orientationchangeend

The orientationchangeend event is fired when the orientation of the device has changed and the associated rotation animation has been complete.

The Issue

orientationchange event is fired when the orientation of the device has changed.

– https://developer.mozilla.org/en-US/docs/Web/Events/orientationchange

This definition neglects to mention that the event is fired after window.orientation property has changed, but before the orientation is reflected in the UI. Inspecting dimensions of elements (e.g. window.innerWidth or window.innerHeight) gives the dimensions of the elements in the pre-orientation change state.

orientationchangeend is triggered at the end of the screen rotation animation that follows the orientation change event.

This has been developed for use with the mobile Safari, though the nature of the implementation makes it safe to use with other vendors.

The Underlying Implementation

There is no way to capture the end of the orientation change event because handling of the orientation change varies from browser to browser. Drawing a balance between the most reliable and the fastest way to detect the end of orientation change requires racing interval and timeout.

A listener is attached to the orientationchange. Invoking the listener starts an interval. The interval is tracking the state of the Rotation Indication Variable. The orientationchangeend event is fired when config.noChangeCountToEnd number of consequent iterations do not detect a value mutation or after config.noEndTimeout milliseconds, whichever happens first.

If you have suggestions for better strategy to detect the end of the orientationchange event, please raise an issue.

Rotation Indication Variable

The variable used to track the state of the rotation is a collection of window.innerWidth and window.innerHeight. This is a workaround until the Screen Orientation API becomes available in the iOS.

I realize that this is not a bullet-proof implementation. If you have suggestions for better variables to track the state of the rotation, please contribute to the Stack Overflow question or raise an issue.

Series of Events

If there is a series of orientationchange events fired one after another, where n event orientationchangeend event has not been fired before the n+2 orientationchange, then orientationchangeend will fire only for the last orientationchange event in the series.

Usage

var config = {},
    OCE;

// Start tracking the orientation change.
OCE = gajus.orientationchangeend(config);

// Attach event listener to the "orientationchangeend" event.
OCE.on('orientationchangeend', function () {
    // The orientation have changed.
});

Configuration

Name	Value	Default
noChangeCountToEnd	Number of iterations the subject of interval inspection must not mutate to fire orientationchangeend.	100
noEndTimeout	Number of milliseconds after which fire the orientationchangeend if interval inspection did not do it before.	1000
debug	Enables logging of the events	false

All of the configuration parameters are optional.

DOM Events

I did not make the event available to the window to avoid polluting the global scope and possible future conflicts.

To make the orientationchangeend event available to the window, re-emit the event using a custom event:

var orientationchangeend;

// Make sure that you are not adding event emitter more than once.
if ('onorientationchangeend' in window) {
    orientationchangeend = new CustomEvent('orientationchangeend');

    window.onorientationchangeend = OCE.on('orientationchangeend', function () {
        window.dispatchEvent(orientationchangeend);
    });    
}

// Attach a listener to the "orientationchangeend" event.
window.addEventListener('orientationchangeend', function () {
    console.log('The orientation of the device is now ' + window.orientation);
});

Download

Using Bower:

bower install orientationchangeend

Using NPM:

npm install orientationchangeend