read-excel-file/modules/export/unpackXlsxFileBrowser.js

Read `.xlsx` files in a web browser or in Node.js

// Here it uses the "async" version of the unzipper function
// just because it unzips the files inside an archive in parallel
// rather than sequentially. It uses web workers for that.
// Smaller files are still handled synchronously under the hood.
//
// It did condict a couple of basic manual tests in a web browser
// and the results showed that a `1 MB` `.xlsx` file is read in `100 ms`
// both using "sync" and "async" versions of the unzipper function,
// and reading a `200 KB` `.xlsx` file is done in `70 ms` when using
// the "sync" version and in `80 ms" when using the "async" verison.
//
// So the "sync" version of the unzipper function is faster on smaller file sizes
// of about < 1 MB. Still, the rest of the parsing code smoothes out this difference,
// and the end result is not much different. Does the difference of `10 ms` justify
// the mental overhead of choosing the right variant for a file of a given size?
// I'd say "not really". Sure, performance fans wouldn't scuff on those `10 ms`
// but it's literally "a blink of an eye" and about a duration of a single frame
// on a 120 FPS screen.
//
// Hence, it simply uses the "async" variant of the unzipper function in any case.
//
// import unzipFromArrayBufferSync from '../zip/unzipFromArrayBufferSync.js'
import unzipFromArrayBuffer from '../zip/unzipFromArrayBuffer.js';
import UnzipError from '../zip/UnzipError.js';
import InvalidInputError from '../xlsx/file/InvalidInputError.js';
import filterZipArchiveEntry from './filterZipArchiveEntry.js';
import validateLeadingBytes from '../xlsx/file/validateLeadingBytes.js';
import checkpoint, { resetCheckpoint } from '../utility/checkpoint.js';

/**
 * Unpacks `*.xlsx` file contents.
 * An `.xlsx` file is really just a `.zip` archive with `.xml` files inside.
 * @param  {(File|Blob|ArrayBuffer)} input
 * @return {Promise<Record<string,Uint8Array>} Resolves to an object holding `*.xlsx` file entries.
 */
export default function unpackXlsxFile(input) {
  resetCheckpoint();
  checkpoint('unpack files');
  if (input instanceof File || input instanceof Blob) {
    return input.arrayBuffer().then(getResultFromArrayBuffer);
  }
  return Promise.resolve(input).then(getResultFromArrayBuffer);
}
function getResultFromArrayBuffer(arrayBuffer) {
  validateLeadingBytes(new Uint8Array(arrayBuffer));
  return unzipFromArrayBuffer(arrayBuffer, {
    filter: filterZipArchiveEntry
  }).then(function (result) {
    return result;
  }, function (error) {
    if (error instanceof UnzipError) {
      throw new InvalidInputError('INVALID_ZIP', error.cause);
    } else {
      throw error;
    }
  });
}

// function getResultFromArrayBuffer(arrayBuffer) {
// 	const result = unzipFromArrayBufferSync(arrayBuffer, { filter: filterZipArchiveEntry })
// 	return Promise.resolve(result)
// }
//# sourceMappingURL=unpackXlsxFileBrowser.js.map