How to fix ts-node does not support 'emitDecoratorMetadata' without 'experimentalDecorators' in TypeScript

{
  "compilerOptions": {
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    // Other compiler options...
    "target": "ES2022",
    "module": "commonjs",
    "strict": true
  }
}

# For NestJS projects
cat tsconfig.json | grep -A2 -B2 "experimentalDecorators"
cat tsconfig.json | grep -A2 -B2 "emitDecoratorMetadata"

# Run with --show-config to see what ts-node is using
npx ts-node --show-config

# Or specify the tsconfig explicitly
npx ts-node -P tsconfig.json your-file.ts

# For projects with multiple configs (like tsconfig.build.json)
npx ts-node -P tsconfig.build.json your-file.ts

// tsconfig.json (development)
{
  "extends": "./tsconfig.base.json",
  "compilerOptions": {
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true
  }
}

// tsconfig.build.json (production)
{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true
  }
}

// package.json - WRONG example
{
  "scripts": {
    "start": "ts-node --compiler-options '{"emitDecoratorMetadata":true}' src/main.ts"
  }
}

// Option 1: Specify both options
{
  "scripts": {
    "start": "ts-node --compiler-options '{"experimentalDecorators":true,"emitDecoratorMetadata":true}' src/main.ts"
  }
}

// Option 2: Use tsconfig.json (recommended)
{
  "scripts": {
    "start": "ts-node -P tsconfig.json src/main.ts"
  }
}

# Check nest-cli.json configuration
cat nest-cli.json

# Ensure it references the correct tsconfig
{
  "collection": "@nestjs/schematics",
  "sourceRoot": "src",
  "compilerOptions": {
    "tsConfigPath": "tsconfig.json"
  }
}

# Check current versions
npx ts-node --version
npx tsc --version

# Update packages
npm install --save-dev typescript@latest ts-node@latest

# Or update with specific versions
npm install --save-dev [email protected] [email protected]

npm cache clean --force
rm -rf node_modules package-lock.json
npm install

// register.ts or main.ts
import { register } from 'ts-node';

register({
  compilerOptions: {
    experimentalDecorators: true,
    emitDecoratorMetadata: true,
    target: 'ES2022',
    module: 'commonjs'
  }
});

// Now import your application
import { AppModule } from './app.module';
// ... rest of your code

// In your main JavaScript file
require('ts-node').register({
  compilerOptions: {
    experimentalDecorators: true,
    emitDecoratorMetadata: true
  }
});

require('./src/main.ts');

// jest.config.js
module.exports = {
  preset: 'ts-jest',
  globals: {
    'ts-jest': {
      tsconfig: {
        experimentalDecorators: true,
        emitDecoratorMetadata: true
      }
    }
  }
};

# Compile TypeScript to JavaScript
npx tsc

# Run the compiled JavaScript
node dist/main.js

{
  "scripts": {
    "build": "tsc",
    "start": "node dist/main.js",
    "dev": "concurrently "tsc --watch" "nodemon dist/main.js""
  }
}

npm install --save-dev concurrently nodemon

npm install --save-dev ts-node-dev

{
  "scripts": {
    "dev": "ts-node-dev --respawn --transpile-only src/main.ts"
  }
}