Wrapping algorithm for callback arrow functions adds a comma to the arguments list

Version: 0.0.5 (npm@latest); also 0.0.4, and prettier-browser.

Example: (prettier-browser)

func('a very very very very long long long name that exceeds the width limit', () => {
  return true;
})

// becomes 

func('a very very very very long long long name that exceeds the width limit', (
  ,
) => 
  {
    return true;
  });

Where did the comma in the arguments list come from?

It doesn’t happen with shorter functions that don’t exceed the line length limit, nor with a function callback.

// input
func('a short name', () => {
  return true;
})

// output
func('a short name', () => {
  return true;
});

// input
func('a very very very very long long long name that exceeds the width limit', function() {
  return true;
})

// output
func(
  'a very very very very long long long name that exceeds the width limit',
  function() {
    return true;
  },
);

Side-note: The output for the incorrect function causes prettier to throw an error: prettier-browser. Is the comma actually illegal there, or should I file that as a separate bug?

---

This looks like a wonderful tool. I’m really excited to see where it leads.

[jlongster]

I think we might allow the trailingComma option to have two types, one where it prints them everywhere and another that doesn’t print them in function args.

[erbridge]

If I understand #210 correctly, it resolves the zero argument case, but what about the trailing comma on argument lists?