头
接口在
抓取 API
allows you to perform various actions on
HTTP request and response headers
. These actions include retrieving, setting, adding to, and removing headers from the list of the request's headers.
A
头
object has an associated header list, which is initially empty and consists of zero or more name and value pairs.
You can add to this using methods like
append()
(见
范例
)。
In all methods of this interface, header names are matched by case-insensitive byte sequence.
For security reasons, some headers can only be controlled by the user agent. These headers include the forbidden header names and forbidden response header names .
A Headers object also has an associated guard, which takes a value of
immutable
,
request
,
request-no-cors
,
response
，或
none
. This affects whether the
set()
,
delete()
，和
append()
methods will mutate the header. For more information see
Guard
.
You can retrieve a
头
object via the
Request.headers
and
Response.headers
properties, and create a new
头
对象使用
Headers.Headers()
构造函数。
An object implementing
头
can directly be used in a
for...of
structure, instead of
entries()
:
for (var p of myHeaders)
相当于
for (var p of myHeaders.entries())
.
注意 : you can find more out about the available headers by reading our HTTP headers reference.
Headers()
头
对象。
Headers.append()
头
object, or adds the header if it does not already exist.
Headers.delete()
头
对象。
Headers.entries()
iterator
allowing to go through all key/value pairs contained in this object.
Headers.forEach()
Executes a provided function once for each array element.
Headers.get()
ByteString
sequence of all the values of a header within a
头
object with a given name.
Headers.has()
头
object contains a certain header.
Headers.keys()
iterator
allowing you to go through all keys of the key/value pairs contained in this object.
Headers.set()
头
object, or adds the header if it does not already exist.
Headers.values()
iterator
allowing you to go through all values of the key/value pairs contained in this object.
注意
: To be clear, the difference between
Headers.set()
and
Headers.append()
is that if the specified header does already exist and does accept multiple values,
Headers.set()
will overwrite the existing value with the new one, whereas
Headers.append()
will append the new value onto the end of the set of values. See their dedicated pages for example code.
注意
: All of the Headers methods will throw a
TypeError
if you try to pass in a reference to a name that isn't a
valid HTTP Header name
. The mutation operations will throw a
TypeError
if the header has an immutable
Guard
. In any other failure case they fail silently.
注意 : When Header values are iterated over, they are automatically sorted in lexicographical order, and values from duplicate header names are combined.
Headers.getAll()
头
object with a given name; this method has now been deleted from the spec, and
Headers.get()
now returns all values of a given name instead of just the first one.
In the following snippet, we create a new header using the
Headers()
constructor, add a new header to it using
append()
, then return that header value using
get()
:
var myHeaders = new Headers();
myHeaders.append('Content-Type', 'text/xml');
myHeaders.get('Content-Type') // should return 'text/xml'
The same can be achieved by passing an array of arrays or an object literal to the constructor:
var myHeaders = new Headers({
'Content-Type': 'text/xml'
});
// or, using an array of arrays:
myHeaders = new Headers([
['Content-Type', 'text/xml']
]);
myHeaders.get('Content-Type') // should return 'text/xml'
| 规范 | 状态 | 注释 |
|---|---|---|
|
Fetch
The definition of 'Headers' in that specification. |
实时标准 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
头
|
Chrome
42
|
Edge ≤18 |
Firefox
39
|
IE No |
Opera
29
|
Safari 10.1 | WebView Android 42 |
Chrome Android
42
|
Firefox Android 44 |
Opera Android
29
|
Safari iOS No | Samsung Internet Android 4.0 |
Headers()
构造函数
|
Chrome
42
|
Edge
≤79
|
Firefox
39
|
IE No |
Opera
29
|
Safari 10.1 | WebView Android 42 |
Chrome Android
42
|
Firefox Android No |
Opera Android
29
|
Safari iOS No | Samsung Internet Android 4.0 |
append
|
Chrome
42
|
Edge 14 |
Firefox
39
|
IE No |
Opera
29
|
Safari 10.1 | WebView Android 42 |
Chrome Android
42
|
Firefox Android No |
Opera Android
29
|
Safari iOS No | Samsung Internet Android 4.0 |
delete
|
Chrome
42
|
Edge 14 |
Firefox
39
|
IE No |
Opera
29
|
Safari 10.1 | WebView Android 42 |
Chrome Android
42
|
Firefox Android No |
Opera Android
29
|
Safari iOS No | Samsung Internet Android 4.0 |
entries
|
Chrome 45 | Edge 16 | Firefox 44 | IE No | Opera 32 | Safari ? | WebView Android 45 | Chrome Android 45 | Firefox Android 44 | Opera Android 32 | Safari iOS No | Samsung Internet Android 5.0 |
get
|
Chrome
42
|
Edge 14 |
Firefox
52
|
IE No |
Opera
29
|
Safari 10.1 | WebView Android 42 |
Chrome Android
42
|
Firefox Android No |
Opera Android
29
|
Safari iOS No | Samsung Internet Android 4.0 |
getAll
弃用
非标
|
Chrome 42 — 60 | Edge ≤18 — 79 |
Firefox
39 — 52
|
IE No | Opera 29 — 47 | Safari No | WebView Android 42 — 60 | Chrome Android 42 — 60 | Firefox Android No | Opera Android 29 — 44 | Safari iOS No | Samsung Internet Android 4.0 |
has
|
Chrome
42
|
Edge 14 |
Firefox
39
|
IE No |
Opera
29
|
Safari No | WebView Android 42 |
Chrome Android
42
|
Firefox Android No |
Opera Android
29
|
Safari iOS No | Samsung Internet Android 4.0 |
keys
|
Chrome 45 | Edge 16 | Firefox 44 | IE No | Opera 32 | Safari ? | WebView Android 45 | Chrome Android 45 | Firefox Android 44 | Opera Android 32 | Safari iOS No | Samsung Internet Android 5.0 |
| Lexicographical sorting, and values from duplicate header names combined when iterated. | Chrome ? | Edge ? | Firefox 44 | IE No | Opera 28 | Safari No | WebView Android ? | Chrome Android ? | Firefox Android No | Opera Android ? | Safari iOS No | Samsung Internet Android ? |
set
|
Chrome
42
|
Edge 14 |
Firefox
39
|
IE No |
Opera
29
|
Safari No | WebView Android 42 |
Chrome Android
42
|
Firefox Android No |
Opera Android
29
|
Safari iOS No | Samsung Internet Android 4.0 |
值
|
Chrome 45 | Edge 16 | Firefox 44 | IE No | Opera 32 | Safari ? | WebView Android 45 | Chrome Android 45 | Firefox Android 44 | Opera Android 32 | Safari iOS No | Samsung Internet Android 5.0 |
完整支持
不支持
兼容性未知
实验。期望将来行为有所改变。
非标。预期跨浏览器支持较差。
弃用。不要用于新网站。
见实现注意事项。
用户必须明确启用此特征。