Proxy validation and sanitization

ProxyValidator.js

const validator = {
  set(obj, prop, value, receiver) {
    if (prop === "age") {
      if (!Number.isInteger(value)) {
        throw new TypeError("The age is not an integer");
      }
      if (value > 200) {
        throw new RangeError("The age seems invalid");
      }
    }

    // The default behavior to store the value
    return Reflect.set(obj, prop, value, receiver);
  },
};

const person = new Proxy({}, validator);

person.age = 100;
console.log(person.age); // 100
// person.age = "young"; // Throws an exception
// person.age = 300; // Throws an exception