ladybird/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read-min.html

<script src="../include.js"></script>
<script>
    const CHUNK1 = "This -⌄";
    const CHUNK2 = " will not be processed as one chunk";
    const CHUNK3 = "This ->";
    const CHUNK4 = " will be processed as one chunk";
    const CHUNK5 = "WHF!";

    // A read is fulfilled when there are N or more elements available in the stream.
    // We start off by allowing a read to be fulfilled with 1 element available.
    let minElementsAvailable = 1;
    let pullCount = 0;
    const readableStream = new ReadableStream({
        start(controller) {

        },
        pull(controller) {
            ++pullCount;
            const encoder = new TextEncoder();
            if (pullCount === 1) {
                controller.enqueue(encoder.encode(CHUNK1));
            } else if (pullCount === 2) {
                controller.enqueue(encoder.encode(CHUNK2));
            } else if (pullCount === 3) {
                controller.enqueue(encoder.encode(CHUNK3));
            } else if (pullCount === 4) {
                controller.enqueue(encoder.encode(CHUNK4));
                // FIXME: Move/remove this controller.close() when we resolve the FIXME right below.
                controller.close();
            }
            // FIXME: This should have been fulfilled since we are closing the controller at this point, currently we do not.
            //} else if (pullCount === 5) {
                // controller.enqueue(encoder.encode(CHUNK5));
                // controller.close();
            //}

            // Now a read will only be fulfilled when at least 8 elements is available in the stream.
            if (pullCount === 2) {
                minElementsAvailable = 8;
            }
        },
        type: "bytes",
    });

    async function readStream(stream) {
        const reader = stream.getReader({ mode: "byob" });

        let buffer = new ArrayBuffer(200);
        let offset = 0;
        let byteLength = 40;
        while (true) {
            let result = await reader.read(new Uint8Array(buffer, offset, byteLength), { min: minElementsAvailable });
            if (result.done) {
                println("Stream closed");
                break;
            }
            println(new TextDecoder().decode(result.value));

            buffer = result.value.buffer;
            offset += result.value.byteLength;
        }
    }

    asyncTest(async done => {
        await readStream(readableStream);
        done();
    });
</script>