javascript - Redux - Having an issue concatenating new state when an Item is added to an array -

currently having issue reducer function not update questionlist.items array. i'm not sure i'm doing wrong here awesome if point me in right direction :)

below snippet of code i'm having issue with. problem lies add_questions action it not concatenate existing items in array new item. instead, it overwrites existing item in array.

const add_question = 'add_question'; const fetch_questions = 'fetch_questions'; const fetch_questions_success = 'fetch_questions_success'; const fetch_questions_failure = 'fetch_questions_failure';  const initial_state = {    questionslist: {items: [{     id: 2222,     questionstring: 'your name',     rejected: true   }], error:null, loading: false},     newquestion:{question:null, error: null, loading: false},      activequestion:{question:null, error:null, loading: false},      deletedquestion: {question: null, error:null, loading: false}, };  const questionsreducer = (state = initial_state, action) => {   const { payload, type } = action;   switch (type) {   case fetch_questions:       return { ...state, questionslist: {items:[], error: null, loading: true} };      case fetch_questions_success:       return { ...state, questionslist: {items: action.payload, error:null, loading: false} };     case add_question:       /** problem lies here */        return { ...state, questionslist: { items: [...state, payload], error: null, loading: false } }     default: return state   } }  export default questionsreducer; 

i've taken screenshot of redux devtools console better show issue i'm dealing with. taking @ picture below see initial item in items array gets replaced when add_question fires.

you trying spread whole state, not list of questions:

return { ...state, questionslist: { items: [...state, payload], error: null, loading: false } } 

you cannot spread object array. instead, only spread relevant slice of state:

return { ...state, questionslist: { items: [...state.questionslist.items, payload], error: null, loading: false } }