extra-dom/src/previous-sibling.ts

Utilities for DOM

import { assert } from '@blackglory/errors'

export function previousSibling(node: Node, distance: number = 1): ChildNode | undefined {
  assert(Number.isInteger(distance), 'parameter distance must be an integer')
  assert(distance >= 1, 'parameter distance must be greater than or equal to 1')

  return previousSibling(node, distance)

  function previousSibling(node: Node, distance: number = 1): ChildNode | undefined {
    const currentNode = node.previousSibling
    if (!currentNode) return undefined

    if (distance === 1) {
      return currentNode
    } else {
      return previousSibling(currentNode, distance - 1)
    }
  }
}