Name, values, and shape of show/hide zero values option(s)

[justingrant]

(Follow-up from #32 (comment))

What should the name and shape of the show/hide zeroes option be?

Some questions for discussion:

A) Negative (e.g. hideXxx) vs. positive (showXxx) vs. neutral (e.g. zero)

• Most other APIs seem to use positive options more frequently than negative ones. So I'd suggest either positive or neutral names.

B) One option or three options (one each for leading, trailing, and internal) ?

• AFAICT, showing leading, trailing, and internal zero values are unrelated choices. An 8-value enum to support all permutations is too complex. So unless I'm missing something obvious, I assume this means that using three separate options would be best.

C) Align naming with similar option(s) in other APIs?

• @sffc mentioned one in the meeting but I forget what it was (maybe NumberFormat V3?) that uses a trailing-zeroes option. Seems like a good idea to align.

D) How will these options interact with style?

• For example, the 'digital' style probably requires internal zeroes to be shown, while the 'long' style would allow (or perhaps default to?) hiding internal zeroes.

Taking the questions above into account, here's a few choices. In all cases the default would be 'auto' which means "use the defaults appropriate for the style".

1. Three separate options

{
  trailingZeroFields: 'show' | 'hide' | 'auto';
  leadingZeroFields: 'show' | 'hide' | 'auto';
  internalZeroFields: 'show' | 'hide' | 'auto';
}

2. Nested options

The caller could either apply the same value to all three positions using a single string value, or could choose different values for leading vs. trailing vs. internal by providing an object bag as a value.

{
  zeroFields: 
    'show' | 
    'hide' | 
    'auto' |
    { 
      leading?: 'show' | 'hide' | 'auto';
      trailing?:  'show' | 'hide' | 'auto';
      internal?: 'show' | 'hide' | 'auto';
    };
}

[sffc]

I had some ideas for trailingZero[e]s sketched out in tc39/proposal-intl-numberformat-v3#8. However, I wouldn't use this as any sort of precedent; if anything, NFv3 will follow what DurationFormat chooses.

[ryzokuken]

@sffc @justingrant can we reach consensus on this here or should we take this to the monthly meeting?

[justingrant]

I don't have a strong preference between (1) and (2).

[ryzokuken]

I slightly prefer (1) because (2) seems rather complicated. Also, I would like to restrict "internalZeroFields" in (1) to not accept "hide", for obvious reasons.

If that sounds acceptable to you two, I will remove it from the discussion and just proceed with the specification.

[sffc]

Choice 1 makes the most sense to me.

In NFv3, I am proposing an option named trailongZeroDisplay. Consider using the same name here?

[justingrant]

I slightly prefer (1) because (2) seems rather complicated. Also, I would like to restrict "internalZeroFields" in (1) to not accept "hide", for obvious reasons.

@ryzokuken - Sorry, not obvious to me. Why? For digital formats I understand your point, but for non-digital formats (e.g. "3 hours and 5 seconds") omitting internal zeros should be allowed.

In NFv3, I am proposing an option named trailongZeroDisplay. Consider using the same name here?

I thought a lot about naming. The bikeshed problem is how to differentiate handling zeroes in each field (e.g. 08:12 vs 8:12) vs. hiding entire fields if they're zero. The name should expose the difference. That's why I ended up with xxxZeroFields which I'm not convinced is the best option but I'd worry that trailingZeroDisplay doesn't work hard enough to differentiate the two meanings.

Speaking of naming, I realized that innerZeroFields might be better than internalZeroFields because "internal" has the connotation of calculations not visible to the user (internal logic) while "inner" seems to connote things that users can see.

[ryzokuken]

Sorry, not obvious to me. Why? For digital formats I understand your point, but for non-digital formats (e.g. "3 hours and 5 seconds") omitting internal zeros should be allowed.

Sorry, my bad. I meant to say that I wanted to restrict that only for digital, if I wanted to restrict it everywhere why would we even keep it...

[sffc]

Discussion from 2021-05-07 TC39-TG2 meeting: https://github.com/tc39/ecma402/blob/master/meetings/notes-2021-05-06.md#name-values-and-shape-of-showhide-zero-values-options-40

[ryzokuken]

This has been addressed in the latest version. Closing.