listitemjoin.js

    {
      match: (node) => {
        return node.kind == 'document'
      },
      validate: (document) => {
        let previousNodeType = null
        const joinableNode = document.nodes.find((node, key) => {
          if (node.type === 'ordered-list' || node.type === 'unordered-list') {
            console.log(node.type)
            if (previousNodeType === node.type) {
              return true
            } else {
              previousNodeType = node.type
              return false
            }
          } else {
            previousNodeType = null
            return false
          }
        })
        if ( joinableNode ) {
          const previousNode = document.getPreviousSibling(joinableNode.key)
          return { previousNode, joinableNode }
        } else {
          return false
        }
      },
      normalize: (transform, document, nodes) => {
        const { joinableNode, previousNode } = nodes
        const size = previousNode.nodes.size
        const listItems = joinableNode.nodes

        listItems.forEach((node, index) => {
          transform.moveNodeByKey(node.key, previousNode.key, size + 1 + index)
        })
        return transform.removeNodeByKey(joinableNode.key)
      }
    }