Can I use
?

FileReaderSync

- WD

Allows files to be read synchronously in Web Workers

Chrome

  1. 4 - 14: Support unknown
  2. 15 - 112: Supported
  3. 113: Supported
  4. 114 - 116: Supported

Edge

  1. 12 - 112: Supported
  2. 113: Supported

Safari

  1. 3.1 - 5.1: Not supported
  2. 6 - 16.4: Supported
  3. 16.5: Supported
  4. 16.6 - TP: Supported

Firefox

  1. 2 - 7: Not supported
  2. 8 - 112: Supported
  3. 113: Supported
  4. 114 - 115: Supported

Opera

  1. 9 - 10.1: Not supported
  2. 10.5 - 11.5: Support unknown
  3. 11.6 - 98: Supported
  4. 99: Supported

IE

  1. 5.5 - 9: Not supported
  2. 10: Supported
  3. 11: Supported

Chrome for Android

  1. 113: Supported

Safari on iOS

  1. 3.2 - 5.1: Not supported
  2. 6 - 16.4: Supported
  3. 16.5: Supported

Samsung Internet

  1. 4 - 20: Supported
  2. 21: Supported

Opera Mini

  1. all: Not supported

Opera Mobile

  1. 10: Not supported
  2. 11 - 11.1: Support unknown
  3. 11.5 - 12.1: Supported
  4. 73: Supported

UC Browser for Android

  1. 13.4: Supported

Android Browser

  1. 2.1 - 4.3: Not supported
  2. 4.4 - 4.4.4: Supported
  3. 113: Supported

Firefox for Android

  1. 113: Supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: Supported

KaiOS Browser

  1. 2.5: Supported
  2. 3: Supported
Resources:
MDN Web Docs - FileReaderSync