Async iterators — for await...of and async generators
Use async generators and for await...of to consume values that arrive over time. Learn Symbol.asyncIterator and simple async pipelines.
Why async iteration?
Goal: Consume values that may come later.
- for await...of loops over async iterables
- async function* creates async generators
- Symbol.asyncIterator marks an object as async-iterable
- Tiny async map example
async function* and for await...of
An async generator (async function*) yields values that for await...of consumes.
// Use an async generator to yield values (could be delayed in real apps)
(async function () {
async function* countAsync(n) {
for (let i = 1; i <= n; i = i + 1) {
// In real code you could await a delay or I/O here
yield i;
}
}
for await (const x of countAsync(3)) {
console.log("async value:", x);
}
})();
All lessons in this course
- Iterable protocol and for...of
- Generator functions, yield, and small pipelines
- Async iterators — for await...of and async generators