Function getPreviousPageElement

packages/react/src/TreeView/useRovingTabIndex.ts:243–260

(element: HTMLElement)

}

function getPreviousPageElement(element: HTMLElement): HTMLElement | undefined {
  const root = element.closest('[role="tree"]')
  if (!root) {
    return
  }

  const items = Array.from(root.querySelectorAll('[role="treeitem"]')) as HTMLElement[]
  if (items.length === 0) {
    return
  }

  const itemLabel = items[0].firstElementChild as HTMLElement
  const pageSize = getPageSize(root, itemLabel)
  const page = Math.floor(items.indexOf(element) / pageSize)
  const offset = items.indexOf(element) - pageSize * page

  return items[Math.max(0, (page - 1) * pageSize + offset)]
}