Add getCurrentOpenedExpandedDepth to the table api

[RichardHpa]

There is already a table.getExpandedDepth() function in api but if you multiple nested expanded rows and they are all open (lets then say the getExpandedDepth() = 2). If you close the parent of that nested row then getExpandedDepth will still be 2 even though they arent visible right now.

What would be great is to also have a function that returns the max depth for the currently expanded rows. So in my example above. if I close the parent. getExpandedDepth would still be 2. but getCurrentOpenedExpandedDepth would then be 0.

naming can be different its just the first thing I have come up with

[yudin-s]

I think the difference is that getExpandedDepth() is based on expansion state, while what you want is based on the currently visible expanded row tree.

You can compute that from the row model that the table is actually rendering:

function getVisibleExpandedDepth(rows, depth = 0): number {
  let max = 0

  for (const row of rows) {
    if (row.getIsExpanded() && row.subRows?.length) {
      max = Math.max(max, depth + 1, getVisibleExpandedDepth(row.subRows, depth + 1))
    }
  }

  return max
}

const depth = getVisibleExpandedDepth(table.getRowModel().rows)

Because this starts from table.getRowModel().rows, collapsed parent branches are not traversed as visible opened branches. That gives you the “currently opened/visible” depth rather than the deepest id that still exists in the expansion state.

If this were added to the API, I would expect it to be named around visible rows, maybe getVisibleExpandedDepth, because that describes the difference from getExpandedDepth() more directly.

[RichardHpa]

I already have a fix for this up in a PR #6116.