I'm trying to create a theme app extension for shopify, i'm currently working with an app block, i need to import an npm package, let's say moment.js so i did the following

import moment from "moment";

but i got the error

Uncaught SyntaxError: Cannot use import statement outside a module

so i tried with the require syntax

const moment = require("moment");

but the result is

Uncaught ReferenceError: require is not defined

this is the block template

<button id="random-button">
  random label
</button>

{% schema %}
{
    "name": "Random App Block",
    "target": "section",
    "javascript": "app.js",
    "stylesheet": "style.css",
    "settings":[]
}
{% endschema %}

What am i missing? I've just created the app with the Shopify CLI and added the extension, what's the correct way to import an npm package in an app block?