Excellente news, Chrome supporte maintenant nativement les modules ES6. Enfin!

Exemple:

index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Test module ES6</title>
</head>
<body>
  <p>2+3 = <span class="result"></span></p>

  <script type="module">
    import { add } from './common.js'; 
    (function () { 
      document.querySelector('.result').innerText = add(2, 3); 
      console.log(add(2, 3));
    }());
  </script>
  
</body>
</html>

common.js

console.log('common.js');
export function add (a, b) {
    return a + b;
}