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cancel(reason)
The cancel() method of the
ReadableStream interface returns a Promise that resolves when the stream is canceled.
Cancel is used when you’ve completely finished with the stream and don’t need any more data from it, even if chunks are enqueued waiting to be read. That data is lost after cancel is called, and the stream is not readable any more. To close the stream without getting rid of enqueued chunks, use
ReadableStreamDefaultController.close().
Arguments
Return value
A promise that resolves with the value undefined when the stream is canceled.
Exceptions
Example
import { ReadableStream } from 'k6/experimental/streams';
import { setTimeout } from 'k6/timers';
export default async function () {
// Define a number stream that emits numbers from 1 to 10 every second
const stream = numbersStream();
const reader = stream.getReader();
while (true) {
const { done, value } = await reader.read();
if (done) break;
if (value === 8) {
// Cancel the stream when the number is 8, any enqueued chunks are lost
await reader.cancel('cancelling the stream');
break;
}
}
}
function numbersStream() {
let currentNumber = 0;
return new ReadableStream({
start(controller) {
const fn = () => {
if (currentNumber < 10) {
controller.enqueue(++currentNumber);
setTimeout(fn, 1000);
return;
}
controller.close();
};
setTimeout(fn, 1000);
},
});
}
