This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The ambient light events are a handy way to make a web page or an application aware of any change in the light intensity. It allows them to react to such a change, for example by changing the color contrast of the User Interface (UI) or by changing the exposure necessary to take a picture.
Light Events
When the light sensor of a device detects a change in the light level, it notifies the browser of that change. When the browser gets such a notification, it fires a DeviceLightEvent event that provides information about the exact light intensity.
This event can be captured at the window object level by using the addEventListener method (using the devicelight event name) or by attaching an event handler to the window.ondevicelight property.
Once captured, the event object gives access to the light intensity expressed in lux through the DeviceLightEvent.value property.
Example
window.addEventListener('devicelight', function(event) {
var html = document.getElementsByTagName('html')[0];
if (event.value < 50) {
html.classList.add('darklight');
html.classList.remove('brightlight');
} else {
html.classList.add('brightlight');
html.classList.remove('darklight');
}
});
Specifications
| Specification | Status | Comment |
|---|---|---|
| Ambient Light Sensor The definition of 'Ambient Light Events' in that specification. |
Editor's Draft | Initial definition |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
DeviceLightEvent |
No support | 22.0 (22.0)[1] | No support | No support | No support |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
DeviceLightEvent |
No support | support | 15.0 (15.0)[1] | No support | No support | No support |
[1] The devicelight event is implemented and preference enabled by default in Firefox Mobile for Android (15.0) and in Firefox OS (B2G). Starting with Gecko 22.0 (Firefox 22.0 / Thunderbird 22.0 / SeaMonkey 2.19) a desktop implementation for Mac OS X is also available. Support for Windows 7 is in progress (see bug 754199).