---
title: Early-Data
slug: Web/HTTP/Headers/Early-Data
translation_of: Web/HTTP/Headers/Early-Data
---
<div>{{SeeCompatTable}}{{HTTPSidebar}}</div>

<p><code><strong>Early-Data</strong></code> 头（header）由某个中间者设置来表示请求已在TLS early data 中传送 ，且表示 某个中间者理解 {{HTTPStatus("425", "425 (Too Early)")}} 状态码。<code><strong>Early-Data</strong></code> 头（header）不由请求的发起者设置 (例如，浏览器)。</p>

<table class="properties">
 <tbody>
  <tr>
   <th scope="row">Header type</th>
   <td>{{Glossary("Request header")}}</td>
  </tr>
  <tr>
   <th scope="row">{{Glossary("Forbidden header name")}}</th>
   <td>no</td>
  </tr>
 </tbody>
</table>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">Early-Data: 1
</pre>

<h2 id="示例">示例</h2>

<pre>GET /resource HTTP/1.0
Host: example.com
Early-Data: 1</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Title</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{RFC("8470", "The Early-Data Header Field", "5.1")}}</td>
   <td>Using Early Data in HTTP</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容">浏览器兼容</h2>

<p>{{Compat("http.headers.Early-Data")}}</p>