How to fix Re-exports require an export specifier in TypeScript

// WRONG - missing export specifier
export * from './utils';

// CORRECT - export everything as a namespace
export * as utils from './utils';

// CORRECT - export specific named exports
export { functionA, functionB } from './utils';

// CORRECT - export default
export { default } from './utils';

// CORRECT - export everything (valid in some contexts)
export * from './utils/*';  // Note: this exports from multiple files

npx tsc
# or
npm run build

// WRONG barrel file
export * from './button';
export * from './input';
export * from './form';

// CORRECT barrel file - export specific items
export { Button, ButtonProps } from './button';
export { Input, InputProps } from './input';
export { Form, FormProps } from './form';

// CORRECT barrel file - namespace exports
export * as Button from './button';
export * as Input from './input';
export * as Form from './form';

// CORRECT barrel file - mixed approach
export { Button, ButtonProps } from './button';
export * as Input from './input';
export { default as Form } from './form';

// src/components/index.ts
export { Button, type ButtonProps } from './Button';
export { Input, type InputProps } from './Input';
export { Card, type CardProps } from './Card';
export { default as Modal } from './Modal';

// CommonJS style (WRONG in ES modules)
module.exports = require('./utils');

// ES module equivalent (CORRECT)
export * from './utils';  // Still needs fixing!
export * as utils from './utils';  // Better

// CommonJS re-export pattern
exports.foo = require('./foo').foo;
exports.bar = require('./bar').bar;

// ES module equivalent
export { foo } from './foo';
export { bar } from './bar';

// For default exports
const utils = require('./utils');
module.exports = utils;

// ES module equivalent
export { default } from './utils';
// or
import utils from './utils';
export default utils;

{
  "type": "module"
}

{
  "compilerOptions": {
    "module": "ESNext",
    "moduleResolution": "node16"
  }
}

{
  "compilerOptions": {
    "module": "ESNext",
    "moduleResolution": "node16",
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "isolatedModules": true,
    "resolveJsonModule": true,

    // For namespace exports
    "preserveSymlinks": true,

    // For better re-export support
    "verbatimModuleSyntax": true
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules"]
}

# In VS Code: Ctrl/Cmd + Shift + P, then "TypeScript: Restart TS Server"

// WRONG - exports both value and type
export { User, type UserProps } from './types';

// BETTER - separates type and value exports
export { User } from './types';
export type { UserProps } from './types';

// CORRECT - type-only re-export
export type { UserProps } from './types';

// For multiple type exports
export type { UserProps, PostProps, CommentProps } from './types';

// Namespace for types
export type * as Types from './types';

// Regular import (includes runtime code)
import { User } from './types';

// Type-only import (removed during compilation)
import type { UserProps } from './types';

# Check current TypeScript version
npx tsc --version

# Update TypeScript
npm install typescript@latest --save-dev

# Or update to a specific version
npm install typescript@5.0.0 --save-dev

{
  "devDependencies": {
    "typescript": "^5.0.0"
  },
  "engines": {
    "node": ">=16.0.0"
  }
}

# Remove compiled files
rm -rf dist build

# Clear TypeScript cache
rm -rf node_modules/.cache

# Reinstall if needed
npm install

# Compile fresh
npx tsc --build --clean
npx tsc