The RTCDataChannel.onerror property is an event handler which specifies a function to be called when the error event is received. When an error occurs on the data channel, the function receives as input an RTCErrorEvent object describing the error which occurred. 
RTCDataChannel.onerror = function;
 A function which the browser will call to handle the error event when it occurs on the data channel. This function receives as its only input an ErrorEvent object describing the event which was received. That event object, in turn, describes the error that took place. 
 In the example below, a data channel is established, and an onerror handler is added to it. The error handler passes information about the error to a UI library's alert box function to present an error message to the user. 
let pc = new RTCPeerConnection(); let dc = pc.createDataChannel("PlayerControl"); dc.onerror = function(event) { myUILibrary.doAlertBox('Network Error', // Alert title `The error ${event.message} occurred while handling player control network messages`, // Error msg event.filename, event.lineno, event.colno); // Error location } /* ... */
| Specification | 
|---|
| WebRTC 1.0: Real-Time Communication Between Browsers (WebRTC 1.0) # dom-rtcdatachannel-onerror  | 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
onerror | 
24  | 
79  | 
22  | 
No  | 
15  | 
11  | 
≤37  | 
25  | 
22  | 
14  | 
11  | 
1.5  | 
error event and its type, ErrorEvent.
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    https://developer.mozilla.org/en-US/docs/Web/API/RTCDataChannel/onerror