为什么在不能在TypeScript项目ts-node执行.ts文件？

Question

为什么在不能在TypeScript项目执行.ts文件？

我想要封装一个类，并且使用ts-node执行：

src/index.ts

class Animal {
  readonly age: number = 0
  readonly name: string | undefined = undefined

  constructor(age: number, name: string) {
    this.age = age 
    this.name = name
  }
}

export class Person extends Animal {

  readonly height: number 
  constructor(age: number, name: string, height: number) {
    super(age, name)
    this.height = height
  }
}

test/testPerson.ts

import { Person } from '../src/index';


const p = new Person(25, 'John', 177)

console.log(p)

export default {}

我运行ts-node 执行 测试文件报错：不识别.ts后缀的文件：

$ ts-node test/personTest.ts 
TypeError: Unknown file extension ".ts" for /Users/user/Desktop/Test/Test-demos/nodejs-test-demos/nodejs-demo-04-npmpackage/test/personTest.ts
    at Object.getFileProtocolModuleFormat [as file:] (node:internal/modules/esm/get_format:160:9)
    at defaultGetFormat (node:internal/modules/esm/get_format:203:36)
    at defaultLoad (node:internal/modules/esm/load:143:22)
    at async ModuleLoader.load (node:internal/modules/esm/loader:403:7)
    at async ModuleLoader.moduleProvider (node:internal/modules/esm/loader:285:45)
    at async link (node:internal/modules/esm/module_job:78:21) {
  code: 'ERR_UNKNOWN_FILE_EXTENSION'
}

我按照网上说的，找到package.json 删除：
"type": "module",

但是又会报其他错误：

import { Person } from '../src/index';
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at internalCompileFunction (node:internal/vm:128:18)
    at wrapSafe (node:internal/modules/cjs/loader:1280:20)
    at Module._compile (node:internal/modules/cjs/loader:1332:27)
    at Module.m._compile (/Users/user/Library/pnpm/global/5/.pnpm/ts-node@10.9.2_@types+node@20.12.13_typescript@5.4.5/node_modules/ts-node/src/index.ts:1618:23)
    at Module._extensions..js (node:internal/modules/cjs/loader:1427:10)
    at Object.require.extensions.<computed> [as .ts] (/Users/markleo/Library/pnpm/global/5/.pnpm/ts-node@10.9.2_@types+node@20.12.13_typescript@5.4.5/node_modules/ts-node/src/index.ts:1621:12)
    at Module.load (node:internal/modules/cjs/loader:1206:32)
    at Function.Module._load (node:internal/modules/cjs/loader:1022:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:135:12)
    at phase4 (/Users/user/Library/pnpm/global/5/.pnpm/ts-node@10.9.2_@types+node@20.12.13_typescript@5.4.5/node_modules/ts-node/src/bin.ts:649:14)

请问:

1、package.json内"type": "module",的作用是什么呢？
2、我想要到时候打包上传npmjs.org，这个配置"type": "module",会不会有影响呢？
3、SyntaxError: Cannot use import statement outside a module 这个错误如何解决呢？

Answer 1

在 tsconfig.json 中添加：

{
  "compilerOptions": {
    "esModuleInterop": true,
  }
}

运行：ts-node-esm script.ts