Iterator

• What is this?
• https://qiita.com/kura07/items/cf168a7ea20e8c2554c6

  • When the [Symbol.iterator]() method is executed, it returns an iterator.

    • What is Symbol?
  • It seems that each time iterator.next() is called, the next value is returned.
  • If an object follows the protocol of this Iterator,
    • you can write for (var v of obj) { do something }
    • Spread Operator also supports iterators.
    • Oh, so arrays and strings also have iterators.
      • And you can write the same way with custom classes, which is nice.
• What is Generator?