transformsync.js

/**
 * @param {import('stream').Transform} stream
 * @param {string} data
 */
function transformSync(stream, data) {
  if (data.length > stream.writableHighWaterMark) {
    throw new Error('Data is too large for  synchronous transform');
  }
  let done = false;
  stream.write(data, (err) => {
    if (err) {
      throw err;
    } else {
      done = true;
    }
  });
  /** @type Array<string | object> */
  const results = [];
  stream.on('data', (chunk) => results.push(chunk));
  if (!done) {
    throw new Error('Stream did not flush after write');
  }
  return results;
}