在此页

• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

get() 方法在 头 interface returns a byte string of all the values of a header within a 头 object with a given name. If the requested header doesn't exist in the 头 object, it returns null .

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 .

句法

myHeaders.get(name);
					

参数

名称

The name of the HTTP header whose values you want to retrieve from the 头 object. If the given name is not the name of an HTTP header, this method throws a TypeError . The name is case-insensitive.

返回

A ByteString sequence representing the values of the retrieved header or null if this header is not set.

范例

Creating an empty 头 object is simple:

var myHeaders = new Headers(); // Currently empty
myHeaders.get('Not-Set'); // Returns null
					

You could add a header to this using Headers.append , then retrieve it using get() :

myHeaders.append('Content-Type', 'image/jpeg');
myHeaders.get('Content-Type'); // Returns "image/jpeg"
					

If the header has multiple values associated with it, the byte string will contain all the values, in the order they were added to the Headers object:

myHeaders.append('Accept-Encoding', 'deflate');
myHeaders.append('Accept-Encoding', 'gzip');
myHeaders.get('Accept-Encoding'); // Returns "deflate,gzip"
					

注意 : Headers.getAll used to have this functionality, with Headers.get returning only the first value added to the 头 object. The latest spec has removed getAll() , and updated get() to return all values.

规范

规范	状态	注释
Fetch The definition of 'get()' in that specification.	实时标准

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
get	Chrome 42 42 41 Disabled Disabled From version 41: this feature is behind the Experimental Web Platform Features preference. To change preferences in Chrome, visit chrome://flags.	Edge 14	Firefox 52 52 Prior to Firefox 52, get() only returned the first value in the specified header, with getAll() returning all values. From 52 onwards, get() now returns all values and getAll() has been deleted. 39 34 Disabled Disabled From version 34: this feature is behind the dom.fetch.enabled preference. To change preferences in Firefox, visit about:config.	IE No	Opera 29 29 28 Disabled Disabled From version 28: this feature is behind the Experimental Web Platform Features preference.	Safari 10.1	WebView Android 42	Chrome Android 42 42 41 Disabled Disabled From version 41: this feature is behind the Experimental Web Platform Features preference. To change preferences in Chrome, visit chrome://flags.	Firefox Android No	Opera Android 29 29 28 Disabled Disabled From version 28: this feature is behind the Experimental Web Platform Features preference.	Safari iOS No	Samsung Internet Android 4.0

图例

完整支持

完整支持

不支持

不支持

实验。期望将来行为有所改变。

实验。期望将来行为有所改变。

见实现注意事项。

用户必须明确启用此特征。

用户必须明确启用此特征。

另请参阅

• ServiceWorker API
• HTTP access control (CORS)
• HTTP

元数据

• 最后修改： 2019 年 3 月 23 日

相关话题

1. 头
2. 构造函数

   1. Headers()
3. 方法

   1. append()
   2. delete()
   3. entries()
   4. get()
   5. getAll()
   6. has()
   7. keys()
   8. set()
   9. values()