Formats
First, indicate the directory to resolve format modules from:
roots.register.formats('./')
Then, create *.format.{js,ts} modules.
Each should export the required properties of the WordPress Editor Format API. They should also export the format name (sometimes referred to as namespace in WordPress documentation).
Example​
Using named exports:
export const name = `bud-project/example-format`
export const title = `Example format`
export const tagName = 'span'
export const className = 'example-format'
Using a default export:
export default {
  name: `bud-project/example-format`,
  title: `Example format`,
  tagName: 'span',
  className: 'example-format',
}