export default class and import not working

Question

I am trying to perform the default export of a class in Node.js, but when I try to compile the main.js file a type error is returned:

Syntaxerror: Unexpected Identifier
at new Script (vm.js:84:7)
creatat eScript (vm.js:264:10)
At object.runInThisContext (vm.js:312:10)
At module. _Compile (Internal/modules/cjs/Loader.js:694:28)
At object.Module. _Extensions.. js (Internal/modules/cjs/Loader.js:745:10)
At module.load (Internal/modules/cjs/Loader.js:626:32)
at tryModuleLoad (Internal/modules/cjs/Loader.js:566:12)
At function.Module. _load (Internal/modules/cjs/Loader.js:558:3)
At function.Module.runMain (Internal/modules/cjs/Loader.js:797:12)
at executeUserCode (Internal/bootstrap/Node.js:526:15)

Can anyone tell me why this happens?

//book.js
export default class Book {
  constructor(title, author) {
    this._title = title;
    this._author = author;
  }
  get title() {
    return this._title;
  }
  set title(title) {
    this._title = title;
  }
  get author() {
    return this._author;
  }
  set author(author) {
    this._author = author;
  }
  printDescription() {
    console.log(`The book ${this._title} was written by ${this._author} `);
  }
}

//main.js
import Book from "./book.js";

const Book01 = new Book("O nome do vento", "Patrick Rothffus");

Book01.printDescription();

Answer 1

In the case of an experimental use there are two ways to do import and export.

The first way is to create a file package.json in the current folder, and then just put into this same file {"type":"module"}. To run the file .js just put:

$ node --experimental-modules index.js 

in place of index.js put the name of the file you want to run.

---

The second way is in the files you will run to exchange the import code from

import Book from "./book.js";

for

import Book from "./book.mjs";

and change extensions of .js for .mjs, and then execute:

$ node --experimental-modules index.mjs

in place of index.mjs put the name of the file you want to run.

---

In the case of non-experimental use:

//book.js
class Book {
  constructor(title, author) {
    this._title = title;
    this._author = author;
  }
  get title() {
    return this._title;
  }
  set title(title) {
    this._title = title;
  }
  get author() {
    return this._author;
  }
  set author(author) {
    this._author = author;
  }
  printDescription() {
    console.log(`The book ${this._title} was written by ${this._author} `);
  }

module.exports = Book;

---

//main.js
const Book = require("./book.js")

const Book01 = new Book("O nome do vento", "Patrick Rothffus");

Book01.printDescription();

---

Bibliography:

https://thecodebarbarian.com/nodejs-12-imports

https://nodejs.org/api/esm.html#esm_code_package_json_code_code_type_code_field

How to export a Node class?