Typescript: Cannot use import statement outside a module

Question

I have a .ts file in node js (latest version of node.js for 07.10.19) app with importing node-module without default export. I use this construction: import { Class } from 'abc'; When i run the code, i have this error: Cannot use import statement outside a module.

In the network i see many solutions for this problem (for .js), but it not helps to me, maybe because i have typescript file. Here's my code:

import { Class } from 'abc';
module.exports = { ...
    execute(a : Class ,args : Array<string>){ ...

Here's my tsconfig.json:

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",

    "strict": true
  }
}

Answer 1

Adding "type": "module" to package.json will tell Node you are using ES2015 modules, which should get rid of the error, but then you will need to tell Typescript to generate this type of module by setting "module": "es2015" instead of "commonjs" in tsconfig.json.

This however causes a problem with the current code because although you are using an ES6 import {} statement you are exporting using the commonJS module.exports = {} syntax, and Node’s ES module loader will have an issue with it. There are two ways to deal with it:

1. Keep the module.exports but tell Node to interpret this file as commonJS by giving it a .cjs extension.
2. Change the export statement to ES2015 syntax: export function execute(…)..

The first option could get a bit tricky because the compiler will output .js files and you’d have to change it to .cjs all the time (as far as I know). With the second option you should be able to run the file with Node (including the --experimental-modules flag for versions < 13.8).

If you absolutely need to use commonJS, perhaps it is better to install the type definitions for Node: @types/node and change the import to commonJS format: require('abc') and keep the rest of the settings as they are (though you can add “type”: “commonjs” to package.json to be explicit).