How to fix 'X' is not exported from 'Y' in TypeScript

// Check the module file (module.ts)
export const myFunction = () => {};      // Named export
export default class MyClass {};         // Default export
export { helperFunction };               // Re-export
export type { MyType };                  // Type export

// Common mistakes:
// const notExported = () => {};         // NOT exported - can't import this
// function privateHelper() {}           // NOT exported - can't import this

# For npm packages, check the package.json exports field
cat node_modules/package-name/package.json | grep -A5 -B5 '"exports"'

# For local files, use TypeScript compiler to list exports
npx tsc --declaration --emitDeclarationOnly --outDir /tmp module.ts
cat /tmp/module.d.ts

// MODULE exports:
// export const myFunction = () => {};
// export default class MyClass {};

// CORRECT imports:
import { myFunction } from './module';      // Named import for named export
import MyClass from './module';             // Default import for default export
import MyClass, { myFunction } from './module'; // Mixed import

// WRONG imports (cause TS2305):
import myFunction from './module';          // Default import for named export
import { MyClass } from './module';         // Named import for default export
import * as everything from './module';     // This works, but then use everything.myFunction

// MODULE (CommonJS style):
// export = { myFunction, MyClass };

// CORRECT import:
import * as module from './module';         // ES module import
// or with esModuleInterop:
import module from './module';

// Also ensure tsconfig.json has:
// {
//   "compilerOptions": {
//     "esModuleInterop": true,
//     "allowSyntheticDefaultImports": true
//   }
// }

// MODULE exports:
export const formatDate = () => {};
export const FormatDate = () => {};  // Different name!
export const FORMATDATE = () => {};  // Another different name!

// WRONG imports:
import { formatdate } from './module';  // lowercase 'd'
import { Formatdate } from './module';  // missing capital 'D'
import { formatDate } from './module';  // ✓ Correct
import { FormatDate } from './module';  // ✓ Correct (different export)
import { FORMATDATE } from './module';  // ✓ Correct (different export)

// Use IDE features to avoid typos:
// 1. Let auto-complete suggest exports
// 2. Ctrl+Click/Cmd+Click on import to jump to definition
// 3. Use "Go to Definition" (F12) to see the actual export

# Check type definitions for a package
cat node_modules/@types/package-name/index.d.ts | head -50

# Or examine the package's main entry point
cat node_modules/package-name/dist/index.js | grep -i "export"

// File: src/components/Button.ts
export const Button = () => {};  // ✓ Exported

// File: src/components/index.ts (barrel file)
export { Button } from './Button';  // ✓ Re-exports Button
// export { Input } from './Input';  // ✗ Missing - Input won't be available

// File: src/index.ts
export * from './components';  // ✓ Exports everything from components

// CORRECT import:
import { Button } from './src';  // Works through re-export chain

// Debug broken chains:
// 1. Check each file in the chain exports the item
// 2. Verify no typos in re-export statements
// 3. Ensure circular dependencies aren't breaking exports

// Re-export with rename
export { Button as MyButton } from './Button';

// Re-export type only
export type { Props } from './Button';

// Aggregate exports
export * from './components';
export * from './utils';

// Conditional exports (package.json)
// {
//   "exports": {
//     ".": {
//       "import": "./dist/esm/index.js",
//       "require": "./dist/cjs/index.js"
//     },
//     "./components": "./dist/esm/components/index.js"
//   }
// }

# Check what changed in a package
npm view package-name versions  # List all versions
npm view package-name@latest    # Latest version info

# Compare your version with latest
npm list package-name           # Your installed version
npm info package-name version   # Latest available

# Check changelog for breaking changes
# Common breaking changes:
# - Renamed exports
# - Removed exports
# - Changed from default to named exports (or vice versa)
# - Added new required peer dependencies

# Update package (if appropriate)
npm install package-name@latest

# Or check migration guide
# Most packages have migration guides for major versions

// If export was removed but still exists at runtime
declare module "old-package" {
  export const removedExport: any;
}

// Or use require for CommonJS modules
const { removedExport } = require("old-package");

// tsconfig.json
{
  "compilerOptions": {
    "moduleResolution": "node",
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "resolveJsonModule": true,

    // For modern packages
    "module": "esnext",

    // For type-only imports
    "importsNotUsedAsValues": "preserve",

    // Path mapping
    "baseUrl": ".",
    "paths": {
      "@/*": ["src/*"]
    }
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules"]
}

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

# Or from command line:
npx tsc --build --clean