Cannot use import statement outside a module javascript error

Question

this is my code :

import * as THREE from 'three.js/build/three.module.js';
import { GLTFLoader } from 'three.js/examples/jsm/loaders/GLTFLoader.js';

but when I run console error :

Uncaught SyntaxError: Cannot use import statement outside a module (at app.js:1:1)