babel/babel

The inspected user surfaces cover programmatic compilation, command-line output, runtime loading, browser execution, and linting integration. Compiler configuration controls plugins, presets, file selection, environments, and emitted formatting. Target-aware preset selection and source maps support application build pipelines. This catalog describes inspected feature families and does not claim exhaustive coverage of every transform package.

• Core exposes callback, synchronous, and Promise-based transformations; in Babel 8, transform without a callback throws and directs callers to transformSync.
  packages/babel-core/src/transform.ts#L31-64packages/babel-core/src/index.ts#L78-95
• CLI accepts plugins, presets, config-file, env-name, root-mode, ignore/only filters, source-map modes, and compact/minified/comment formatting controls.
  packages/babel-cli/src/babel/options.ts#L16-52packages/babel-cli/src/babel/options.ts#L61-105
• CLI supports stdin, concatenated out-file output, directory output, extension replacement or preservation, dotfile inclusion, asset copying, and watch mode.
  packages/babel-cli/src/babel/options.ts#L108-162packages/babel-cli/src/babel/file.ts#L243-247packages/babel-cli/src/babel/dir.ts#L95-107
• BABEL_SHOW_CONFIG_FOR selects a regular file and prints its applicable root, relative, and programmatic configurations in ascending priority.
  packages/babel-core/src/config/files/configuration.ts#L351-365packages/babel-core/src/config/config-chain.ts#L265-273
• preset-env filters transforms using compatibility data, targets, include/exclude options, and caller module capabilities; useBuiltIns adds a core-js 3 polyfill plugin.
  packages/babel-preset-env/src/index.ts#L252-283packages/babel-preset-env/src/index.ts#L290-313
• Standalone bundles env, React, TypeScript, Flow, and historical presets; it exposes transform APIs and automatically processes supported script tags on DOMContentLoaded.
  packages/babel-standalone/src/index.ts#L59-86packages/babel-standalone/src/index.ts#L177-198packages/babel-standalone/src/index.ts#L259-283
• @babel/register installs reversible compilation hooks and source-map support; babel-node installs register and offers transformed eval/print execution, with REPL imports and exports explicitly rejected.
  packages/babel-register/src/hook.ts#L43-63packages/babel-node/src/_babel-node.ts#L48-67packages/babel-node/src/_babel-node.ts#L97-141
• @babel/eslint-parser provides parse and parseForESLint; the latter returns the parsed AST, analyzed scopeManager, and Babel-derived visitorKeys.
  eslint/babel-eslint-parser/src/index.ts#L13-35