Generation
  • Cloudflare Workers
  • HTML Rewriter
  • Cache API