SyntaxError：无法在 NodeJS Typescript 的模块外使用 import 语句

Question

I am trying to write tests with Jest in my Express Typescript application. In the test files, when I am import functions from another file, I get SyntaxError: Cannot use import statement outside a module . This is my package.json-

{
  "name": "customer-cart-service",
  "version": "1.0.0",
  "description": "",
  "main": "handler.js",
  "type": "module",
  "scripts": {
    "test": "jest --verbose ./tests"
  },
  "dependencies": {
    "cookie-parser": "^1.4.6",
    "express": "^4.17.1",
    "serverless-http": "^2.7.0"
  },
  "devDependencies": {
    "@aws-sdk/client-dynamodb": "^3.209.0",
    "@aws-sdk/lib-dynamodb": "^3.209.0",
    "@types/aws-lambda": "^8.10.108",
    "@types/cookie-parser": "^1.4.3",
    "@types/express": "^4.17.14",
    "@types/jest": "^29.2.4",
    "jest": "^26.6.3",
    "serverless-bundle": "^5.5.0",
    "serverless-dynamodb-local": "^0.2.40",
    "serverless-offline": "^11.2.3",
    "typescript": "^4.8.4"
  }
}

This is my tsconfig.json-

{
  "compilerOptions": {
    "target": "es2016",                                 
    "module": "commonjs",  
    "baseUrl": "./",                  
    "paths": {
      "*": [
        "node_modules/*",
        "src/@types/*"
      ]
    },          
    "outDir": "./dist",
    "removeComments": true,  
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true, 
    "forceConsistentCasingInFileNames": true, 
    "strict": true, 
    "noImplicitAny": true,
    "strictNullChecks": true, 
    "strictFunctionTypes": true,
    "strictBindCallApply": true,
    "strictPropertyInitialization": true,
    "noImplicitThis": true,  
    "alwaysStrict": true, 
    "noImplicitReturns": true,
    "skipLibCheck": true 
  }
}

add.ts-

import { add1 } from "../functions/add"

it('simple test',()=>{
    expect(add1(2,3).toBe(5);
})

add.ts-

export function add1(a:number,b:number) {
    return a+b;
}

Whatever I try, I am unable to resolve this error- SyntaxError: Cannot use import statement outside a module. Adding "type":"module" as shown in many solutions did not work.

Answer 1

This is because your code is being compiled to CommonJS as seen in your tsconfig. Changing the module field to ESNext should fix the issue.

Read more about ES modules here: https://www.typescriptlang.org/docs/handbook/esm-node.html