blob: 471bd1fb90700db4152835f0df032e70f94c7c6e (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
|
---
title: Headers.has()
slug: Web/API/Headers/has
translation_of: Web/API/Headers/has
---
<div>{{APIRef("Fetch")}}</div>
<p>{{domxref("Headers")}} 接口的 <strong><code>has()</code></strong>方法返回一个布尔值来声明一个 <code>Headers</code>对象 是否包含特定的头信息.</p>
<p>考虑到安全因素, 一些头信息只能被user agent来管理. 这些头信息包括{{Glossary("Forbidden_header_name", "forbidden header names", 1)}} 和{{Glossary("Forbidden_response_header_name", "forbidden response header names", 1)}}.</p>
<h2 id="Syntax">Syntax</h2>
<pre class="brush: js">myHeaders.has(name);</pre>
<h3 id="Parameters">Parameters</h3>
<dl>
<dt><em>name</em></dt>
<dd>你要测试的HTTP头字段的名称。如果给出的名称不在HTTP头中，将爬出异常{{jsxref("TypeError")}}。</dd>
</dl>
<h3 id="Returns">Returns</h3>
<p>A {{domxref("Boolean")}}.</p>
<h2 id="Example">Example</h2>
<p>创建一个空的Headers对象是简单的:</p>
<pre class="brush: js">var myHeaders = new Headers(); // Currently empty</pre>
<p>你可以使用{{domxref("Headers.append")}}来向myHeaders添加一个头信息, 然后使用 <code>has()方法来测试是否添加成功</code>:</p>
<pre class="brush: js">myHeaders.append('Content-Type', 'image/jpeg');
myHeaders.has('Content-Type'); // Returns true
myHeaders.has('Accept-Encoding'); // Returns false
</pre>
<h2 id="Specifications">Specifications</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('Fetch','#dom-headers-has','has()')}}</td>
<td>{{Spec2('Fetch')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility">Browser compatibility</h2>
<p>{{ CompatibilityTable() }}</p>
<div id="compat-desktop">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Chrome</th>
<th>Edge</th>
<th>Firefox (Gecko)</th>
<th>Internet Explorer</th>
<th>Opera</th>
<th>Safari (WebKit)</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{ CompatChrome(42) }}<br>
{{ CompatChrome(41) }} behind pref<br>
</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{ CompatGeckoDesktop(39)}}<br>
34 behind pref</td>
<td>{{ CompatNo }}</td>
<td>
<p>29<br>
28 behind pref</p>
</td>
<td>{{ CompatNo }}</td>
</tr>
</tbody>
</table>
</div>
<div id="compat-mobile">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Android</th>
<th>Edge</th>
<th>Firefox Mobile (Gecko)</th>
<th>Firefox OS (Gecko)</th>
<th>IE Phone</th>
<th>Opera Mobile</th>
<th>Safari Mobile</th>
<th>Chrome for Android</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{ CompatNo }}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{ CompatNo }}</td>
<td>{{ CompatNo }}</td>
<td>{{ CompatNo }}</td>
<td>{{ CompatNo }}</td>
<td>{{ CompatNo }}</td>
<td>{{ CompatNo }}</td>
</tr>
</tbody>
</table>
</div>
<h2 id="See_also">See also</h2>
<ul>
<li><a href="/en-US/docs/Web/API/ServiceWorker_API">ServiceWorker API</a></li>
<li><a href="/en-US/docs/Web/HTTP/Access_control_CORS">HTTP access control (CORS)</a></li>
<li><a href="/en-US/docs/Web/HTTP">HTTP</a></li>
</ul>
|
