Block Protocol template: HTML

Step one: copy this template

See https://blockprotocol.org/docs/blocks/develop

TL;DR: Run npx create-block-app@latest [your-block-name] --template=html

Other templates are available. See npx create-block-app@latest --help

Step two: decide on and build the entity type for your block

A key part of the Block Protocol is the use of types to describe the data your block will work with.

Your block should be associated with an “entity type” which will be used by embedding applications to understand what sorts of entities can be sent to it (e.g. what properties do they have?).

You can create an entity type on blockprotocol.org — see the docs for a full guide.

Once you have created the type representing the data your block needs, copy its URL for use in the next step.

Step three: update your block's metadata

1. Change into the folder: cd path/to/your-block-name

2. Update the contents of block-metadata.json:

• set schema to the URL of the entity type you created in the previous step
• optionally update additional fields which will be used to identify and describe the block when published:
  • displayName: a friendly display name
  • examples: an array of example data structures your block would accept and use
  • image: a preview image showing your block in action (in place of public/block-preview.png)
  • icon: an icon to be associated with your block (in place of public/omega.svg)
  • name: a slugified name for your block (which may differ to the package name in package.json)
    • this may either be in the format slug or @namespace/slug where namespace is your blockprotocol.org username

Step four: implement your block's logic and UI

1. Write your block starting in app.html. To test it during development:

   • edit dev/index.html to give your block starting properties

   • run the dev server with yarn dev (or npm run dev)

2. When finished, run yarn build (or npm run build), which:

   • Bundles the component into a single source file
   • Once uploaded to a remote folder, embedding applications can access block-metadata.json. This file is documented in full here.

Please see the Block Protocol docs for a fuller explanation of querying, creating and updating entity data from your block. You can format your code using yarn format (or npm run format).

Step three: publish your block

Head over to blockprotocol.org to read instructions on publishing your block.

External Dependencies

This template assumes there is no bundling process. You will need to reference external dependencies using ES Modules. Tools like esm.sh or unpkg.com can make this much easier.

Debugging

The component can be debugged locally by first starting yarn dev.

Now (using VS Code), go to the Debug tab, select "Launch Chrome" and start the debugger (F5).

You should now be able to set breakpoints and step through the code.