Should function declaration in catch be allowed?

[davidpfahler]

I got Move function declaration to function body root. error for the following code:

initialise()
function initialise () {
  try {
    return nativeImplementation()
  } catch (e) {
    function fakeImplementation () {
      // ...
    }

    return fakeImplementation()
  }
}

I was intentionally declaring the fakeImplementation function in the catch block, because I though it to be a waste to declare the function if it is most likely never being used. Isn't this an anti-pattern?

[julien-f]

Function declarations are hoisted (automatically moved to the top of the scope) so your fakeImplementation() function is always created.

What you want is to use a function expression assigned to a variable:

initialise()
function initialise () {
  try {
    return nativeImplementation()
  } catch (e) {
    var fakeImplementation = function () {
      // ...
    }

    return fakeImplementation()
  }
}

[feross]

What @julien-f said is correct. The error message could be more helpful, but I think we should keep this rule in place. I'm going to close this issue. Feel free to continue discussing if you want.