阅读 6425

使用 Typescript 踩 react-redux 的坑

背景

最近在看antd源码,也在自学一些typescript的语法以及使用,然后准备带在学校的师弟做一个音乐播放器作为typescript的练习踩踩坑;

然后竟然没想到在项目刚开始就深陷大坑--搭建react-redux项目流程,一下内容就是记录我是怎样从这个深坑中爬出来的过程。

开始?根本开始不起来

从项目创建之后就掉坑里了。。。

创建项目

创建项目的流程很简单,可有参考我之前写的这篇文章

从mapStateToProps&mapDispatchToProps开始爬坑

刚开始还不是很熟悉typescript,所以我最开始的reducer, action, constant,文件都是以.js结尾,只有组件的代码是以.tsx结尾的,然后就开始按照流程,将store中的state进行mapStateToProps以及actions进行mapDispatchToProps,谁想到这竟然是噩梦的开始,最开始我是这样写的代码:

  import { bindActionCreators } from 'redux';
  function mapStateToProps(state: {}) {
    return {
      player: state.PlayerStore,
    };
  }

  function mapDispatchToProps(dispatch: Function) {
    return {
      playerActions: bindActionCreators(actions, dispatch)
    };
  }复制代码

然后就开始报错了。。。

1
1

几经折腾之后我又将代码改成了这样,才得以过关

  import { bindActionCreators, Dispatch } from 'redux';
  function mapStateToProps(state: { PlayerStore: object }) {
    return {
      player: state.PlayerStore,
    };
  }

  function mapDispatchToProps(dispatch: Dispatch<{}>) {
    return {
      playerActions: bindActionCreators<{}>(actions, dispatch)
    };
  }复制代码

爬坑react组件断言类型

  interface PlayerPropsClass {
    player: PlayerStateTypes;
    playerActions: actions.PlayerActionsTypes;
  }
  class Player extends React.Component<PlayerPropsClass, {}> {
    constructor(props: object) {
      super(props as PlayerPropsClass);
      this.state = {};
    }

    addOne = (num: number) => this.props.playerActions.count(num);

    subtractOne = (num: number) => this.props.playerActions.subtract(num);

    render() {
      const { countNumber } = this.props.player.toJS();
      return (
        <div className="player">
          <span>{countNumber}</span>
          <button onClick={() => this.addOne(countNumber as number)}>点击+1</button>
          <button onClick={() => this.subtractOne(countNumber as number)}>点击-1</button>
        </div>
      );
    }
  }

  export default connect(mapStateToProps, mapDispatchToProps)(Player as any);复制代码

这里的(Player as any)报错提示

  [tslint] Type declaration of 'any' loses type-safety. Consider replacing it with a more precise type, the empty type ('{}'), or suppress this occurrence. (no-any)复制代码

然后我改成

  export default connect(mapStateToProps, mapDispatchToProps)(Player as {});复制代码

仍然报错

  [ts]
  类型“{}”的参数不能赋给类型“ComponentType<{ player: object; } & { playerActions: {}; }>”的参数。
  不能将类型“{}”分配给类型“StatelessComponent<{ player: object; } & { playerActions: {}; }>”。
  类型“{}”提供的内容与签名“(props: { player: object; } & { playerActions: {}; } & { children?: ReactNode; }, context?: any): ReactElement<any> | null”不匹配。复制代码

哇心态爆炸,都不知道怎么写这个断言。。。然后我想起了antd的一个例子,写的是React.ReactElement,然后偶然间在网上找到了说的是在node_modules中有一个@type文件夹就是typescript对于node包中的相应的类型匹配,于是我就按照这个路径node_modules/@types/react/index.d.ts,终于找到了React.ComponentType<T>,这个文件里面还有很多的类型,想要了解的可以自己去看看

  export default connect(mapStateToProps, mapDispatchToProps)(Player as React.ComponentType<PlayerPropsClass>);复制代码

爬坑action和reducer

有了以上的经验,再加上在这里看了一些代码,我决定把actions和reducer也改为ts结尾的文件;

  • src/reducers/index.ts

      import { combineReducers, createStore } from 'redux';
      import PlayerStore from '../containers/Player/reducer';
    
      // 这个是用来使用到mapStateToProps函数的地方给state进行类型检测的
      export interface AppStoreType {
        PlayerStore: object;
      }
    
      const rootReducer = combineReducers({
        PlayerStore,
      });
    
      export default () => {
        return createStore(rootReducer);
      };复制代码
  • containers/Demo/reducer.ts

      import * as PlayerTypes from './constant';
      import { fromJS } from 'immutable';
      // 由于使用到immutable,state上面就会使用到immutable的函数,所以需要将其也做成类型检测
      import { ImmutableFuncType } from '../../constant';
    
      interface ActionType {
        type: string;
        countNumber?: number;
      }
    
      interface StoreType {
        countNumber: number;
      }
      // 把当前容器的state组,然后抛出提供使用
      export type PlayerStateTypes = StoreType & ImmutableFuncType;
    
      const PlayerStore: PlayerStateTypes = fromJS({
        countNumber: 0,
      });
    
      export default (state = PlayerStore, action: ActionType) => {
        switch (action.type) {
          case PlayerTypes.COUNT:
            return state.update('countNumber', () => fromJS(action.countNumber));
          default:
            return state;
        }
      };复制代码
  • containers/Demo/action.ts

      import * as PlayerTypes from './constant';
    
      export const count = (num: number) => ({
        type: PlayerTypes.COUNT,
        countNumber: num + 1,
      });
    
      export const subtract = (num: number) => ({
        type: PlayerTypes.COUNT,
        countNumber: num - 1,
      });
      // 抛出actions函数的类型以供mapDispatchToProps使用
      export interface PlayerActionsTypes {
        count: Function;
        subtract: Function;
      }复制代码
  • containers/Demo/index.tsx

      import * as React from 'react';
      import './style.css';
      import { connect } from 'react-redux';
      import { bindActionCreators, Dispatch } from 'redux';
      import * as actions from './action';
      import { PlayerStateTypes } from './reducer';
      import { AppStoreType } from '../../reducers';
    
      interface PlayerPropsClass {
        player: PlayerStateTypes;
        playerActions: actions.PlayerActionsTypes;
      }
    
      function mapStateToProps(state: AppStoreType) {
        return {
          player: state.PlayerStore,
        };
      }
    
      function mapDispatchToProps(dispatch: Dispatch<{}>) {
        return {
          playerActions: bindActionCreators<{}>(actions, dispatch)
        };
      }
    
      class Player extends React.Component<PlayerPropsClass, {}> {
        constructor(props: object) {
          super(props as PlayerPropsClass);
          this.state = {};
        }
    
        addOne = (num: number) => this.props.playerActions.count(num);
    
        subtractOne = (num: number) => this.props.playerActions.subtract(num);
    
        render() {
          const { countNumber } = this.props.player.toJS();
          return (
            <div className="player">
              <span>{countNumber}</span>
              <button onClick={() => this.addOne(countNumber as number)}>点击+1</button>
              <button onClick={() => this.subtractOne(countNumber as number)}>点击-1</button>
            </div>
          );
        }
      }
    
      export default connect(mapStateToProps, mapDispatchToProps)(Player as React.ComponentType<PlayerPropsClass>);复制代码

结尾

通过这个小练习还真的是感受到了typescript的好处,那就是在编译时就报错,而且能够知道报错原因,不需要在编译完成以后再去进行错误点的查找,确实节省了很多时间,尤其是对于JavaScript代码的undefined和null的处理很友好。。总之,感觉写起来很流畅啊。啊哈哈哈哈~~~