转换为Typescript后，模块没有默认导出 [英] Module has not default export after converting to Typescript

问题描述

我已将JavaScript代码转换为Typescript并收到错误

I have converted the JavaScript code to Typescript and getting the error

模块没有默认导出

Module has no default export

我尝试使用花括号导入，并使用module.exports导出，但是没有一个起作用.

I have tried importing using the curly braces and exporting using module.exports but none of them worked.

contactController.ts

const contacts: String[] = [];

// Handle index actions
exports.index = (req: any, res: any) => {
    res.json({
        data: contacts,
        message: "Contacts retrieved successfully",
        status: "success"
    });
};

// Handle create contact actions
exports.new = (req: any, res: any) => {

     // save the contact and check for errors
    contacts.push("Pyramids");

    res.json({
            data: contact,
            message: "New contact created!"
        });
};

api-route.ts

import contactController from "./contactController";

在api-routes.ts中，当我尝试导入contactController模块时，它将引发错误

In the api-routes.ts, when I am trying to import the contactController module it is throwing the error

模块没有默认导出

Module has no default export

如何导入而不会出现错误?我尝试使用从"./contactController"导入"{contactController}"，但是效果不佳.

How can I import without the error? I have tried using "import {contactController} from "./contactController" but that did not work as well.

推荐答案

文档(请参见导出"和导入"部分): 以这种方式导入模块时:

When you import a module this way:

// <some_file>.ts
import <whatever_name_I_want> from "<path_to_my_awesome_module>";

< my_awesome_module> .ts 需要具有默认导出.例如，可以通过以下方式完成此操作:

<my_awesome_module>.ts needs to have a default export. For example, this can be done this way:

// <my_awesome_module>.ts
export default foo = () => { // notice the 'default' keyword
  // ...
};

export bar = () => {
  // ...
};

使用上面的代码，< whatever_name_I_want> 将是 foo 方法(一个模块只能具有 1 默认导出).为了同时导入 bar 方法，您将必须单独导入它:

With the code above, <whatever_name_I_want> will be the foo method (a module can only have 1 default export). In order to import the bar method as well, you will have to import it seperately:

// <some_file>.ts
import <whatever_name_I_want>, { bar } from "<path_to_my_awesome_module>";

---

但是根据您要执行的操作，可能不需要使用默认导出.您可以使用 export 关键字简单地导出所有方法，如下所示:

---

But according to what you're trying to do, there is probably no need to use a default export. You could simply export all your methods with the export keyword, like this:

// contactController.ts
export index = (req: any, res: any) => { // no need for a default export
  // ...
};

export create = (req: any, res: any) => {
  // ...
};

并将它们都导入到方括号中:

and import them both either in brackets:

// api-routes.ts
import { index, create } from "./contactController";

// Usage
index(...);
create(...);

或全局变量中:

// api-routes.ts
import * as contactController from "./contactController";

// Usage
contactController.index(...);
contactController.create(...);

PS:我在 create 中重命名了您的 new 方法，因为"new"已经是一个JavaScript关键字.

PS: I renamed your new method in create because "new" is already a JavaScript keyword.

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