positionfixed.js

// test for fixed positioning
Modernizr.addTest("positionfixed", function()
{
    // OK since iOS 5
    //if (navigator.userAgent.match(/AppleWebKit\/(.*)Mobile\//)) return false;
    if (navigator.userAgent.match(/Android(.*)Mobile/)) return false;

    var test = document.createElement("div"),
        control = test.cloneNode(false),
        fake = false,
        root = document.body || (function()
        {
            fake = true;
            return document.documentElement.appendChild(document.createElement("body"));
        }());

    var oldCssText = root.style.cssText;
    root.style.cssText = "padding:0;margin:0";
    test.style.cssText = "position:fixed;top:42px";
    root.appendChild(test);
    root.appendChild(control);

    var ret = test.offsetTop !== control.offsetTop;

    root.removeChild(test);
    root.removeChild(control);
    root.style.cssText = oldCssText;

    if (fake) document.documentElement.removeChild(root);
    return ret;
});