CommonJS
app.js
const express = require('express');
const app = express();
...ES Modules
app.js
import express from 'express';
const app = express();
...package.json
{
...
"type": "module"
...
}const express = require('express');
const app = express();
...import express from 'express';
const app = express();
...{
...
"type": "module"
...
}