Never Mutate State - help :)

Tell us what’s happening:
Hello everyone!

The lesson states that every time we return a state, it’s another version of the state rather than a modified state. How do you I see different states? Store.dispatch(addToDo("Learn React)) & console.log(todos) returns the old state without “Learn React” in the array.


Your code so far

const ADD_TO_DO = 'ADD_TO_DO';

// A list of strings representing tasks to do:
const todos = [
  'Go to the store',
  'Clean the house',
  'Cook dinner',
  'Learn to code',

const immutableReducer = (state = todos, action) => {
  switch(action.type) {
    case ADD_TO_DO:
      // don't mutate state here or the tests will fail
      return todos.concat(action.todo)
      return state;

// an example todo argument would be 'Learn React',
const addToDo = (todo) => {
  return {
    type: ADD_TO_DO,

const store = Redux.createStore(immutableReducer);

store.dispatch(addToDo("Learn React"))

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36.

Link to the challenge: