This is an experimental technology
Check 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 |
---|---|---|
WebUSB The definition of 'opened' in that specification. |
Draft | Initial definition. |
Browser compatibility
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.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
opened | 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.