[Javascript] Convert a forEach method to generator

For example we have a 'forEach' method which can loop though a linked list:

forEach(fn) {
    let node = this.head;
    let counter = ;
    while (node) {
      fn(node, counter);
      node = node.next;
      counter++;
    }
  }

Test:

test('applies a transform to each node', () => {
    const l = new List();

    l.insertLast();
    l.insertLast();
    l.insertLast();
    l.insertLast();

    l.forEach(node => {
      node.data += ;
    });

    expect(l.getAt().data).toEqual();
    expect(l.getAt().data).toEqual();
    expect(l.getAt().data).toEqual();
    expect(l.getAt().data).toEqual();
  });

What if we want to use for...of loop? Then we need to convert LinkedList to support generator partten, the usage of for..of:

test('works with the linked list', () => {
    const l = new List();

    l.insertLast();
    l.insertLast();
    l.insertLast();
    l.insertLast();

    for (let node of l) {
      node.data += ;
    }

    expect(l.getAt().data).toEqual();
    expect(l.getAt().data).toEqual();
    expect(l.getAt().data).toEqual();
    expect(l.getAt().data).toEqual();
  });

Implementation:

*[Symbol.iterator]() {
    let node = this.head;
    while (node) {
      yield node;
      node = node.next;
    }
  }