This is the TypeScript/JavaScript implementation of the PureHTML specification.
You need to install NodeJS first, then follow the steps explained in the documentation.
See https://purescraps.github.io/purehtml/ for documentation and playground.
You may use yaml-language-server for autocompletions.
Add this line to top of your yaml:
# yaml-language-server: $schema=typescript/src/config-schema.json