服务工作者无法缓存起始url

我把我的应用程序的PWA版本放在 https://www.example.com/app 文件夹。我尝试过使用以下url格式缓存起始页(在 文件\u到\u缓存 )但都不管用

"/"
"/app"
"/app/"
"/app/index.php"
"app"
"app/index.php"
"./"
"./app"

软件js:

const CACHE_NAME = 'static-cache-v1.2';
const DATA_CACHE_NAME = 'data-cache';

//Those tries and errors go here one by one
const FILES_TO_CACHE = [
    "/" 
];

self.addEventListener('install', (evt) => {
    console.log('[ServiceWorker] Install');
    evt.waitUntil(
        caches.open(CACHE_NAME).then((cache) => {
            console.log('[ServiceWorker] Pre-caching offline page');
            return cache.addAll(FILES_TO_CACHE);
        }).then(self.skipWaiting())
    );


});

self.addEventListener('activate', (evt) => {
    console.log('[ServiceWorker] Activate');

    evt.waitUntil(
        caches.keys().then((keyList) => {
            return Promise.all(keyList.map((key) => {
                if (key !== CACHE_NAME) {
                    console.log('[ServiceWorker] Removing old cache', key);
                    return caches.delete(key);
                }
            }));
        })
    );

    self.clients.claim();
});

self.addEventListener('fetch', (evt) => {
console.log('[ServiceWorker] Fetch', evt.request.url);
    evt.respondWith(

        caches.open(CACHE_NAME).then(cache => {
            return cache.match(evt.request).then(cacheResponse => cacheResponse || fetch(evt.request).then(networkResponse => {
                cache.put(evt.request, networkResponse.clone());
                return networkResponse;
            }));

        }))
});

谷歌chrome灯塔说:

脱机时start_url不响应200

<base href="https://www.example.com/app/">

这是我用来注册服务人员的代码 https://www.example.com/app/index.php 并在控制台中接收成功消息:

<script>
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('sw.js', {scope: '/app/'})
  .then((reg) => {
    console.log("Web workers work");
  }).catch((error) => {
    // registration failed
    console.log('Registration failed with ' + error);
  });
}  else{
  console.log("No sw available");
  }

</script>