Default Imports

You can only default export one thing so it will likely be the class you are defining if you are defining a class in your file

Now in a new file we can import your exported items paying attention to your file paths in the import statements

import User from '/user.js'

this alone will throw an error, in your HTML where you source your javascript files you need to change the script tag to use ES6 modules:

<script src="main.js"></script>

<script type="module" src="main.js"></script>

a tip for the module import <script> tag was the defer keyword. Child issue: #6

so now in a *.js file that does not have the User class declared in it, i can make and use the User class:

const user = new User('Bryan Jenks', 999)
console.log('user')

Result:

User {name: "Bryan Jenks", age: 999} age: 999 name: "Bryan Jenks" proto: Object