title: the spread operator in Redux reducer
body: <p>I am trying to understand what does spread operator do in Redux state? </p>
  
  <p>I went through this question <a href="https://stackoverflow.com/questions/40690820/purpose-of-the-spread-syntax-in-react-redux-reducers">Purpose of the Spread syntax in React-Redux Reducers</a> but wasn't convince with Answer for some reason. </p>
  
  <p>Can someone please explain me in very simple terms why do we do something like this </p>
  
  <pre><code>  case WHATEVER:
        return {
          ...state,
          DateSucess: action.payload,
  </code></pre>
  
  <p>Instead of just </p>
  
  <pre><code> case WHATEVER
    return {
     DataSucess: action.payload
  </code></pre>