function a() {
   console.log(arguments[0]);
}

a([1]);

const array = Array.from({ length: 5 }, () => Math.random() > 0.5);

console.log(array);

class StateMachine {
  constructor() {
    this.state = 'idle';
    this.transitions = {
      idle: { start: 'running' },
      running: { pause: 'paused', stop: 'stopped' },
      paused: { resume: 'running', stop: 'stopped' },
      stopped: { reset: 'idle' }
    };
  }
  
  transition(action) {
    const next = this.transitions[this.state]?.[action];
    if (next) this.state = next;
    return this.state;
  }
}

const sm = new StateMachine();
console.log(sm.transition('start'));
console.log(sm.transition('invalid'));
console.log(sm.transition('pause'));
console.log(sm.transition('resume'));
console.log(sm.transition('stop'));
console.log(sm.transition('reset'));

function* generator() {
  yield 1;
  yield 2;
  yield 3;
}

const gen = generator();

const { value, done } = gen.return('early');

console.log(value, done);

const user = {
   name: 'John',
   age: 35,
};

for (const value in user) {
   console.log(value);
}

console.log('1');

setTimeout(() => console.log('2'), 0);

Promise.resolve().then(() => console.log('3'));

setTimeout(() => console.log('4'), 0);

Promise.resolve().then(() => {
  console.log('5');
  return Promise.resolve();
}).then(() => console.log('6'));

console.log('7');

const promise = new Promise((resolve, reject) => {
  setTimeout(() => reject(new Error('Error')), 1000);
});

promise
  .then(result => console.log(result))
  .then(result => console.log(result))
  .catch(error => console.error(error.message))
  .finally(() => console.log('Finally'));

console.log('Start');

setTimeout(() => console.log('Timeout 1'), 0);

setTimeout(() => console.log('Timeout 2'), 0);

console.log('End');

const nums = [1, 2, 3];
const obj = { a: 1, b: 2, c: 3 };

function process(...args) {
  const [first, ...rest] = args;
  const { a, ...others } = obj;
  return { first, rest, a, others };
}

const result = process(...nums);
console.log(result.first);
console.log(result.rest.length);
console.log(result.others.b);
console.log(Object.keys(result.others).join(''));
console.log(result.a === nums[0]);

const array = [1, 2, 3, 4];
const result = array.reduceRight((acc, val) => acc - val);

console.log(result);

let obj = { name: 'Sarah', age: 25 };
let weakMap = new WeakMap();
let map = new Map();

weakMap.set(obj, 'weak reference');
map.set(obj, 'strong reference');

console.log(weakMap.has(obj));
console.log(map.has(obj));

obj = null;

console.log(weakMap.has(null));
console.log(map.has(null));
console.log(map.size);

var b = 10;
if (b % 3 == 0) {
   var i = 10;
}
console.log(i);

const x = [1, 2, 3, 4, 5];
console.log(x.slice(1, 3));

function* fibonacci() {
  let [a, b] = [0, 1];
  while (true) {
    yield a;
    [a, b] = [b, a + b];
  }
}

function* takeWhile(generator, predicate) {
  for (const value of generator) {
    if (!predicate(value)) break;
    yield value;
  }
}

const fib = fibonacci();
const smallFibs = takeWhile(fib, x => x < 20);
console.log([...smallFibs].join(','));

let obj = { a: 1 };
Object.freeze(obj);

console.log(Object.isFrozen(obj));
console.log(obj.a = 2);
console.log(obj.a);

const user = {
  name: 'Sarah',
  age: 25,
  getName() { return this.name; },
  getAge: () => this.age
};

const methods = {
  regular: user.getName,
  arrow: user.getAge
};

console.log(methods.regular());
console.log(methods.arrow());
console.log(user.getName());
console.log(user.getAge());

let obj1 = { name: 'Sarah' };
let obj2 = { name: 'Mike' };
let obj3 = { ref: obj1 };

obj1.circular = obj1;
obj2.partner = obj3;
obj3.partner = obj2;

let weakMap = new WeakMap();
weakMap.set(obj1, 'data1');
weakMap.set(obj2, 'data2');

obj1 = null;
obj2 = null;

console.log(weakMap.has(obj3.ref));
console.log(obj3.partner.name);

var str="My name is John";
var words1=str.split(" ",3);
console.log("words1:",words1);
var words2=str.split(" ",5);
console.log("words2:",words2);

function createCounter() {
  let count = 0;
  return {
    increment: () => ++count,
    decrement: () => --count,
    get: () => count
  };
}

const counter1 = createCounter();
const counter2 = createCounter();
counter1.increment();
counter1.increment();
counter2.increment();
console.log(counter1.get(), counter2.get());
const { increment, get } = counter1;
increment();
console.log(get());

async function foo() {
  console.log('Start');
  await Promise.resolve().then(() => {
    console.log('Inside Promise');
  });
  console.log('End');
}

foo();
console.log('Outside');