blog-typescript-features-you-should-no-longer-use-03.js

export class Person {
  names = [];
  
  @Confirmable('Are you sure?')
  @Confirmable('Are you super, super sure? There is no going back!')
  addName(name) {
    this.names.push(name);
  }
}

// Method Decorator
function Confirmable(message: string) {
  return function (target: Object, key: string | symbol, descriptor: PropertyDescriptor) {
    const original = descriptor.value;
    
    descriptor.value = function( ... args: any[]) {
      const allow = confirm(message);
      if (allow) {
        const result = original.apply(this, args);
        return result;
      } else {
        return null;
      }
    };
    
    return descriptor;
  };
}