Patterns for deriving state gist7

code.js

    function timeRangeReducer(state,action){
      let days = state.days;
      if (action.type === actionTypes.SET_DAYS){
        days === action.payload;
      }  
      return {
        days,
        formatted: days > 14? `${Math.floor(days / 7)} weeks`:days>1?`${days} days`:'1 day' 
      }
    }