Combine commands on the ProseMirror undo stack

prosemirror-history-combine-commands.ts

/**
* Given two commands (commandA and commandB), returns a new command that when applied 
* to a ProseMirror state that uses the prosemirror-history plugin applies commandA and 
* then commandB so that both commands are undone with a single undo action. 
**/
const combineCommands =
  (commandA: Command, commandB: Command) =>
  (state: EditorState, dispatch?: (tr: Transaction) => void): boolean => {
    return commandA(state, (transactionA: Transaction) => {
      const { state: stateA } = state.applyTransaction(transactionA)
      commandB(stateA, (transactionB: Transaction) => {
        transactionB.setMeta('appendedTransaction', transactionA)
        if (dispatch) {
          dispatch(transactionA)
          dispatch(transactionB)
        }
      })
    })
  }