JavaScript Async Iterator

Syntax

async function* createAsyncIterable(syncIterable) {
for (const elem of syncIterable) {
yield elem;
}
}

const asyncIterable = createAsyncIterable([“a”, “b”]);
const asyncIterator = asyncIterableSymbol.asyncIterator;
asyncIterator
.next()
.then((iterResult1) => {
console.log(iterResult1);
return asyncIterator.next();
// { value: ‘a’, done: false }
})
.then((iterResult2) => {
console.log(iterResult2);
return asyncIterator.next();
// { value: ‘b’, done: false }
})
.then((iterResult3) => {
console.log(iterResult3);
// { value: undefined, done: true }
});

TypeScript interfaces

The [TypeScript Interfaces](TypeScript Interfaces), in TypeScript notation:

interface AsyncIterable {
Symbol.asyncIterator: AsyncIterator;
}
interface AsyncIterator {
next(): Promise;
}
interface IteratorResult {
value: any;
done: boolean;
}

See also

• [JavaScript Generators](JavaScript Generators)
• [JavaScript For Await Of](JavaScript For Await Of)