javascript - jQuery/JS, iOS 4 and $(document).height() problems

Question

I've run into an odd issue with what appears to be various versions of Webkit browsers. I'm trying to position an element on the center of the screen and to do the calculations, I need to get various dimensions, specifically the height of the body and the height of the screen. In jQuery I've been using:

var bodyHeight = $('body').height();
var screenHeight = $(window).height();

My page is typically much taller than the actual viewport, so when I 'alert' those variables, bodyHeight should end up being large, while screenHeight should remain constant (height of the browser viewport).

This is true in - Firefox - Chrome 15 (whoa! When did Chrome get to version 15?) - Safari on iOS5

This is NOT working in: - Safari on iOS4 - Safari 5.0.4

On the latter two, $(window).height(); always returns the same value as $('body').height()

Thinking it was perhaps a jQuery issue, I swapped out the window height for window.outerHeight but that, too, does the same thing, making me think this is actually some sort of webkit problem.

Has anyone ran into this and know of a way around this issue?

To complicate things, I can't seem to replicate this in isolation. For instance: http://jsbin.com/omogap/3 works fine.

I've determined it's not a CSS issue, so perhaps there's other JS wreaking havoc on this particular browser I need to find.

Answer 1

I've been fighting with this for a very long time (because of bug of my plugin) and I've found the way how to get proper height of window in Mobile Safari.

It works correctly no matter what zoom level is without subtracting height of screen with predefined height of status bars (which might change in future). And it works with iOS6 fullscreen mode.

Some tests (on iPhone with screen size 320x480, in landscape mode):

// Returns height of the screen including all toolbars
// Requires detection of orientation. (320px for our test)
window.orientation === 0 ? screen.height : screen.width


// Returns height of the visible area
// It decreases if you zoom in
window.innerHeight


// Returns height of screen minus all toolbars
// The problem is that it always subtracts it with height of the browser bar, no matter if it present or not
// In fullscreen mode it always returns 320px. 
// Doesn't change when zoom level is changed.
document.documentElement.clientHeight 

Here is how height is detected:

var getIOSWindowHeight = function() {
    // Get zoom level of mobile Safari
    // Note, that such zoom detection might not work correctly in other browsers
    // We use width, instead of height, because there are no vertical toolbars :)
    var zoomLevel = document.documentElement.clientWidth / window.innerWidth;

    // window.innerHeight returns height of the visible area. 
    // We multiply it by zoom and get out real height.
    return window.innerHeight * zoomLevel;
};

// You can also get height of the toolbars that are currently displayed
var getHeightOfIOSToolbars = function() {
    var tH = (window.orientation === 0 ? screen.height : screen.width) -  getIOSWindowHeight();
    return tH > 1 ? tH : 0;
};

Such technique has only one con: it's not pixel perfect when page is zoomed in (because window.innerHeight always returns rounded value). It also returns incorrect value when you zoom in near top bar.

One year passed since you asked this question, but anyway hope this helps! :)