Events
There are various events provided by cordova to be used by the application. The application code could add listeners for these events. For example:
HTML File
<!DOCTYPE html>
<html>
<head>
<title>Device Ready Example</title>
<script type="text/javascript" charset="utf-8" src="cordova.js"></script>
<script type="text/javascript" charset="utf-8" src="example.js"></script>
</head>
<body onload="onLoad()">
</body>
</html>
JS File
// example.js file
// Wait for device API libraries to load
//
function onLoad() {
document.addEventListener("deviceready", onDeviceReady, false);
}
// device APIs are available
//
function onDeviceReady() {
document.addEventListener("pause", onPause, false);
document.addEventListener("resume", onResume, false);
document.addEventListener("menubutton", onMenuKeyDown, false);
// Add similar listeners for other events
}
function onPause() {
// Handle the pause event
}
function onResume() {
// Handle the resume event
}
function onMenuKeyDown() {
// Handle the menubutton event
}
// Add similar event handlers for other events
Note: Applications typically should use document.addEventListener
to attach an event listener once the deviceready
The following table lists the cordova events and the supported platforms:
Supported Platforms/ Events | android | ios | Windows |
---|---|---|---|
deviceready | |||
pause | |||
resume | |||
backbutton | |||
menubutton | |||
searchbutton | |||
startcallbutton | |||
endcallbutton | |||
volumedownbutton | |||
volumeupbutton | |||
activated |
deviceready
The deviceready event fires when Cordova is fully loaded. This event is essential to any application. It signals that Cordova's device APIs have loaded and are ready to access.
Cordova consists of two code bases: native and JavaScript. While the native code loads, a custom loading image displays. However, JavaScript only loads once the DOM loads. This means the web app may potentially call a Cordova JavaScript function before the corresponding native code becomes available.
The deviceready
event fires once Cordova has fully loaded. Once the
event fires, you can safely make calls to Cordova APIs. Applications
typically attach an event listener with document.addEventListener
once the HTML document's DOM has loaded.
The deviceready
event behaves somewhat differently from others. Any
event handler registered after the deviceready
event fires has its
callback function called immediately.
Quick Example
document.addEventListener("deviceready", onDeviceReady, false);
function onDeviceReady() {
// Now safe to use device APIs
}
pause
The pause event fires when the native platform puts the application into the background, typically when the user switches to a different application.
Quick Example
document.addEventListener("pause", onPause, false);
function onPause() {
// Handle the pause event
}
iOS Quirks
In the pause
handler, any calls to the Cordova API or to native
plugins that go through Objective-C do not work, along with any
interactive calls, such as alerts or console.log()
. They are only
processed when the app resumes, on the next run loop.
The iOS-specific resign
event is available as an alternative to
pause
, and detects when users enable the Lock button to lock the
device with the app running in the foreground. If the app (and
device) is enabled for multi-tasking, this is paired with a subsequent
pause
event, but only under iOS 5. In effect, all locked apps in iOS
5 that have multi-tasking enabled are pushed to the background. For
apps to remain running when locked under iOS 5, disable the app's
multi-tasking by setting UIApplicationExitsOnSuspend
to YES
. To run when locked on iOS 4, this setting does not matter.
resume
The resume
event fires when the native platform pulls the application out from the background.
Quick Example
document.addEventListener("resume", onResume, false);
function onResume() {
// Handle the resume event
}
iOS Quirks
Any interactive functions called from a pause event handler execute
later when the app resumes, as signaled by the resume
event. These
include alerts, console.log()
, and any calls from plugins or the
Cordova API, which go through Objective-C.
active event
The iOS-specific
active
event is available as an alternative toresume
, and detects when users disable the Lock button to unlock the device with the app running in the foreground. If the app (and device) is enabled for multi-tasking, this is paired with a subsequentresume
event, but only under iOS 5. In effect, all locked apps in iOS 5 that have multi-tasking enabled are pushed to the background. For apps to remain running when locked under iOS 5, disable the app's multi-tasking by setting UIApplicationExitsOnSuspend toYES
. To run when locked on iOS 4, this setting does not matter.resume event
When called from a
resume
event handler, interactive functions such asalert()
need to be wrapped in asetTimeout()
call with a timeout value of zero, or else the app hangs. For example:document.addEventListener("resume", onResume, false); function onResume() { setTimeout(function() { // TODO: do your thing! }, 0); }
Android Quirks
Refer Android Life Cycle Guide for details on android quirks with
the resume
event.
backbutton
The event fires when the user presses the back button. To override the default
back-button behavior, register an event listener for the backbutton
event.
It is no longer necessary to call any other method to override the
back-button behavior.
Quick Example
document.addEventListener("backbutton", onBackKeyDown, false);
function onBackKeyDown() {
// Handle the back button
}
Windows Quirks
Throw an error in a backbutton
callback to force the default behavior, which is an app exit:
document.addEventListener('backbutton', function (evt) {
if (cordova.platformId !== 'windows') {
return;
}
if (window.location.href !== firstPageUrl) {
window.history.back();
} else {
throw new Error('Exit'); // This will suspend the app
}
}, false);
menubutton
The event fires when the user presses the menu button. Applying an event handler overrides the default menu button behavior.
Quick Example
document.addEventListener("menubutton", onMenuKeyDown, false);
function onMenuKeyDown() {
// Handle the back button
}
searchbutton
The event fires when the user presses the search button on Android. If you need to override the default search button behavior on Android you can register an event listener for the 'searchbutton' event.
Quick Example
document.addEventListener("searchbutton", onSearchKeyDown, false);
function onSearchKeyDown() {
// Handle the search button
}
startcallbutton
The event fires when the user presses the start call button. If you need to override
the default start call behavior you can register an event listener for the startcallbutton
event.
Quick Example
document.addEventListener("startcallbutton", onStartCallKeyDown, false);
function onStartCallKeyDown() {
// Handle the start call button
}
endcallbutton
This event fires when the user presses the end call button. The event overrides the default end call behavior.
Quick Example
document.addEventListener("endcallbutton", onEndCallKeyDown, false);
function onEndCallKeyDown() {
// Handle the end call button
}
volumedownbutton
The event fires when the user presses the volume down button. If you need to override
the default volume down behavior you can register an event listener for the volumedownbutton
event.
Quick Example
document.addEventListener("volumedownbutton", onVolumeDownKeyDown, false);
function onVolumeDownKeyDown() {
// Handle the volume down button
}
volumeupbutton
The event fires when the user presses the volume up button. If you need to override
the default volume up behavior you can register an event listener for the volumeupbutton
event.
Quick Example
document.addEventListener("volumeupbutton", onVolumeUpKeyDown, false);
function onVolumeUpKeyDown() {
// Handle the volume up button
}
activated
The event fires when Windows Runtime activation has occurred. See MSDN docs for further details and activation types.
Quick Example
document.addEventListener("activated", activated, false);
function activated(args) {
if (args && args.kind === Windows.ApplicationModel.Activation.ActivationKind.file) {
// Using args.raw to get the native StorageFile object
Windows.Storage.FileIO.readTextAsync(args.raw.detail[0].files[0]).done(function (text) {
console.log(text);
}, function (err) {
console.error(err);
});
}
}
Windows Quirks
Original activated event args are available in
args.raw.detail[0]
property and can be used to get a type information or invoke methods of one of the activation arguments,Original activated event args are also cloned to
args.detail[0]
and can be used as a fallback in case an inner args property has been lost.
See https://issues.apache.org/jira/browse/CB-10653 for details.activated
event might be fired beforedeviceready
so you should save the activation flag and args to the app context in case you need them - for example in the Share target case. The subscription to theactivated
event should be done beforedeviceready
handler (inapp.bindEvents
in terms of the Cordova template).