title: Array list in Redux state
body: <p>This is a question about state in Redux js. I have an array list in the state:</p>
  
  <pre><code>{
    list: list
  }
  </code></pre>
  
  <p>According to Redux document, I should not modify the state in the reducer. I want to append a new item to the list. Should I clone the list, or simply append the new item to the list:</p>
  
  <pre><code>let newList = state.list;
  newList.push(newItem);
  return {
    list: newList
  }
  </code></pre>
  
  <p>The above code actually modify the original state, because the newList is the same list as "state.list". Is this an OK practice, or should I use immutableJS to clone the list?</p>