set()
方法在
头
interface sets a new value for an existing header inside a
头
object, or adds the header if it does not already exist.
差异在
set()
and
Headers.append
is that if the specified header already exists and accepts multiple values,
set()
overwrites the existing value with the new one, whereas
Headers.append
appends the new value to the end of the set of values.
For security reasons, some headers can only be controller by the user agent. These headers include the forbidden header names and forbidden response header names .
myHeaders.set(name, value);
名称
TypeError
.
value
The new value you want to set.
Void.
Creating an empty
头
object is simple:
var myHeaders = new Headers(); // Currently empty
You could add a header to this using
Headers.append
, then set a new value for this header using
set()
:
myHeaders.append('Content-Type', 'image/jpeg');
myHeaders.set('Content-Type', 'text/html');
If the specified header does not already exist,
set()
will create it and set its value to the specified value. If the specified header does already exist and does accept multiple values,
set()
will overwrite the existing value with the new one:
myHeaders.set('Accept-Encoding', 'deflate');
myHeaders.set('Accept-Encoding', 'gzip');
myHeaders.get('Accept-Encoding'); // Returns 'gzip'
You'd need
Headers.append
to append the new value onto the values, not overwrite it.
| 规范 | 状态 | 注释 |
|---|---|---|
|
Fetch
The definition of 'set()' in that specification. |
实时标准 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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 |
完整支持
不支持
实验。期望将来行为有所改变。
用户必须明确启用此特征。