在此页

• 句法
• 范例
• 规范
• 浏览器兼容性
• 相关话题

这是 实验性技术
检查 浏览器兼容性表格 要小心谨慎在生产中使用这之前。

opened read only property of the USBDevice interface indicates whether a session has been started with a paired USB device. A device must be opened before it can be controlled by a web page.

句法

var serialNumber = USBDevice.opened
					

值

A boolean .

范例

This example is for a hypothetical USB device with a multi-colored LED. It shows how to test that a device is open before calling USBDevice.controlTransferOut to set a specified LED color.

What data can be passed to a USB device and how it is passed is particular and unique to each device.

async setDeviceColor(usbDevice, r, g, b) {
   if (device.opened) {
     // This hypothetical USB device requires that the data passed to
     // it be in a Uint8Array.
     let payload = new Uint8Array([r, g, b]);
     await usbDevice.controlTransferOut({
       requestType: 'vendor',
       recipient: 'device',
       request: 1,
       value: 0,
       index: 0,
     }, payload);
   }
 }
					

规范

规范	状态	注释
WebUSB The definition of 'opened' 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
opened	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： Sep 23, 2019

相关话题

1. USBDevice
2. 特性

   1. configuration
   2. configurations
   3. deviceClass
   4. deviceClass
   5. deviceProtocol
   6. deviceSubclass
   7. deviceVersionMajor
   8. deviceVersionMinor
   9. deviceVersionSubminor
   10. manufacturerName
   11. opened
   12. productID
   13. productName
   14. serialNumber
   15. usbVersionMajor
   16. usbVersionMinor
   17. usbVersionSubminor
   18. vendorID
3. 方法

   1. claimInterface()
   2. clearHalt()
   3. close()
   4. controlTransferIn()
   5. controlTransferOut()
   6. isochronousTransferIn()
   7. isochronousTransferOut()
   8. open()
   9. releaseInterface()
   10. reset()
   11. selectAlternateInterface()
   12. selectConfiguration()
   13. transferIn()
   14. transferOut()