const countdown = {

  [Symbol.iterator]() {

    const iterator = {

      value: 10,

      done: false,

      next() {

        this.done = this.done || this.value < 0;

​

        if (this.done) {

          return { done: true };

        } else {

          return { done: false, value: this.value-- };

        }

      }

    };

​

    return iterator;

  }

};

​

for (const count of countdown) {

  console.log(count);

}

​

const [ten, nine, eight, ...rest] = countdown;

​

console.log(ten)

  //=> 10

console.log(nine)

  //=> 9

console.log(eight)

  //=> 8

console.log(rest)

  //=> [7, 6, 5, 4, 3, 2, 1]