ink to 3. 协商缓存">​</a></h3><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="31-etag--if-none-match">3.1 ETag / If-None-Match<a href="#31-etag--if-none-match" class="hash-link" aria-label="Direct link to 3.1 ETag / If-None-Match" title="Direct link to 3.1 ETag / If-None-Match">​</a></h4><ul><li>通过唯一标识来验证缓存。</li><li>优先级高于 Last-Modified / If-Modified-Since。</li></ul><p>如果资源请求的响应头里含有 ETag，客户端可以在后续的请求的头�