reducer in redux performs a minus one operation
export default (state = initialState, action) => {
const {total} = state
switch(action.type){
case ActionTypes.ADD:
//
return {...state, total: total + 1}
case ActionTypes.SUBTRACT:
//
return {...state, total: total - 1}
default:
return state
}
} what is the difference between return {.state, total: total-1} and return state returned by default? what is the role of
.state
because state cannot be modified directly, .state is a copy. {.state, total: total-1} this allows you to modify only the total field in state without affecting other fields in state.
Note state.total = state.total-1; this direct assignment is not allowed by redux, so use the extension operator .
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