react中reduce基本使用

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import React ,{useReducer}from 'react'; import './App.css';     const App =() =>{     const reduce =(state,action)=>{     const actionFn = {      add:function(){        return {          ...state,          count:state.count+1        }      }    }       return actionFn[action.type]();     }     const [state,dispatch] = useReducer(reduce,{count:0})     const addCount = () =>{    dispatch({type:'add'})  }     return (      <div>         <div>{state.count}</div>         <button onClick={addCount}>+1</button>      </div>     ); }   export default App;