Instance or static methods for non-operator calculations?

[littledan]

Fabrice Bellard's BigDecimal implementation in QuickJS (2020-01-05 release) uses static methods like BigDecimal.div rather than instance methods like BigDecimal.prototype.div, as the current README suggests. In personal communication, Fabrice said,

Regarding BigDecimal.prototype.div / BigDecimal.div, I tend to prefer
BigDecimal.div because both operands play the same role. It is a matter
of personal taste anyway.

BigDecimal.round is also a static method in QuickJS, and an instance method in the current README.

I could go either way on this ergonomics question. I thought instance methods would be easier to type, but I don't have strong feelings.

[ljharb]

When the order of the operands doesn’t matter then static makes more sense to me; when they do, I’d personally lean towards instance methods.

[littledan]

If we add methods for arithmetic operations to give rounding parameters, I think it'd be confusing to make add a static method and sub an instance method. I'd prefer to make a general decision for all arithmetic things, even if some end up being commutative and others not.

[Rudxain]

I think we should stick with the "principle of least surprise" and follow the current ES pattern. This means not all methods would be static or instance. But we should only choose this option if there's no consensus. If we can settle on a consensus that does things in a different way, we should try it, we shouldn't stick to the past just because "it has always been this way".

My personal opinion is that frequently used methods should be on the prototype, while "more special" methods are static, this reduces the need for minification in some cases, and saves time for the devs and users