@litsx/prop-types

Compatibility support for lowering React prop-types into LitSX.

This package has two surfaces:

• @litsx/prop-types/runtime for the runtime helper layer used by React compat transforms
• @litsx/prop-types for descriptor builders that return Lit property option objects

For native LitSX authoring, prefer TypeScript prop inference and ^properties(...) directly.

Runtime Helpers

Import runtime helpers from @litsx/prop-types/runtime when you need the same validation/options layer that the React compat transform emits:

import {
  required,
  oneOf,
  oneOfType,
  arrayOf,
  objectOf,
  shape,
  exact,
  instanceOf,
} from "@litsx/prop-types/runtime";

^properties({
  title: {
    type: String,
    ...required(),
  },
  status: {
    type: String,
    ...oneOf(["idle", "busy"]),
  },
  meta: {
    type: Object,
    attribute: false,
    ...shape({
      count: Number,
      active: Boolean,
    }),
  },
});

These helpers return partial Lit property options:

• converter
• hasChanged
• attribute: false where structured values should not round-trip through attributes

Validation is strict and throws on invalid values.

Descriptor Builders

The package root exports descriptor builders that produce Lit property option objects:

import PropTypes from "@litsx/prop-types";

class FancyCounter extends LitElement {
  static properties = {
    label: PropTypes.string.attribute("aria-label").reflect(),
    count: PropTypes.number.withConverter(PropTypes.number, {
      converter: {
        fromAttribute: (value) => Number(value ?? 0),
        toAttribute: (value) => String(value ?? 0),
      },
    }),
  };
}

That surface is available when you want descriptor composition in plain JavaScript, but it is not the recommended primary style for native LitSX authoring.

Recommended Native LitSX Authoring

Prefer:

• TypeScript prop inference
• ^properties(...)

Use @litsx/babel-preset-react-compat when you want React propTypes migration support; that preset lowers propTypes through @litsx/babel-plugin-litsx-proptypes and these runtime helpers.