What are iterators in JavaScript and how do I use them?

What are iterators in JavaScript and how do I use them?

Iterators are objects that allow you to traverse through a collection, like arrays or strings, one element at a time. You can use the next() method to get the next value.

Can you show me an example of creating a custom iterator?

Sure! Here's a simple example:

function createIterator(array) {
    let index = 0;
    return {
        next: function() {
            if (index < array.length) {
                return { value: array[index++], done: false };
            } else {
                return { done: true };
            }
        }
    };
}

const myIterator = createIterator([1, 2, 3]);
console.log(myIterator.next()); // { value: 1, done: false }
console.log(myIterator.next()); // { value: 2, done: false }
console.log(myIterator.next()); // { value: 3, done: false }
console.log(myIterator.next()); // { done: true }

What is the difference between an iterator and an iterable?

An iterable is an object that can be iterated over, like arrays or strings, and it has a Symbol.iterator method. An iterator, on the other hand, is the object that actually performs the iteration, providing the next() method.

How can I use the for...of loop with iterators?

You can use the for...of loop to iterate over any iterable. For example:

const array = [1, 2, 3];
for (const value of array) {
    console.log(value);
}
// Output: 1, 2, 3