What are custom iterators in JavaScript?

What are custom iterators in JavaScript?

Custom iterators in JavaScript allow you to define how an object can be iterated over, using the Symbol.iterator method.

Can you show me an example of a custom iterator?

Sure! Here's a simple example:

class MyArray {
    constructor(...elements) {
        this.elements = elements;
    }
    [Symbol.iterator]() {
        let index = 0;
        return {
            next: () => {
                if (index < this.elements.length) {
                    return { value: this.elements[index++], done: false };
                } else {
                    return { done: true };
                }
            }
        };
    }
}

const myArray = new MyArray(1, 2, 3);
for (const value of myArray) {
    console.log(value);
}

What are the benefits of using custom iterators?

Custom iterators provide more control over the iteration process, allowing you to define specific behaviors, such as filtering or transforming data during iteration.

Can custom iterators be used with async functions?

Yes, you can create async iterators using the Symbol.asyncIterator method, which allows you to work with asynchronous data sources.