getJson('json/1')
  .then(json => {
    if(json.key) {
      return getJson('json/2')
    }
    throw new Error('No key')
  })
  .then(json => {
    return json.key2
  })
  .catch(e => {
    console.log(e)
  })

function fetchWithRetries(retriesCount, ...fetchArgs) {
    /* */
}

function reduce(array, callback, initial) {
    let acc = initial
    
    for(let i = 0; i < array.length; i++) {
        acc = callback(acc, array[i], i)
    }
    
    return acc
}

compress([1, 4, 3, 2]) // '1-4'

compress([1, 4]) //'1, 4'

class Store {
    /*  */
}
  
  const store = new Store()
  
  const firstSubscriber = (data) => console.log('first', data)
  const secondSubscriber = (data) => console.log('second', data)
  
  store.subscribe(firstSubscriber)
  store.subscribe(secondSubscriber)
  
  store.data = {newKey: 'newString'}
  
  /** CONSOLE
   * first {newKey: 'newString'}
   * second {newKey: 'newString'}
   */
  
  store.unsubsribe(firstSubscriber)
  
    /** CONSOLE
   * second {newKey: 'newString'}
   */
}

setTimeout(() => {
  console.log('setTimeout')
})

const promise = new Promise((resolve, reject) => {
  console.log(1);
  setTimeout(() => {
    console.log("timerStart");
    resolve("success");
    console.log("timerEnd");
  }, 0);

  Promise.resolve().then(() => {
    console.log('resolve')
  })
  console.log(2);
});

promise.then((res) => {
  console.log(res);
});

console.log(4);

setTimeout(function timeout() {
   console.log('Таймаут 1');
}, 0);

let p = new Promise(function(resolve, reject) {
   console.log('Создание промиса');

   setTimeout(function timeout() {
     console.log('Таймаут 2');
   }, 0);

   resolve();
});

p.then(function(){
   console.log('Обработка промиса');
});

console.log('Конец скрипта');

const myPromise = (delay) => new Promise((res, rej) => { setTimeout(res, delay) })

setTimeout(() => console.log('in setTimeout1'), 1000);

myPromise(1000).then(res => console.log('in Promise 1'));

setTimeout(() => console.log('in setTimeout2'), 100);

myPromise(2000).then(res => console.log('in Promise 2'));

setTimeout(() => console.log('in setTimeout3'), 2000);

myPromise(1000).then(res => console.log('in Promise 3'));

setTimeout(() => console.log('in setTimeout4'), 1000);

myPromise(5000).then(res => console.log('in Promise '));

console.log(1); 

setTimeout(() => console.log(2));

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

Promise.resolve().then(() => setTimeout(() => console.log(4)));

Promise.resolve().then(() => console.log(5));

setTimeout(() => Promise.resolve().then(() => console.log(6)));

console.log(7);

console.log('start');

const promise1 = Promise.resolve().then(() => {
    console.log('promise1');
    const timer1 = setTimeout(() => {
        console.log('timer1')
        const promise2 = Promise.resolve().then(() => {
            console.log('promise2');
            const timer2 = setTimeout(() => {
                console.log('timer2')
            }, 0)
        })
    }, 0);
});

const timer3 = setTimeout(() => {
    console.log('timer3');
    const promise3 = new Promise(resolve => {
        setTimeout(() => {
            console.log('promise3');
            resolve();
        }, 0);
    }).then(() => {
        console.log('promise3 then');
    })
}, 0);

async function asyncFunction() {
    console.log('async start');
    await new Promise(resolve => setTimeout(resolve, 0));
    console.log('async middle');
    await Promise.resolve().then(() => console.log('async promise'));
    console.log('async end');
}

asyncFunction();

console.log('end');

console.log('1')
Promise.resolve('2')
    .then((res) => {
      console.log(res);
      
      Promise.resolve('3')
        .then((res) => {
          console.log(res);
          setTimeout(() => {console.log('4')}, 0);
        })    
    })
    .then((res) => console.log(res))
    .finally((res) => {
      console.log(res);
      setTimeout(() => {console.log('5')}, 0);
    });
console.log('6');

console.log('1')
Promise.reject('2')
    .then((res) => {
      console.log(res);
      
      Promise.resolve('3')
        .then((res) => {
          console.log(res);
          setTimeout(() => {console.log('4')}, 0);
        })    
    })
    .catch((res) => console.log(res))
    .then((res) => console.log(res))
    .finally((res) => {
      console.log(res);
      setTimeout(() => {console.log('5')}, 0);
    });
console.log('6');

function foo() {
  const x = 10;

  return {
    x: 20,
    bar: () => {
      console.log(this.x)
    },
    baz: function() {
      console.log(this.x)
    }
  };
}

const obj1 = foo();

obj1.bar();    // ...
obj1.baz();       // ...

const obj2 = foo.call({ x: 30 });
obj2.bar();    // ..
obj2.baz();       // ...

type Rectangle = {
  width: number ;
  height: number ;
};

type Circle = {
  radius: number;
};

type AvailableFigure = Rectangle | Circle;

function isCircle(figure) {
  ...
}

function getCircleArea(figure: Circle): number {
    return Math.pow(figure.radius, 2) * Math.PI
}

function getRectangleArea(figure: Rectangle): number {
    return figure.width * figure.height
}

function getArea(figure: AvailableFigure): number {
  return isCircle(figure)
    ? getCircleArea(figure)
    : getRectangleArea(figure);
}

type MyPick<T, U extends keyof T> = {
    [key in U]: T[key] 
}

import React from 'react';

const elements = Array(16).fill(0);

export default function App() {
  const [randomIndex, setRandomIndex] = React.useState(0);
  const [isStart, setStart] = React.useState(false);

  // Ваш код здесь

  return (
    <div className="App">
      <h1>⭐ Crush the mole ⭐</h1>
      <button onClick={() => { /* Ваш код здесь */ }}>
        {isStart ? "Остановить" : "Начать игру"}
      </button>
      <div className="container">
        {elements.map((elem, index) => (
          <div
            key={index}
            className="item"
            onClick={() => { /* Ваш код здесь */ }}
          >
            {index === randomIndex ? "@" : ""}
          </div>
        ))}
      </div>
    </div>
  );
}