JS Design Patterns: Proxy, see more at: https://medium.com/p/b8f962affe02

DESIGN_PATTERNS_accessControlWithProxyES6.js

class Products {
  constructor() {
    this.data = [];
  }

  add(product) {
    this.data.push(product);
    return true;
  }

  remove(product) {
    this.data = this.data.filter(currentProduct => product !== currentProduct);

    return true;
  }

  reports() {
    return `Products reports`;
  }
}

class ProductsProxyHandler {
  constructor(User) {
    if (typeof User !== "object") {
      throw new Error("User object is required to initialize products class");
      return false;
    }

    this.user = User;
  }

  get(target, propKey, receiver) {
    const ProductsProxyScope = this;

    const targetValue = Reflect.get(target, propKey, receiver);

    if (typeof targetValue === "function") {
      return function(...args) {
        return ProductsProxyScope.checkPermissions(
          propKey,
          targetValue.bind(this, args),
        );
      };
    } else {
      return targetValue;
    }
  }

  checkPermissions(methodName, func) {
    const userHasPermission = this.user.permissions.some(
      permission => permission === methodName,
    );

    return userHasPermission ? func() : "Not allowed";
  }
}

class ProductsFacade {
  constructor(User) {
    return new Proxy(new Products(), new ProductsProxyHandler(User));
  }
}

class User {
  constructor(name, permissions) {
    this.name = name;
    this.permissions = permissions;
  }
}

const run = () => {
  const userRicardo = new User("Ricardo", ["add"]);

  const ProductInstance = new ProductsFacade(userRicardo);

  console.log(ProductInstance.remove("something"));
};

run();