"Is assigned a value but never used" Redux 减速器中的警告

Question

这是我的代码

import * as actionTypes from '../actions/actionTypes';



const counterReducer = (state = 0, action) => {
let newState;

switch (action.type) {
    case actionTypes.INCREASE_COUNTER:
        return (newState = state + action.payload);
    case actionTypes.DECREASE_COUNTER:
        return (newState = state - action.payload);
    case actionTypes.INCREASE_BY_TWO_COUNTER:
        return (newState = state + action.payload);
    default:
        return state;
 }
}
export default counterReducer;

但我的终端显示 'newState' 已分配一个值但从未使用过。我错过了什么？

Answer 1

您不需要 newState 变量，它在您使用它的方式中毫无用处。没有它你可以得到相同的结果。 return 语句将 return 结果并结束执行而不需要使用变量。

import * as actionTypes from '../actions/actionTypes';



const counterReducer = (state = 0, action) => {
switch (action.type) {
    case actionTypes.INCREASE_COUNTER:
        return state + action.payload;
    case actionTypes.DECREASE_COUNTER:
        return state - action.payload;
    case actionTypes.INCREASE_BY_TWO_COUNTER:
        return state + action.payload;
    default:
        return state;
 }
}
export default counterReducer;

"Is assigned a value but never used" Redux 减速器中的警告

"Is assigned a value but never used" warning in Redux reducer

javascript

eslint

redux