Typescript中使用node-fetch时出现“SyntaxError：Cannot use import statement outside a module”的错误。

Question

正如标题所述，我在创建一个 TypeScript 库的 npm 包时遇到了麻烦。我的问题出现在尝试导入 node-fetch 来执行 fetch 调用时。我创建了这个示例 git仓库来重现我的问题。

我使用了以下命令来达到这个阶段：

npm i --save-dev typescript ts-node jest @types/jest ts-jest
jest --init
npm i node-fetch

我已将 package.json 配置为：

"main": "dist/index.js",
"types": "dist/index.d.ts",
"files": [
  "/dist"
],
"scripts": {
  "test": "jest --coverage",
},

我已经将tsconfig.json配置为：

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es2015",
    "declaration": true,
    "outDir": "./dist"
  },
  "include": ["src/**/*"]
}

我的 jest.config.js 包含:

module.exports = {
  preset: "ts-jest",
  testEnvironment: "node",
  transformIgnorePatterns: ["/node_modules/"],
};

当我运行npm text时，结果如下：

> tslib@0.1.0 test
> jest --coverage

 FAIL  tests/unit/index.test.ts
  ● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /Users/d.tentoni/Documents/uni/tslib/node_modules/node-fetch/src/index.js:9
    import http from 'node:http';
    ^^^^^^

    SyntaxError: Cannot use import statement outside a module

    > 1 | import fetch from "node-fetch";
        | ^
      2 |
      3 | export async function scrape() {
      4 |   const response = await fetch(

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1728:14)
      at Object.<anonymous> (src/scraper.ts:1:1)

有人能给我一些建议吗？我如何在我的Typescript项目中使用node-fetch？

编辑1：使用命令npm i got安装Got后，我得到了相同的错误。

编辑2：添加了jest.config.js文件的内容。

- Daniele Tentoni

Answer 1

你有jest的配置文件吗？你需要指定使用ts-jest，就像jest的第三行所说的那样，jest无法读取非JS语法（只能是Babel），但是看起来你没有babel的配置文件。这意味着Jest试图将TypeScript作为JavaScript运行，显然会抛出一个SyntaxError。

尝试运行 npx ts-jest config:init 或者如果你更喜欢yarn yarn ts-jest config:init

- Pyxel Codes

---

你好@pixel，我的示例存储库中有一个jest.config.ts文件，其中包含“preset:“ts-jest”，testEnvironment:“node””设置，与您的命令放置在创建的jest.config.js文件中相同。当我使用*.js配置运行Jest时，使用“test”:“jest --coverage --config jest.config.js”命令，输出不会改变。 - Daniele Tentoni