method-decorator.ts

const methodToKeyMap = {
  withdrawFromAccountA: "accountA",
  withdrawFromAccountB: "accountB",
};

const minimumAmount = (amount: number) => {
  return (
    target: Object,
    propertyKey: string,
    descriptor: PropertyDescriptor
  ) => {
    const originalFn = descriptor.value;

    descriptor.value = function (...args: any) {
      if (this[methodToKeyMap[propertyKey]] - args[0] > amount) {
        originalFn.call(this, args);
      } else {
        console.log(`${methodToKeyMap[propertyKey]}: Not enough money`);
      }
    };
    return descriptor;
  };
};

class BankMethodDecorator {
  accountA: number = 200;
  accountB: number = 1000;

  @minimumAmount(100)
  withdrawFromAccountA(amount: number) {
    this.accountA = this.accountA - amount;
  }

  @minimumAmount(200)
  withdrawFromAccountB(amount: number) {
    this.accountB = this.accountB - amount;
  }
}

const bankMethodDecorator = new BankMethodDecorator();
bankMethodDecorator.withdrawFromAccountA(200);
bankMethodDecorator.withdrawFromAccountB(200);
console.log(bankMethodDecorator.accountA);
console.log(bankMethodDecorator.accountB);