What are generators?

Generators in JavaScript are functions that can be paused and resumed, allowing them to produce values sequentially upon request. They are declared using function* and use the yield keyword to return values.

Main features of generators:

• Enable creating lazy sequences of data.
• Manage the state of the function between calls.
• Can be used for asynchronous programming (together with yield and promises).

Example of a generator that yields numbers from 1 to 3:

function* numbers() {
  yield 1;
  yield 2;
  yield 3;
}

const gen = numbers();
console.log(gen.next()); // { value: 1, done: false }
console.log(gen.next()); // { value: 2, done: false }
console.log(gen.next()); // { value: 3, done: false }
console.log(gen.next()); // { value: undefined, done: true }

Generators are useful for working with data streams, iterators, and asynchronous code.