append()
方法在
头
interface appends a new value onto an existing header inside a
头
object, or adds the header if it does not already exist.
差异在
set()
and
append()
is that if the specified header already exists and accepts multiple values,
set()
will overwrite the existing value with the new one, whereas
append()
will append the new value onto the end of the set of values.
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 .
myHeaders.append(name, value);
名称
头
对象。
value
The value of the HTTP header you want to add.
Void.
Creating an empty
头
object is simple:
var myHeaders = new Headers(); // Currently empty
You could add a header to this using
append()
:
myHeaders.append('Content-Type', 'image/jpeg');
myHeaders.get('Content-Type'); // Returns 'image/jpeg'
If the specified header already exists,
append()
will change its value to the specified value. If the specified header already exists and accepts multiple values,
append()
will append the new value to the end of the value set:
myHeaders.append('Accept-Encoding', 'deflate');
myHeaders.append('Accept-Encoding', 'gzip');
myHeaders.get('Accept-Encoding'); // Returns 'deflate, gzip'
To overwrite the old value with a new one, use
Headers.set
.
| 规范 | 状态 | 注释 |
|---|---|---|
|
Fetch
The definition of 'append()' in that specification. |
实时标准 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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 |
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。