_previousNode () {
    let prevNode = null
    const dom = this.getDom()
    if (dom && dom.parentNode) {
      // find the previous field
      let prevDom = dom
      do {
        prevDom = prevDom.previousSibling
        prevNode = Node.getNodeFromTarget(prevDom)
      }
      while (prevDom && prevNode && (prevNode instanceof AppendNode && !prevNode.isVisible()))
    }
    return prevNode
  }
Get the previously rendered node
@return {Node | null} previousNode