React: Building Modern Web Applications

The iteration protocols

An iteration protocol is a set of rules that an object needs to follow for implementing the interface, which when used, a loop or a construct can iterate over a group of values of the object.

ES6 introduces two new iteration protocols known as the iterable protocol, and the iterator protocol.

The iterator protocol

Any object that implements the iterator protocol is known as an iterator. According to the iterator protocol, an object needs to provide a next() method that returns the next item in the sequence of a group of items.

Here is an example to demonstrate this:

let obj = { array: [1, 2, 3, 4, 5], nextIndex: 0, next: function(){ return this.nextIndex < this.array.length ? {value: this.array[this.nextIndex++], done: false} ...