Note: This feature is available in Web Workers.
The closed read-only property of the WritableStreamDefaultWriter interface returns a Promise that fulfills if the stream becomes closed, or rejects if the stream errors or the writer's lock is released.
A Promise.
const writableStream = new WritableStream(
{
start(controller) {},
write(chunk, controller) {
// …
},
close(controller) {
// …
},
abort(err) {
// …
},
},
queuingStrategy,
);
// …
const writer = writableStream.getWriter();
// ..
// check if the stream is closed
writer.closed.then(() => {
console.log("writer closed");
});