Can I use
?

let

- OTHER

Declares a variable with block level scope

Chrome

  1. 4 - 18: Not supported
  2. 19 - 40: Disabled by default
  3. 41 - 48: Partial support
  4. 49 - 105: Supported
  5. 106: Supported
  6. 107 - 109: Supported

Edge

  1. 12 - 105: Supported
  2. 106: Supported

Safari

  1. 3.1 - 9.1: Not supported
  2. 10 - 10.1: Partial support
  3. 11 - 15.6: Supported
  4. 16.0: Supported
  5. 16.1 - TP: Supported

Firefox

  1. 2 - 43: Disabled by default
  2. 44 - 104: Supported
  3. 105: Supported
  4. 106 - 107: Supported

Opera

  1. 9 - 12.1: Not supported
  2. 15 - 27: Disabled by default
  3. 28 - 35: Partial support
  4. 36 - 90: Supported
  5. 91: Supported

IE

  1. 5.5 - 10: Not supported
  2. 11: Partial support

Chrome for Android

  1. 106: Supported

Safari on iOS

  1. 3.2 - 9.3: Not supported
  2. 10 - 10.3: Partial support
  3. 11 - 15.6: Supported
  4. 16.0: Supported
  5. 16.1: Supported

Samsung Internet

  1. 4: Partial support
  2. 5 - 17.0: Supported
  3. 18.0: Supported

Opera Mini

  1. all: Not supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 64: Supported

UC Browser for Android

  1. 13.4: Supported

Android Browser

  1. 2.1 - 4.4.4: Not supported
  2. 106: Supported

Firefox for Android

  1. 105: Supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: Supported

KaiOS Browser

  1. 2.5: Supported
Resources:
MDN Web Docs - let
Variables and Constants in ES6