Basic Reducer Functionality (Dispatching Actions sent from components)

rootReducer.js

// initState defined beforehand in file or wherever and import it

const rootReducer = (state = initState, action) => {
  if (action.type === 'DELETE_POST') {
    let newPosts = state.posts.filter(post => action.id !== post.id);

    return {
      ...state,
      posts: newPosts
    };
  }
  return state;
};