'let block' is only available in Mozilla JavaScript extensions (use moz option)

Question

I am trying the simple code below, but it is throwing the following error

'let block' is only available in Mozilla JavaScript extensions (use moz option)

let (a=20,b,c) {
  console.log(a,b,c);
}

What is the reason for this error?

Answer 1

let block is non-standardized and specific to Gecko (it has been also deprecated and removed).

JSHint requires to enable Gecko-only features with moz option.

The standard way to do this is

{
  let a=20,b,c;
  console.log(a,b,c);
}