Previous node for first node of child variations

[mbutsykin]

Maybe it's better to return "parent's" previous node for children variations?

const game = new kokopu.Game();

const e4 = game.mainVariation().play('e4');
const e5 = e4.play('e5')

const e6 = e5.addVariation().play('e6')

e6.previous(); // for now - it's undefined but maybe return e4?

[yo35]

I considered implementing it like this, but I wanted to have an API that exposes clearly that the beginning of a sub-variation has been reached. Also, in this way, .next() and .previous() are "symmetric", in the sense that aNode.next().previous() === aNode aNode.previous().next() === aNode (assuming that aNode has a parent and a child). With the implementation you propose, it would be possible to have aNode.previous().next() returns something different from aNode.

[mbutsykin]

i see, sounds logical) but after you implemented "id" for nodes - imho there is no need in comparing instances directly.

for example here is my UI

you can navigate "back" and "forward" with arrows at the bottom

for current implementation

for "forward" you can do as simple as that:

const [current, setCurrent] = useState<Node>()

function handleNextClick() {
  setCurrent(current.next());
}

for "back":

const [current, setCurrent] = useState<Node>()

function handlePrevClick() {
  setCurrent(getPrevious(current));
}

function getPrevious(node) {

  let previous = node.previous()

  if (previous) {
    return previous;
  }

  const parent = node.parentVariation().parentNode();

  if (parent) {
    return getPrevious(parent);  
  }

  return undefined;
}

seems a bit overwhelmed =/ but i guess it's still fine, just wanted to have it somehow "consistent" your point is definitely valid and it's up to you of course)

[mbutsykin]

btw, i appreciate your work a lot! i have an app for iOS (for iPhone & iPad) that's using your library a lot) can i somehow gift it for you? i can generate "promo code" (redeem in appstore) and send it to you somewhere

[yo35]

Thanks for your enthusiasm and your proposal. Unfortunately, I'm on the Android-side of the Force, thus I won't be able to test your app. ;-)