code: function splitLastKey (path) {
    let pathArr = path.split('.')
    if (pathArr.length >= 2) {
      let patentObjectPath = pathArr.splice(0, pathArr.length - 1) || []// pathArr -> key
      return [pathArr, patentObjectPath.join('.')]
    } else {
      return [pathArr]
    }
  }
docs: Split path string to [pathLastKey, pathParent]
  @param {String} path - update path
  @return {Array} pathPair - Array of [key,parentPath]