node-fetch 3.0.0 和 jest 给出 SyntaxError Cannot use import statements Outside a mo

在使用 node-fetch 3.0.0 和 jest 进行开发时，有时候会遇到一个常见的错误：SyntaxError: Cannot use import statements Outside a module。这个错误通常发生在尝试在浏览器环境之外使用 import 语句时。本文将解释这个错误的原因，并提供一个案例代码来说明问题。

javascript
// file1.js
import fetch from 'node-fetch';
const fetchData = async () => {
  const response = await fetch('https://api.example.com/data');
  const data = await response.json();
  return data;
};
export default fetchData;

javascript
// file2.js
import fetchData from './file1.js';
const processData = async () => {
  const data = await fetchData();
  // process the data
};
processData();

javascript
// file1.js
const fetch = require('node-fetch');
const fetchData = async () => {
  const response = await fetch('https://api.example.com/data');
  const data = await response.json();
  return data;
};
module.exports = fetchData;

javascript
// file2.js
const fetchData = require('./file1.js');
const processData = async () => {
  const data = await fetchData();
  // process the data
};
processData();