Addressing nits from service worker PR.

src/components/compress/index.tsx

@@ -156,7 +156,7 @@ async function processSvg(blob: Blob): Promise<HTMLImageElement> {
   return blobToImg(new Blob([newSource], { type: 'image/svg+xml' }));
 }
 
-async function getOldestServiceWorker() {
+async function getMostActiveServiceWorker() {
   const reg = await navigator.serviceWorker.getRegistration();
   if (!reg) return null;
   return reg.active || reg.waiting || reg.installing;
@@ -209,7 +209,7 @@ export default class Compress extends Component<Props, State> {
       .then(async (userInteracted: boolean | undefined) => {
         if (userInteracted) return;
         set('user-interacted', true);
-        const serviceWorker = await getOldestServiceWorker();
+        const serviceWorker = await getMostActiveServiceWorker();
         if (!serviceWorker) return; // Service worker not installing yet.
         serviceWorker.postMessage('cache-all');
       });

src/sw/util.ts

@@ -46,6 +46,12 @@ export function cleanupCache(event: FetchEvent, cacheName: string, keepAssets: s
   }());
 }
 
+function getAssetsWithPrefix(assets: string[], prefixes: string[]) {
+  return assets.filter(
+    asset => prefixes.some(prefix => asset.startsWith(prefix)),
+  );
+}
+
 export async function cacheBasics(cacheName: string, buildAssets: string[]) {
   const toCache = ['/', '/assets/favicon.ico'];
 
@@ -60,9 +66,7 @@ export async function cacheBasics(cacheName: string, buildAssets: string[]) {
     'logo.',
   ];
 
-  const prefixMatches = buildAssets.filter(
-    asset => prefixesToCache.some(prefix => asset.startsWith(prefix)),
-  );
+  const prefixMatches = getAssetsWithPrefix(buildAssets, prefixesToCache);
 
   toCache.push(...prefixMatches);
 
@@ -80,10 +84,7 @@ export async function cacheAdditionalProcessors(cacheName: string, buildAssets:
     'process-',
   ];
 
-  const prefixMatches = buildAssets.filter(
-    asset => prefixesToCache.some(prefix => asset.startsWith(prefix)),
-  );
-
+  const prefixMatches = getAssetsWithPrefix(buildAssets, prefixesToCache);
   const wasm = buildAssets.filter(asset => asset.endsWith('.wasm'));
 
   toCache.push(...prefixMatches, ...wasm);