Redux reducer, check if value exists in state array and update state
<p>So I've got an array <code>chosenIds[]</code> which will essentially hold a list of <code>ids (numbers)</code>. But I'm having trouble accessing the state in my reducer to check whether the <code>ID I parsed to my action</code> is in the array.</p>

<pre><code>  const initialState = {
  'shouldReload': false,
  'chosenIds': [],
};

export default function filter(state = initialState, action) {
  switch (action.type) {


 case ADD_TYPE:
      console.log(state.chosenIds, "Returns undefined???!!!");

      // Check if NUMBER parsed is in state
      let i = state.chosenIds.indexOf(action.chosenId);

      //If in state then remove it
      if(i) {
        state.chosenIds.splice(i, 1);
        return {
          ...state.chosenIds,
          ...state.chosenIds
        }
      }
      // If number not in state then add it 
      else {
        state.chosenIds.push(action.chosenId)
        return { ...state.chosenIds, ...state.chosenIds }
      }
</code></pre>

<p>I'm not to sure what's going on...But when I log <code>state.chosenIds</code>, it returns undefined? It doesn't even return the initial empty array <code>[]</code> .</p>

<p>Basically what this function is suppose to do is check to see if the <code>action.chosenId</code> is in the <code>state.chosenIds</code>, If it is, then remove the <code>action.chosenId</code> value, if it's not, then add the <code>action.chosenId</code> to the state.</p>