React组件类中的JavaScript对象函数

Question

我在react组件中使用了对象函数，下面是我的代码，我尝试在articleActions对象中创建一个对象函数，但没有得到语法错误。 api 导入工作正常，我获得了正确的数据并存储在此组件状态中:this.state.articles、this.state.authors。

App.js
import React from "react";
import DataApi from "../DataApi";
import data from "../testData";
import ArticleList from "./ArticleList";

const api = new DataApi(data.data);

class App extends React.Component {
    constructor() {
    super();
     this.state = {
       articles: api.getArticles(),
       authors: api.getAuthors()
      };
    }
    articleActions = {
       lookupAuthor: authorId => this.state.authors[authorId]
    };
    render() {
      return (
       <ArticleList
         articles={this.state.articles}
         articleActions={this.articleActions}
       />
   );
}
}

export default App;

第二个文件:ArticleList.js

import React from "react";

import Article from "./Article";

 const ArticleList = props => {
      return (
        <div>
          {Object.values(props.articles).map(article => (
             <Article
               key={article.id}
               article={article}
               actions={props.articleActions}
             />
          ))}
        </div>
       );
      };

 export default ArticleList;

第三个文件:Article.js

import React from "react";

 const Article = props => {
    const { article, actions } = props;
    const author = actions.lookupAuthor(article.authorId);
    return (
      <div>
      <div>{article.title}</div>
      <div>{article.date}</div>
      <div>
          <a href={author.website}>
              {author.firstName} {author.lastName}
          </a>
      </div>
      <div>{article.body}</div>
    </div>
   );
 };

 export default Article;

错误消息是:

SyntaxError: C:/Users/coral/Documents/react-advanced/lib/components/App.js: 
  Unexpected token (16:17)
  14 |     };
  15 |   }
> 16 |   articleActions = {
     |                  ^
  17 |     lookupAuthor: authorId => this.state.authors[authorId]
  18 |   };

lookupAuthor应该是一个参数为authorId的函数，并获取作者对象的返回值。 this.state.authors 是作者对象的数组。每个对象以authorId为键，以author对象为值。我不确定在 js 对象内声明函数时出现什么错误。希望有人能帮忙

Answer 1

这应该是方法:

articleActions = () => ({
  lookupAuthor: authorId => this.state.authors[authorId]
});