用 responseStatus 属性: const observer = new PerformanceObserver((list) => { list.getEntries().forEach((entry) => { if (entry.responseStatus === 304) { console.log(`${entry.name} was loaded from cache`); } }); }); observer.observe({ type: "resource", buffered: true }); 或者用 transferSize 属性可以用来检查本地缓存有没有命中,如果 transferSize 的值为 0,就表示资源是从缓存加载的,不是从网络加载的