The onreading event handler is called when a reading is taken on one of the child interfaces of the Sensor interface. 
sensorInstance.onreading = function sensorInstance.addEventListener('reading', function() { ... })
 Because Sensor is a base class, onreading may only be used on one of its derived classes. 
| Specification | 
|---|
| Generic Sensor API  # sensor-onreading  | 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
onreading | 
67  | 
79  | 
No  | 
No  | 
54  | 
No  | 
67  | 
67  | 
No  | 
48  | 
No  | 
9.0  | 
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    https://developer.mozilla.org/en-US/docs/Web/API/Sensor/onreading