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• 构造函数
• 特性
• 范例
• 规范
• 浏览器兼容性
• 相关话题

安全上下文
此特征只可用于 安全上下文 (HTTPS)，在某些或所有 支持浏览器 .

USBEndpoint 接口在 WebUSB API provides information about an endpoint provided by the USB device. An endpoint represents a unidirectional data stream into or out of a device.

构造函数

USBEndpoint.USBEndpoint

创建新的 USBEndpoint object which will be populated with information about the endpoint on the provided USBAltenateInterface with the given endpoint number and transfer direction.

特性

USBEndpoint.endpointNumber

Returns this endpoint's "endpoint number" which is a value from 1 to 15 extracted from the bEndpointAddress field of the endpoint descriptor defining this endpoint. This value is used to identify the endpoint when calling methods on USBDevice .

USBEndpoint.direction

Returns the direction in which this endpoint transfers data, one of:

• "in" - Data is transferred from device to host.

• "out" - Data is transferred from host to device.

USBEndpoint.type

Returns the type of this endpoint, one of:

• "bulk" - Provides reliable data transfer for large payloads. Data sent through a bulk endpoint is guaranteed to be delivered or generate an error but may be preempted by other data traffic.

• "interrupt" - Provides reliable data transfer for small payloads. Data sent through an interrupt endpoint is guaranteed to be delivered or generate an error and is also given dedicated bus time for transmission.

• "isochronous" - Provides unreliable data transfer for payloads that must be delivered periodically. They are given dedicated bus time but if a deadline is missed the data is dropped.

USBEndpoint.packetSize

Returns the size of the packets that data sent through this endpoint will be divided into.

范例

While sometimes the developer knows ahead of time the exact layout of a device's endpoints there are cases where this must be discovered at runtime. For example, a USB serial device must provide bulk input and output endpoints but their endpoint numbers will depend on what other interfaces the device provides.

This code identifies the correct endpoints by searching for the interface implementing the USB CDC interface class and then identifying the candidate endpoints based on their type and direction.

let inEndpoint = undefined;
let outEndpoint = undefined;
for (const interface of device.configuration.interfaces) {
  // Only support devices with out multiple alternate interfaces.
  const alternate = interface.alternates[0];
  // Identify the interface implementing the USB CDC class.
  const USB_CDC_CLASS = 10;
  if (alternate.interfaceClass != USB_CDC_CLASS) {
    continue;
  }
  for (const endpoint of alternate.endpoints) {
    // Identify the bulk transfer endpoints.
    if (endpoint.type != "bulk") {
      continue;
    }
    if (endpoint.direction == "in") {
      inEndpoint = endpoint.endpointNumber;
    } else if (endpoint.direction == "out") {
      outEndpoint = endpoint.endpointNumber;
    }
  }
}
					

规范

规范	状态	注释
WebUSB The definition of 'USBEndPoint' in that specification.	草案	初始定义。

浏览器兼容性

The compatibility table in 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
USBEndpoint	Chrome 61	Edge 79	Firefox No	IE No	Opera 48	Safari No	WebView Android No	Chrome Android 61	Firefox Android No	Opera Android 45	Safari iOS No	Samsung Internet Android 8.0
USBEndpoint() 构造函数	Chrome 61	Edge 79	Firefox No	IE No	Opera 48	Safari No	WebView Android No	Chrome Android 61	Firefox Android No	Opera Android 45	Safari iOS No	Samsung Internet Android 8.0
direction	Chrome 61	Edge 79	Firefox No	IE No	Opera 48	Safari No	WebView Android No	Chrome Android 61	Firefox Android No	Opera Android 45	Safari iOS No	Samsung Internet Android 8.0
endpointNumber	Chrome 61	Edge 79	Firefox No	IE No	Opera 48	Safari No	WebView Android No	Chrome Android 61	Firefox Android No	Opera Android 45	Safari iOS No	Samsung Internet Android 8.0
packetSize	Chrome 61	Edge 79	Firefox No	IE No	Opera 48	Safari No	WebView Android No	Chrome Android 61	Firefox Android No	Opera Android 45	Safari iOS No	Samsung Internet Android 8.0
type	Chrome 61	Edge 79	Firefox No	IE No	Opera 48	Safari No	WebView Android No	Chrome Android 61	Firefox Android No	Opera Android 45	Safari iOS No	Samsung Internet Android 8.0

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。

元数据

• 最后修改： May 15, 2020