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At a regular interval, get the acceleration along the x, y, and z axis.
var watchID = navigator.accelerometer.watchAcceleration(accelerometerSuccess,
accelerometerError,
[accelerometerOptions]);
The accelerometer is a motion sensor that detects the change (delta) in movement relative to the current position. The accelerometer can detect 3D movement along the x, y, and z axis.
The accelerometer.watchAcceleration method retrieves the device‘s current Acceleration at a regular interval, executing the accelerometerSuccess callback function each time. Specify the interval in milliseconds via the acceleratorOptions object’s frequency parameter.
The returned watch ID references the accelerometer's watch interval, and can be used with accelerometer.clearWatch to stop watching the accelerometer.
function onSuccess(acceleration) {
alert('Acceleration X: ' + acceleration.x + '\n' +
'Acceleration Y: ' + acceleration.y + '\n' +
'Acceleration Z: ' + acceleration.z + '\n' +
'Timestamp: ' + acceleration.timestamp + '\n');
};
function onError() {
alert('onError!');
};
var options = { frequency: 3000 }; // Update every 3 seconds
var watchID = navigator.accelerometer.watchAcceleration(onSuccess, onError, options);
<!DOCTYPE html>
<html>
<head>
<title>Acceleration Example</title>
<script type="text/javascript" charset="utf-8" src="cordova.js"></script>
<script type="text/javascript" charset="utf-8">
// The watch id references the current `watchAcceleration`
var watchID = null;
// Wait for device API libraries to load
//
document.addEventListener("deviceready", onDeviceReady, false);
// device APIs are available
//
function onDeviceReady() {
startWatch();
}
// Start watching the acceleration
//
function startWatch() {
// Update acceleration every 3 seconds
var options = { frequency: 3000 };
watchID = navigator.accelerometer.watchAcceleration(onSuccess, onError, options);
}
// Stop watching the acceleration
//
function stopWatch() {
if (watchID) {
navigator.accelerometer.clearWatch(watchID);
watchID = null;
}
}
// onSuccess: Get a snapshot of the current acceleration
//
function onSuccess(acceleration) {
var element = document.getElementById('accelerometer');
element.innerHTML = 'Acceleration X: ' + acceleration.x + '<br />' +
'Acceleration Y: ' + acceleration.y + '<br />' +
'Acceleration Z: ' + acceleration.z + '<br />' +
'Timestamp: ' + acceleration.timestamp + '<br />';
}
// onError: Failed to get the acceleration
//
function onError() {
alert('onError!');
}
</script>
</head>
<body>
<div id="accelerometer">Waiting for accelerometer...</div>
</body>
</html>
The API calls the success callback function at the interval requested, but restricts the range of requests to the device between 40ms and 1000ms. For example, if you request an interval of 3 seconds, (3000ms), the API requests data from the device every 1 second, but only executes the success callback every 3 seconds.