Iterator Design pattern

 // Iterator Interface

class Iterator {

constructor(collection) {

this.collection = collection;

this.index = 0;

}

next() {

const item = this.collection[this.index];

this.index++;

return item;

}

hasNext() {

return this.index < this.collection.length;

}

}

// Concrete Aggregate

class ListAggregate {

constructor() {

this.items = [];

}

addItem(item) {

this.items.push(item);

}

createIterator() {

return new Iterator(this.items);

}

}

// Client code

const aggregate = new ListAggregate();

aggregate.addItem("Item 1");

aggregate.addItem("Item 2");

const iterator = aggregate.createIterator();

while (iterator.hasNext()) {

console.log(iterator.next());

}