JavaScript

function* gen() {
  yield* [1, 2, 3].map(x => x * 2);
}

const iterator = gen();
console.log(iterator.next().value);
console.log(iterator.next().value);
console.log(iterator.next().value);
console.log(iterator.next().value);

async function process() {
  console.log('Start');
  await new Promise(resolve => setTimeout(resolve, 0));
  console.log('Middle');
  return 'Done';
}

process().then(result => console.log(result));
console.log('End');

const obj = Object.freeze({
  a: [1, 2, 3],
  b: {
    c: 4
  }
});

obj.a.push(4);
obj.b.c = 5;

console.log(obj.a);
console.log(obj.b.c);

function outer() {
  var x = 1;
  
  function inner() {
    var x = 2;
    
    function deeper() {
      console.log(x);
    }
    
    return deeper;
  }
  
  return inner();
}

const fn = outer();
fn();

let num = 5;

function change() {
  let num = 10;
  return function() {
    return num;
  };
}

const getValue = change();
num = 20;

console.log(getValue());

const obj = {
  num: 10,
  getValue() {
    return this.num;
  },
  getUpdatedValue() {
    return (() => this.num + 10)();
  }
};

console.log(obj.getValue());
console.log(obj.getUpdatedValue());