Bug: no-var autofix is not working

[mvorisek]

How to reproduce?

config:

'no-var': ['error']

code:

var fx = function (i = 0) {
  if (i < 5) {
    return fx(i + 1);
  }
  console.log(i);
};

fx();

What did you expect to happen?

var fx autofixed to let fx

I tried the code in a sandpit and it behaves the same.

What actually happened?

not autofixed, Unexpected var, use let or const instead no-var error is generated

(autofix of var -> let works in other cases, the problem is present only when the variable is referred in anonymous function in the same declaration)

[mdjermanovic]

Hi @mvorisek, thank for the issue!

I can reproduce this. The variable is referenced in its initializer, so the rule considers the fix unsafe because the reference might be evaluated in TDZ. I think we can make a small change to ignore the reference if the initializer is a function definition, as in that case the reference certainly cannot be evaluated in TDZ. I'm working on the fix.

[amareshsm]

@mdjermanovic I would like to give it a try. Can I work on this?

ignore the reference if the initializer is a function definition

Like this?

    if (!declarator.init || declarator.init.type === 'FunctionExpression') {
                return false;
    }

[mdjermanovic]

Ah, I've already started working on this and prepared PR #16611.