service-worker - 如何在 Service Worker addAll 中通知哪些文件或资源无法获取

Question

我需要知道如何向客户端发送无法获取的请求：

self.addEventListener('install', async ()=>{
    event.waitUntil(caches.open(CACHE_NAME).then((cache)=>
        cache.addAll(urlsToCache)
    ));
});

我需要在客户端接收它。就像是：

//client.js

var reg=Navigator.serviceWorker.register('sw.js');
Navigator.serviceWorker.onerror=(ev)=>{
    document.getElementById('err1').textContent = ev.data.message;
}

// sw.js
self.addEventListener('install', async (ev)=>{
    event.waitUntil(caches.open(CACHE_NAME).then((cache)=>
        cache.addAll(urlsToCache)
    ).catch((err)=>{
        var client = clients.get(ev.clientId);     // ev does not have clientId
        client.postMessage(err.offendingRequest);  // offendingRequest does not exist
    }));
});