scripts/js-api

TypeScript build pipeline for React Native's JavaScript API.

Overview

yarn build-types is a custom build pipeline for translating React Native's Flow source code to TypeScript.

Specifically, it reduces the runtime JavaScript API of react-native into two outputs:

• Generated TypeScript types
  Public user types for react-native, shipped to npm
  packages/react-native/types_generated/
• ‌Public API snapshot
  Snapshot file of the public API shape, used by maintainers
  packages/react-native/ReactNativeApi.d.ts

Dependencies

yarn build-types makes use of the following dependencies, composed with other pre/post transformation steps and dependency resolution.

• Flow → TypeScript conversion: flow-api-extractor
• TypeScript → (initial) API rollup: @microsoft/api-extractor

Usage

Build generated types + API snapshot

Maintainers should run this script whenever making intentional API changes.

# Build types + API snapshot
yarn build-types [--validate]

# Build types without API snapshot
yarn build-types --skip-snapshot

Diff API snapshot compatibility

This script is run by CI to compare changes to ReactNativeApi.d.ts between commits.

# Compare two versions of the API snapshot
yarn js-api-diff <before.d.ts> <after.d.ts>

{
  "result": "BREAKING",
  "changedApis": [
    "ViewStyle"
  ]
}

Configuration

Sparse configuration options are defined and documented in scripts/js-api/config.js.

About the two output formats

Generated TypeScript types

types_generated/

Directory providing TypeScript user types for the react-native package, distributed via npm.

• Gitignored.
• Scoped to the index.d.ts entry point via package.json#exports.
• Preserves unstable_ and experimental_ APIs.
• Preserves doc comments.
• Preserves source file names (for go to definition).

Public API snapshot

ReactNative.d.ts

Provides a human-readable, maintainable reference of the React Native's public JavaScript API, optimized for developers and diff tooling.

• Committed to the repo.
• Strips unstable_ and experimental_ APIs.
• Strips doc comments.
• Strips source file names (types are merged into a single program).
• Versions exported APIs with an 8 char SHA hash, which will be updated when any input type dependencies change shape.