serverless-spy
Version:
CDK-based library for writing elegant integration tests on AWS serverless architecture and an additional web console to monitor events in real time.
32 lines (31 loc) • 923 B
JavaScript
export async function headStream(stream, bytes) {
let byteLengthCounter = 0;
const chunks = [];
const reader = stream.getReader();
let isDone = false;
while (!isDone) {
const { done, value } = await reader.read();
if (value) {
chunks.push(value);
byteLengthCounter += value?.byteLength ?? 0;
}
if (byteLengthCounter >= bytes) {
break;
}
isDone = done;
}
reader.releaseLock();
const collected = new Uint8Array(Math.min(bytes, byteLengthCounter));
let offset = 0;
for (const chunk of chunks) {
if (chunk.byteLength > collected.byteLength - offset) {
collected.set(chunk.subarray(0, collected.byteLength - offset), offset);
break;
}
else {
collected.set(chunk, offset);
}
offset += chunk.length;
}
return collected;
}