Custom Elements Manifest Validator

About

Custom Elements Manifest Validator validates an npm package and its custom elements manifest against the Custom Elements Manifest specification and checks for common mistakes and best practices.

Passing validation means that the package is more likely to work well in tools that consume custom elements manifests such as component catalogs, IDEs, and type checkers.

Checks

The validator performs several checks, including:

package.json checks

• type is set to "module"
• description is set
• main is set, and the file exists
• customElements is set, and the file exists
• exports is set
• keywords includes "web components"

Custom Elements Manifest checks

• schemaVersion is set and current (2.1.0)
• The manifest file validates against the Custom Elements Manifest schema
• deprecated is unset or false
• readme is unset or set to a valid path
• TODO: The manifest file is exported in package.json
• References
  • All package-local references resolve correctly to an export or declaration (TODO: support cross-package references)
  • All package-local type references resolve to a declaration file (TODO: support package exports and cross-package references)
  • All package-local type references have valid start and end offsets.
  • TODO: Type references are exported from their declaration file.
  • TODO: Source references point to valid files and have valid start and end offsets.
• Modules
  • Module file exists
  • Exports
    • TODO: export names are valid
    • TODO: If export name is * the export module is defined
    • TODO: exported declarations have descriptions
    • TODO: exported declarations have types
  • Declarations
    • Custom Elements
    • Custom element declarations with a tagName are exported as a custom-element-export at least once.
    • TODO: custom element names are valid
    • TODO: custom element descriptions are set
    • TODO: CSS property names are valid
    • TODO: part names are valid
    • TODO: slot names are valid
    • TODO: Event types extend Event
    • TODO: Attribute fieldName references valid field
    • TODO: inheritedFrom resolves