Web/API/USBDevice/opened

This is an experimental technologyCheck the Browser compatibility table carefully before using this in production.

The 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.

Syntax

var serialNumber = USBDevice.opened

Value

A boolean.

Example

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);
   }
 }

Specifications

Specification	Status	Comment
WebUSBThe definition of 'opened' in that specification.	Draft	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`opened` Experimental'	Chrome Full support 61	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 48	Safari No support No	WebView Android No support No	Chrome Android Full support 61	Firefox Android No support No	Opera Android Full support 45	Safari iOS No support No	Samsung Internet Android Full support 8.0

Legend

Full support: Full support
No support: No support
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.

USBDevice.opened by Mozilla Contributors is licensed under CC-BY-SA 2.5.