Using Symbol.iterator, you can create custom iterators that can be used inside of for loops and Array spreads. This lesson walks you through creating a function to create iterators from arrays that you pass into the function.
const abcs = ["A", "B", "C"] const numbers = [1, 2, 3] const createReverseIterator = array => ({ [Symbol.iterator]() { let i = array.length return { next: () => ({ value: array[--i], done: i < 0 }) } } }) for (let value of createReverseIterator(numbers)) { console.log(value) }
[Javascript] Create a Custom Iterator for Any Array
原文：https://www.cnblogs.com/Answer1215/p/12111188.html