Handling Dynamic Action Types in createReducer

Demonstrate the use of custom action type strings, dynamically creating action handlers inside the createReducer.
import { createReducer } from '@reduxjs/toolkit';

// Custom function to generate action types dynamically
const generateActionType = (base, payload) => `${base}/${payload.toUpperCase()}`;

// Dynamic action creators
const dynamicActionCreator = (baseType, payload) => ({
  type: generateActionType(baseType, payload),

// Define initial state
const initialState = {};

// Define dynamic reducer
const dynamicReducer = createReducer(initialState, (builder) => {
  // We use a placeholder action to dynamically add handlers
  builder.addDefaultCase((state, action) => {
    // Check if the action type matches the dynamic pattern
    if (action.type.startsWith('DYNAMIC/')) {
      // Extract the dynamic part from the action type
      const dynamicPart = action.type.split('/')[1];
      // Apply the corresponding dynamic logic (example: increment number)
      state[dynamicPart] = (state[dynamicPart] || 0) + action.payload;

// Export reducer
export default dynamicReducer;

// Usage:
// dispatch(dynamicActionCreator('DYNAMIC', 'increment', 5));
This code snippet illustrates how to create a dynamic reducer using Redux Toolkit's createReducer function. It generates action types dynamically based on a base type and a payload, and uses a default case to handle these dynamic actions. The dynamicActionCreator is a utility to create an action with the dynamically generated type and payload. Then in the dynamicReducer, any action type that starts with 'DYNAMIC/' will be handled and dynamicPart is used to access or update the state based on action type.