Паттерны Iterator и Observer

// Iterator Patter
var iterator = getNumbers();
console.log(iterator.next()); // {value: 1, done: false}
console.log(iterator.next()); // {value: 2, done: false}
console.log(iterator.next()); // {value: 3, done: false}

// Observer Pattern
document.addEventListener(
      'mousemove'
    , function next (event) {
        console.log(event);
      }
);

// {clientX: 425, clientY: 543}
// {clientX: 450, clientY: 558}
// {clientX: 455, clientY: 562}

document.removeEventListener('mousemove', next);