What are iterators in TypeScript?

What are iterators in TypeScript?

Iterators in TypeScript are objects that allow you to traverse through a collection, like arrays or strings, one element at a time.

Can you give me an example of how to create an iterator?

Sure! You can create an iterator by implementing the next() method in an object. Here's a simple example:

class MyIterator {
    private index = 0;
    private data = [1, 2, 3];

    next() {
        if (this.index < this.data.length) {
            return { value: this.data[this.index++], done: false };
        } else {
            return { value: undefined, done: true };
        }
    }
}

const iterator = new MyIterator();
console.log(iterator.next()); // { value: 1, done: false }
console.log(iterator.next()); // { value: 2, done: false }
console.log(iterator.next()); // { value: 3, done: false }
console.log(iterator.next()); // { value: undefined, 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 must implement the Symbol.iterator method. An iterator, on the other hand, is the object that actually performs the iteration, providing the next() method to access the elements.

How can I use built-in iterators in TypeScript?

You can use built-in iterators like those in arrays or maps directly. For example, you can use the for...of loop to iterate over an array:

const arr = [1, 2, 3];
for (const value of arr) {
    console.log(value);
}