HELP on Never Mutate State

JavaScript
1

**I’ve assigned to state2 the state in order to avoid mutating the state array, and therefore making a _push _ on the state2 which is an array. But nothing worked. what to do Please??? state2 is supposed to be a copy of state **

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) => {
  let state2 = todos;
  switch(action.type) {
    case ADD_TO_DO:
      // don't mutate state here or the tests will fail
      {
      state2.push(action.todo);
       return state2;
      }
    default:
      return state;
  }
};

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

const store = Redux.createStore(immutableReducer);

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:62.0) Gecko/20100101 Firefox/62.0.

Link to the challenge:
https://learn.freecodecamp.org/front-end-libraries/redux/never-mutate-state

2

Assigning an array to another variable is still pointing a reference it, so you are actually mutating its state.

Search google on how to make a copy of an array. You can use slice method or map method as well.

You should also assign paratmeter todo to todo here.

3

Hello brother.

You instead of mapping through the array or slicing it you could try using CONCAT in order to place the ACTION.TODO on the last position of the array.

I hope that helps a little bit.

Peace!

4

Thanks @luizmelo001 it’s ok now. I’m actually struggling with the 2nd project on markdown previewer. Please Hey guy, Thanks a lot. It worked! Now how to parse a markdown code to an html? I’ve used the new Remarkable() object, then called the render method with no success. It’s said on the http:localhost:3000 page Remarkable is not derfined . What to do please?

const md = new Remarkable();
...
<div id="preview" className="previewer" dangerouslySetInnerHTML = {{__html: md.render(this.state.markdown)}}/>