Just playing around with iterators

LinkedList.js

class LinkedList {
  constructor(value) {
    this.value = value;
    this.next = null;
  }

  push(value) {
    let end = this;
    while (end.next) {
      end = end.next;
    }
    end.next = new LinkedList(value);
  }

  map(fn) {
    let i = 0;
    let head;
    let cur;
    for (const value of this) {
      const result = new LinkedList(fn(value, i));
      if (!head) {
        head = result;
        cur = head;
      } else {
        cur.next = result;
        cur = cur.next;
      }      
    }

    return head;
  }
}

LinkedList.fromArray = (array) => {
  let head = new LinkedList(array[0]);
  curr = head;
  for (let i = 1; i < array.length; i++) {
    curr.next = new LinkedList(array[i]);
    curr = curr.next;
  }
  return head;
};

LinkedList.prototype[Symbol.iterator] = function* () {
  let head = this;
  yield head.value;
  while (head = head.next) {
    yield head.value;
  }
};

// const list = LinkedList.fromArray([1,2,3,4,5]).map(n => `${n} * ${n} = ${n*n}`);
//
// for (const value of list) {
//   console.log(value);
// }