Javascript max viewport height after orientation change Android & iOS

androidhtmliosjavascriptmobile

The Goal:

To find the max viewport height of a device including the space of the address bar so that we can dynamically resize the min-body and push our content up.

The Problem:

Mobile browsers handle orientation states differently and update DOM properties on orientation change differently.

Detect rotation of Android phone in the browser with JavaScript

With Android phones, screen.width or screen.height also updates as the device is rotated.

|==============================================================================|
|     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          |

Because of this it is clear that to find the max viewport height no matter what orientation, using a single function to return the max height of a device will never be constant over a range of devices.

Other problems I have discovered that don't make these two play nice:

The window.devicePixelRatio property can return inconsistent heights
when dividing by window.outerHeight.
Delay window.setTimeout(function() {}, time) needs to be used to give DOM elements a chance to update after orientation change.
window.outerHeight is not updated on orientation changes for iOS devices. Using screen.availHeight as a fallback includes the bottom nav bar as total height.
Using a #header, #content, #footer structure forces you to dynamically recalculate the #content{min-height} to push the #footer down when the body is dyamically updated.

A Solution:

First let's take a look at DIV structure:

<style>
#header,#content,#footer{width:100%;}
</style>

<body>
<div id="header"></div>
<div id="content"></div>
<div id="footer"></div>
</body>

We want to prevent devices from scaling on their own:

<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no" />

We need help to have the ability to return a max viewport height and hide address bar for iOS:

<script src="iOS.js" type="text/javascript"></script>

http://iosjs.com/

Then detect if the device supports orientation change and use resize as a fallback:

var iOS = (navigator.userAgent.match(/(iPad|iPhone|iPod)/i) ? true : false);
var android = (navigator.userAgent.match(/Android/i) ? true : false);
var supportsOrientationChange = "onorientationchange" in window;
var orientationEvent = supportsOrientationChange ? "orientationchange" : "resize";

The belly of the beast:

function updateOrientation()
{
    var orientation = (window.orientation);

    if(android)
    {
        window.setTimeout(function() {
            window.scrollTo(0,0);
            var size = window.outerHeight/window.devicePixelRatio;
            $('body').css('min-height', size + 'px');
            var headerHeight = $('#header').height();
            var footerHeight = $('#footer').height();
            var contentHeight = size - (headerHeight+footerHeight);
            $('#content').css('min-height', contentHeight + 'px');
            window.scrollTo(0,1);
        }, 200);
    }

    if(iOS)
    {
        window.setTimeout(function(){
            window.scrollTo(0,0);
            var size = iOS_getViewportSize();
            var headerHeight = $('#header').height();
            var footerHeight = $('#footer').height();
            var contentHeight = size.height - (headerHeight+footerHeight);
            $('#content').css('min-height', contentHeight + 'px');
            window.scrollTo(0,1);
        }, 0);
    }
}

Add event listeners for page load and orientation event:

if(iOS)
{
    iOS_addEventListener(window, "load", iOS_handleWindowLoad);
    iOS_addEventListener(window, "orientationchange", iOS_handleOrientationChange);
    iOS_addEventListener(window, "resize", iOS_handleReize);
}
addEventListener("load", function() 
{
    updateOrientation();
}, false);
addEventListener(orientationEvent, function() {
    updateOrientation();
}, false);

Proof is in the pudding:

iPhone 4 & 4s Portrait & Landscape

iPhone 4 & 4s Portrait
iPhone 4 & 4s Landscape

Android Portrait & Landscape

Android Portrait
Android Landscape

The goal here is to minify this solution or make it better.

Best Answer

This is a simple solution that will append the browsers width and height to the document body on load and window resize.

jQuery.event.add(window, "load", resize);
jQuery.event.add(window, "resize", resize);

  function resize() 
    {
      var h = jQuery(window).height();
      var w = jQuery(window).width();
      jQuery("body").css({"width": w, "height": h});
    }

Modern HTML5 Techniques for changing classes

Modern browsers have added classList which provides methods to make it easier to manipulate classes without needing a library:

document.getElementById("MyElement").classList.add('MyClass');

document.getElementById("MyElement").classList.remove('MyClass');

if ( document.getElementById("MyElement").classList.contains('MyClass') )

document.getElementById("MyElement").classList.toggle('MyClass');

Unfortunately, these do not work in Internet Explorer prior to v10, though there is a shim to add support for it to IE8 and IE9, available from this page. It is, though, getting more and more supported.

Simple cross-browser solution

The standard JavaScript way to select an element is using document.getElementById("Id"), which is what the following examples use - you can of course obtain elements in other ways, and in the right situation may simply use this instead - however, going into detail on this is beyond the scope of the answer.

To change all classes for an element:

To replace all existing classes with one or more new classes, set the className attribute:

document.getElementById("MyElement").className = "MyClass";

(You can use a space-delimited list to apply multiple classes.)

To add an additional class to an element:

To add a class to an element, without removing/affecting existing values, append a space and the new classname, like so:

document.getElementById("MyElement").className += " MyClass";

To remove a class from an element:

To remove a single class to an element, without affecting other potential classes, a simple regex replace is required:

document.getElementById("MyElement").className =
   document.getElementById("MyElement").className.replace
      ( /(?:^|\s)MyClass(?!\S)/g , '' )
/* Code wrapped for readability - above is all one statement */

An explanation of this regex is as follows:

(?:^|\s) # Match the start of the string or any single whitespace character

MyClass  # The literal text for the classname to remove

(?!\S)   # Negative lookahead to verify the above is the whole classname
         # Ensures there is no non-space character following
         # (i.e. must be the end of the string or space)

The g flag tells the replace to repeat as required, in case the class name has been added multiple times.

To check if a class is already applied to an element:

The same regex used above for removing a class can also be used as a check as to whether a particular class exists:

if ( document.getElementById("MyElement").className.match(/(?:^|\s)MyClass(?!\S)/) )

### Assigning these actions to onclick events:

Whilst it is possible to write JavaScript directly inside the HTML event attributes (such as onclick="this.className+=' MyClass'") this is not recommended behaviour. Especially on larger applications, more maintainable code is achieved by separating HTML markup from JavaScript interaction logic.

The first step to achieving this is by creating a function, and calling the function in the onclick attribute, for example:

<script type="text/javascript">
    function changeClass(){
        // Code examples from above
    }
</script>
...
<button onclick="changeClass()">My Button</button>

_{(It is not required to have this code in script tags, this is simply for the brevity of example, and including the JavaScript in a distinct file may be more appropriate.)}

The second step is to move the onclick event out of the HTML and into JavaScript, for example using addEventListener

<script type="text/javascript">
    function changeClass(){
        // Code examples from above
    }

    window.onload = function(){
        document.getElementById("MyElement").addEventListener( 'click', changeClass);
    }
</script>
...
<button id="MyElement">My Button</button>

(Note that the window.onload part is required so that the contents of that function are executed after the HTML has finished loading - without this, the MyElement might not exist when the JavaScript code is called, so that line would fail.)

JavaScript Frameworks and Libraries

The above code is all in standard JavaScript, however, it is common practice to use either a framework or a library to simplify common tasks, as well as benefit from fixed bugs and edge cases that you might not think of when writing your code.

Whilst some people consider it overkill to add a ~50 KB framework for simply changing a class, if you are doing any substantial amount of JavaScript work or anything that might have unusual cross-browser behavior, it is well worth considering.

(Very roughly, a library is a set of tools designed for a specific task, whilst a framework generally contains multiple libraries and performs a complete set of duties.)

The examples above have been reproduced below using jQuery, probably the most commonly used JavaScript library (though there are others worth investigating too).

(Note that $ here is the jQuery object.)

Changing Classes with jQuery:

$('#MyElement').addClass('MyClass');

$('#MyElement').removeClass('MyClass');

if ( $('#MyElement').hasClass('MyClass') )

In addition, jQuery provides a shortcut for adding a class if it doesn't apply, or removing a class that does:

$('#MyElement').toggleClass('MyClass');

### Assigning a function to a click event with jQuery:

$('#MyElement').click(changeClass);

or, without needing an id:

$(':button:contains(My Button)').click(changeClass);

Ios – How to change the name of an iOS app

Go to Targets in Xcode.
Build Settings on your project's target (your current development name).
Search for Product Name under Packaging. Change its value to what you want your new project name to be.