我是新手，我在 udemy 中学习教程，但出现错误:

 Line 45:9:  Parsing error: Unexpected token, expected "," 
 
  43 |     TodoDataService.deleteTodo(username, id).then(() => 
  44 |       this.setState({ message: `Delete of ${id} successfull` }) 
> 45 |         this.refreshTodo() 
     |         ^ 
  46 |        
  47 |     ); 
  48 |   } 

import Axios from "axios"; 
 
class TodoDataService { 
  retrieveAllTodos(username) { 
    return Axios.get(`http://localhost:8080/users/${username}/todos`); 
  } 
 
  deleteTodo(username, id) { 
    return Axios.delete(`http://localhost:8080/users/${username}/todos/${id}`); 
  } 
 
  updateTodo(username, id) { 
    return Axios.put(`http://localhost:8080/users/${username}/todos/${id}`); 
  } 
} 
 
export default new TodoDataService(); 

请您参考如下方法:

您有语法错误。 TodoDataService.deleteTodo(username, id)返回一个 promise ，然后您正在调用 then 并传递一个闭包。但是，您的闭包在语法上无效，因为它有多行代码，但省略了打开和关闭分支。
你应该有:

TodoDataService.deleteTodo(username, id).then(() => { 
  this.setState({ message: `Delete of ${id} successful` }); 
  this.refreshTodo(); 
}); 

const add = (a, b) => a + b; 
> add(1, 2) 
< 3 

const brokenAdd = (a, b) => { 
  a + b; 
}; 
> brokenAdd(1, 2) 
< undefined