Detect rotation of Android phone in the browser with JavaScript

The actual behavior across different devices is inconsistent. The resize and orientationChange events can fire in a different sequence with varying frequency. Also, some values (e.g. screen.width and window.orientation) don't always change when you expect. Avoid screen.width -- it doesn't change when rotating in iOS.

The reliable approach is to listen to both resize and orientationChange events (with some polling as a safety catch), and you'll eventually get a valid value for the orientation. In my testing, Android devices occasionally fail to fire events when rotating a full 180 degrees, so I've also included a setInterval to poll the orientation.

var previousOrientation = window.orientation;var checkOrientation = function(){    if(window.orientation !== previousOrientation){        previousOrientation = window.orientation;        // orientation changed, do your magic here    }};window.addEventListener("resize", checkOrientation, false);window.addEventListener("orientationchange", checkOrientation, false);// (optional) Android doesn't always fire orientationChange on 180 degree turnssetInterval(checkOrientation, 2000);

Here are the results from the four devices that I've tested (sorry for the ASCII table, but it seemed like the easiest way to present the results). Aside from the consistency between the iOS devices, there is a lot of variety across devices. NOTE: The events are listed in the order that they fired.

|==============================================================================||     Device     | Events Fired      | orientation | innerWidth | screen.width ||==============================================================================|| iPad 2         | resize            | 0           | 1024       | 768          || (to landscape) | orientationchange | 90          | 1024       | 768          ||----------------+-------------------+-------------+------------+--------------|| iPad 2         | resize            | 90          | 768        | 768          || (to portrait)  | orientationchange | 0           | 768        | 768          ||----------------+-------------------+-------------+------------+--------------|| iPhone 4       | resize            | 0           | 480        | 320          || (to landscape) | orientationchange | 90          | 480        | 320          ||----------------+-------------------+-------------+------------+--------------|| iPhone 4       | resize            | 90          | 320        | 320          || (to portrait)  | orientationchange | 0           | 320        | 320          ||----------------+-------------------+-------------+------------+--------------|| Droid phone    | orientationchange | 90          | 320        | 320          || (to landscape) | resize            | 90          | 569        | 569          ||----------------+-------------------+-------------+------------+--------------|| Droid phone    | orientationchange | 0           | 569        | 569          || (to portrait)  | resize            | 0           | 320        | 320          ||----------------+-------------------+-------------+------------+--------------|| Samsung Galaxy | orientationchange | 0           | 400        | 400          || Tablet         | orientationchange | 90          | 400        | 400          || (to landscape) | orientationchange | 90          | 400        | 400          ||                | resize            | 90          | 683        | 683          ||                | orientationchange | 90          | 683        | 683          ||----------------+-------------------+-------------+------------+--------------|| Samsung Galaxy | orientationchange | 90          | 683        | 683          || Tablet         | orientationchange | 0           | 683        | 683          || (to portrait)  | orientationchange | 0           | 683        | 683          ||                | resize            | 0           | 400        | 400          ||                | orientationchange | 0           | 400        | 400          ||----------------+-------------------+-------------+------------+--------------|

To detect an orientation change on an Android browser, attach a listener to the orientationchange or resize event on window:

// Detect whether device supports orientationchange event, otherwise fall back to// the resize event.var supportsOrientationChange = "onorientationchange" in window,    orientationEvent = supportsOrientationChange ? "orientationchange" : "resize";window.addEventListener(orientationEvent, function() {    alert('HOLY ROTATING SCREENS BATMAN:' + window.orientation + " " + screen.width);}, false);

Check the window.orientation property to figure out which way the device is oriented. With Android phones, screen.width or screen.height also updates as the device is rotated. (this is not the case with the iPhone).

two-bit-fool's excellent answer provides all the background, but let me attempt a concise, pragmatic summary of how to handle orientation changes across iOS and Android:

• If you only care about window dimensions (the typical scenario) - and not about the specific orientation:
  • Handle the resize event only.
  • In your handler, act on window.innerWidth and window.InnerHeight only.
  • Do NOT use window.orientation - it won't be current on iOS.

• If you DO care about the specific orientation:
  • Handle only the resize event on Android, and only the orientationchange event on iOS.
  • In your handler, act on window.orientation (and window.innerWidth and window.InnerHeight)

These approaches offer slight benefits over remembering the previous orientation and comparing:

• the dimensions-only approach also works while developing on desktop browsers that can otherwise simulate mobile devices, e.g., Chrome 23. (window.orientation is not available on desktop browsers).
• no need for a global/anonymous-file-level-function-wrapper-level variable.