Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
 The onconnect property of the USB interface is an event handler called whenever a paired device is connected. It is passed an instance of USBConnectionEvent. 
USB.onconnect = connectFunction
| Specification | 
|---|
| WebUSB API  # ref-for-dom-usb-onconnect  | 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
onconnect | 
61  | 
79  | 
No  | 
No  | 
48  | 
No  | 
No  | 
61  | 
No  | 
45  | 
No  | 
8.0  | 
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    https://developer.mozilla.org/en-US/docs/Web/API/USB/onconnect