const person = {};
Object.defineProperty(person, 'name',
    {
        value: 'Alice',
        writable: false,
        enumerable: true,
        configurable: false
    }
);

const animal = {};
Object.defineProperties(animal, {
    name: {
        value: 'Dog',
        writable: true
    },
    sound: {
        value: 'Woof',
        enumerable: false
    }
});

const myObj = { age: 30 };
const descriptor =
      Object.getOwnPropertyDescriptor(myObj, 'age');

console.log(descriptor);
/* Output: 
  {
    value: 30, 
    writable: true,
    enumerable: true,
    configurable: true
  }
*/

const button = 
      document.createElement('button');

Object.definedProperty(button, 'clicked', {
  value: false,
  writable: true,
  enumerable: false,
  configurable: false
})

button.addEventListener('click', () => {
  button.clicked = true
});

const propSymbol = Symbol("propName");
const propSymbol2 = Symbol("propName");

propSymbol === propSymbol2 // false

const propSymbol = new Symbol("propName");

const nameSymbol = Symbol("name");
const surnameSymbol = Symbol("surname");

const person = {
  name: 'John',
  surname: 'Doe',
  [nameSymbol]: "Jane",
  [surnameSymbol]: "Blue"
}

// my-module-1.js
export const propSymbolShare = Symbol.for("propName");

// my-module-2.js
export const propSymbolShare = Symbol.for("propName");

// index.js
import { propSymbolShare as propSymbolShareM1 } from './my-module.js'
import { propSymbolShare as propSymbolShareM2 } from './my-module-2.js'

console.log(propSymbolShareM1 === propSymbolShareM2); // true

function Range(start, end) {
  this.start = start;
  this.end = end;

  this[Symbol.iterator] = function*() {
    let current = this.start;
    const last = this.end;

    while (current <= last) {
      yield current++;
    }
  }

  return this;
}

for (let num of new Range(1, 10)) {
  console.log(num);
}

const ClickedSymbol = Symbol('clicked')

const button = 
      document.createElement('button');

button[ClickedSymbol] = false

button.addEventListener('click', () => {
  button[ClickedSymbol] = true
});

const weakmap = new WeakMap();
const key = { name: "John Doe" };
weakmap.set(key, "Some value");

const value = weakmap.get(key); // "Some value"

weakmap.delete(key); // true
weakmap.has(key); // false

const ClickedWeakMap = new WeakMap()

const button = 
      document.createElement('button');

ClickedWeakMap.set(button, false)

button.addEventListener('click', () => {
  ClickedWeakMap.set(button, true)
});

const weakSet = new WeakSet();

const obj1 = {};

weakSet.add(obj1);

console.log(weakSet.has(obj1)); // true
weakSet.delete(obj1);
console.log(weakSet.has(obj1)); // false

const ClickedWeakSet = new WeakSet()

const button = 
      document.createElement('button');

button.addEventListener('click', () => {
  ClickedWeakSet.add(button)
});

const target = { age: 31 };
const handler = {
  get(_target, prop) {
    if (prop === "birthYear") {
       return new Date().getFullYear() - _target['age'];
    }
    return _target[prop];
  }
};

const proxy = new Proxy(target, handler);
console.log(proxy.birthYear); // 1992

const target = { age: 25 };
const handler = {
  set(_target, prop, value) {
    if (prop === "age" 
        && (typeof value !== "number" || value < 0 || value > 150))
      throw new TypeError("Invalid age value");

    _target[prop] = value;
    return true;
  },
};

const proxy = new Proxy(target, handler);
proxy.age = 30; // Works fine
proxy.age = "thirty"; // Throws TypeError: "Invalid age value"

const handlers = {
  set(t, p, v) {
    if (p === 'clicked')
      throw new Error('You cannot change this')
    t[p] = v
  }
}
const button = document.createElement('button')
button.addEventListener('click', () => {
  button.clicked = true
});

const wrappedButton = new Proxy(button, handlers)

const numbers = [1, 2, 3];
const sum = (a, b, c) => a + b + c;

// Using Reflect.apply()
const result = Reflect.apply(sum, null, numbers);

console.log(result); // Output: 6

const obj = { x: 42, y: 'hello' };

// Using Reflect.get()
const value = Reflect.get(obj, 'x');

console.log(value); // Output: 42

const obj = { x: 42 };
const newObj = Object.create(obj);

// Using Reflect.set()
Reflect.set(newObj, 'x', 13);

console.log(newObj.x); // Output: 13

const obj = {};

// Using Reflect.defineProperty()
Reflect.defineProperty(obj, 'x', {
  value: 42,
  writable: false
});

console.log(obj.x); // Output: 42

const obj = { x: 42, [Symbol('key')]: 'symbolValue' };

// Using Reflect.ownKeys()
const keys = Reflect.ownKeys(obj);

console.log(keys); // Output: ['x', Symbol(key)]