加载gltf文件后报错

[cyl0430]

使用 GLTFLoader 加载gltf文件后，报错
`
const gltfLoader = new GLTFLoader(); gltfLoader.load('https://threejsfundamentals.org/threejs/resources/models/cartoon_lowpoly_small_city_free_pack/scene.gltf', (gltf) => {
const root = gltf.scene;
scene.add(root);

}, (e) => {
console.log('loading')
});
`

报错提示为：XMLHttpRequest is not a constructor