insert/update object in array using index when array is empty in redux react

I am working on a react project and using redux for state management.I want to update values in an array using index but initially the array is empty.

How can I do it?

I am doing this:

case Actions.UPDATE:
      return {
        ...state,
        defaultCodeList: state.defaultCodeList.map((code, index) => (index === action.index ? {
          code_sys_id: state.masterName, code_sys_cat_id: state.codeSystem, [`${state.codeSystem}_description`]: action.description,
        } : codeset)),
      };

Initailly defaultCodeList:[] and on pressing of a button I am triggering this action. I want to put the above object on that particular index when the index matches.

Any leads on this?

Answer

Create a new array set the index of the array identical to the action’s index to the object value. This would set all other indexes to undefined. ou then can now set the undefined values in the array to codeset when assigning it to defaultCodeList

case Actions.UPDATE:
    const newDefaultCodeList = [...state.defaultCodeList];
    newDefaultCodeList[action.index] = {
        code_sys_id: state.masterName, code_sys_cat_id: state.codeSystem, [`${state.codeSystem}_description`]: action.description,
    } // this sets the remaining values at other indexes to undefined
    return {
        ...state,
        defaultCodeList: newDefaultCodeList.map((code, index) => (index !== action.index && codeset)),
    };