TypeScript 5.0 introduces significant improvements. After upgrading to TypeScript 5, here are the key features.

New Features

Decorators

// Experimental decorators
function logged(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    const original = descriptor.value;
    descriptor.value = function(...args: any[]) {
        console.log(`Calling ${propertyKey}`);
        return original.apply(this, args);
    };
}

class MyClass {
    @logged
    myMethod() {
        // Method implementation
    }
}

Const Type Parameters

// Const type parameters
function getValue<T extends readonly string[]>(values: T) {
    return values[0];
}

const result = getValue(['a', 'b', 'c'] as const);
// result is 'a' (not string)

Performance Improvements

  • Faster compilation - Up to 2x faster
  • Smaller package size - Reduced dependencies
  • Better memory usage - Optimized

Migration Guide

Update Dependencies

npm install -D typescript@^5.0.0

Update tsconfig.json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "lib": ["ES2022"],
    "experimentalDecorators": true
  }
}

Best Practices

  1. Upgrade gradually - Test compatibility
  2. Use new features - Leverage improvements
  3. Update config - New options
  4. Test thoroughly - Verify behavior
  5. Monitor performance - Track improvements
  6. Stay updated - New releases
  7. Document changes - Team knowledge
  8. Review code - Type improvements

Conclusion

TypeScript 5.0 provides:

  • New language features
  • Performance improvements
  • Better developer experience
  • Smaller package size

Upgrade gradually, test thoroughly. The features shown here improve TypeScript development.

TypeScript 5.0 from April 2023, covering new features and migration guide.