WakeLockSentinel
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
The WakeLockSentinel
interface of the Screen Wake Lock API can be used to monitor the status of the platform screen wake lock, and manually release the lock when needed.
The screen wake lock prevents device screens from dimming or locking when an application needs to keep running.
A screen wake lock is requested using the navigator.wakeLock.request()
method, which returns a Promise
that fulfills with a WakeLockSentinel
object if the lock is granted.
An acquired screen wake lock can be released manually via the release()
method, or automatically via the platform screen wake lock. The latter may occur if the document becomes inactive or loses visibility, if the device is low on power, or if the user turns on a power save mode.
A released WakeLockSentinel
cannot be re-used: a new sentinel must be be requested using navigator.wakeLock.request()
if a new lock is needed.
Releasing all WakeLockSentinel
instances of a given wake lock type will cause the underlying platform wake lock to be released.
An event is fired at the WakeLockSentinel
if the platform lock is released, allowing applications to configure their UI, and re-request the lock if needed.
Instance properties
Also inherits properties from its parent interface, EventTarget
.
Instance methods
Also inherits methods from its parent interface, EventTarget
.
Events
Examples
In this example, we create an asynchronous function that requests a WakeLockSentinel
.
Once the screen wake lock is acquired we listen for the release
event, which can be used to give appropriate UI feedback.
The sentinel can be acquired or released via appropriate interactions.
// create a reference for the wake lock
let wakeLock = null;
// create an async function to request a wake lock
const requestWakeLock = async () => {
try {
wakeLock = await navigator.wakeLock.request("screen");
// listen for our release event
wakeLock.addEventListener("release", () => {
// if wake lock is released alter the UI accordingly
});
} catch (err) {
// if wake lock request fails - usually system related, such as battery
}
};
wakeLockOnButton.addEventListener("click", () => {
requestWakeLock();
});
wakeLockOffButton.addEventListener("click", () => {
if (wakeLock !== null) {
wakeLock.release().then(() => {
wakeLock = null;
});
}
});
Specifications
Specification |
---|
Screen Wake Lock API # the-wakelocksentinel-interface |
Browser compatibility
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