在此页

• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

has() 方法在 头 interface returns a boolean stating whether a 头 object contains a certain header.

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.has(name);
					

参数

名称

The name of the HTTP header you want to test for. If the given name is not a valid HTTP header name, this method throws a TypeError .

返回

A 布尔 .

范例

Creating an empty 头 object is simple:

var myHeaders = new Headers(); // Currently empty
					

You could add a header to this using Headers.append , then test for the existence of it using has() :

myHeaders.append('Content-Type', 'image/jpeg');
myHeaders.has('Content-Type'); // Returns true
myHeaders.has('Accept-Encoding'); // Returns false
					

规范

规范	状态	注释
Fetch The definition of 'has()' 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
has	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 39 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 No	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。

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： Aug 5, 2020

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()