Async function FileReader issue - console.log() array works fine but shows length as 0

Question

async function parseFile(file, type) {
  const fileSize = file.size;
  const chunkSize = 1024 * 1024; // bytes
  let offset = 0;
  let chunkReaderBlock = null;
  const hash = sha1.create();
  const ansList = [];

  const readEventHandler = async function (evt) {
    if (evt.target.error == null) {
      offset += evt.target.result.length;
      await hash.update(evt.target.result);
    } else {
      console.log('Read error: ' + evt.target.error);
      return;
    }
    if (offset >= fileSize) {
      const ans = await hash.hex();
      console.log(ans);
      ansList.push(ans);
      if (type.localeCompare('multiple') === 0) {
        filesUploadHashes.PostFiles.push(ans);
      } else {
        filesUploadHashes.Thumbnail.push(ans);
      }
      return;
    }

    // of to the next chunk
    await chunkReaderBlock(offset, chunkSize, file);
    return ansList;
  };

  chunkReaderBlock = async function (_offset, length, _file) {
    const reader = new FileReader();
    const blob = await _file.slice(_offset, length + _offset);
    reader.onload = readEventHandler;
    await reader.readAsText(blob);
  };

  // read with the first block
  await chunkReaderBlock(offset, chunkSize, file);
  return ansList;
}

parseFile() fucntion takes in a file and reads it chunk by chunk(using offset) by FileReader calculating the sha1 hash. The hash when done calculated is being pushed to ansList array. When printing the array, the output is fine but the length is coming out to be 0.

const ansList = await parseFile(e.target.files[0], '');
console.log(ansList, ansList.length);