Fixed-fixed-fixed-oh-for-fucks-sake.js

/*! Fixedfixed: a CSS position:fixed qualifier. Original by Filament Group. (c)2012 @scottjehl, Filament Group, Inc. Dual license: MIT and/or GPLv2 */
(function( w, undefined ){

    var htmlclass = "fixed-supported",
        el = w.document.createElement( "div" ),
        ua = w.navigator.userAgent,
        docEl = w.document.documentElement;
  
    // fix the test element
    el.style.position = "fixed";
    el.style.top = 0;

    // support test
    function checkFixed(){

        var scroll = "scrollTop" in w.document.body ? w.document.body.scrollTop : docEl.scrollTop;

        // only run test if there's a scroll we can compare
        if( scroll !== undefined && scroll > 0 && w.document.body ){

            w.document.body.insertBefore( el, w.document.body.firstChild );

            if( !el.getBoundingClientRect || el.getBoundingClientRect().top !== 0 ) {
                // UA sniff + feature inference for iOS 8+, which has 
                // getBoundingClientRect, but reports it wrong for fixed
                // elements (it seems. Shit.). If not, opt out. 
                if (!(ua.match(/iPad|iPhone|iPod/) && !window.MSStream && !!window.indexedDB)) {
                    docEl.className = docEl.className.replace( htmlclass, "" );
                }
            }

            // remove the test element
            w.document.body.removeChild( el );

            // unbind the handlers
            if( w.removeEventListener ){
                w.removeEventListener( "scroll", checkFixed, false );
            }
            else{
                w.detachEvent( "onscroll", checkFixed );
            }
        }
    }

    // if a particular UA is known to return false results with this feature test, try and avoid that UA here.
    if(
        // Android 2.1, 2.2, 2.5, and 2.6 Webkit
        !( ua.match( /Android 2\.[1256]/ ) && ua.indexOf( "AppleWebKit") > -1 ) ||
        // Opera Mobile less than version 11.0 (7458)
        !( ua.match( /Opera Mobi\/([0-9]+)/ ) && RegExp.$1 < 7458 ) ||
        // Opera Mini
        !( w.operamini && ({}).toString.call( w.operamini ) === "[object OperaMini]" ) ||
        // Firefox Mobile less than version 6
        !( ua.match( /Fennec\/([0-9]+)/ ) && RegExp.$1 < 6 )
        // If necessary, add the other untestable browsers here...
    ){
        //add the HTML class for now.
        docEl.className += " " + htmlclass;

        // bind to scroll event so we can test and potentially degrade
        if( w.addEventListener ){
            w.addEventListener( "scroll", checkFixed, false );
        }
        else{
            w.attachEvent( "onscroll", checkFixed );
        }
    }

    w.FixedFixed = checkFixed;
}( this ));

I added the sniffing for iOS8+ (based on some random shit I found on the interwebz) to avoid the false negative. It seems that getBoundingClientRect() does not report correctly on iOS8-9, don't know if its because of the toolbar or what...

Oh, and this is not tested other than real quick on iOS9.

Hm, if you think we should merge something into fixed-fixed you should open an issue for discussion!

@zachleat – I'll try to do that. Noticed that there were a few pull requests open, but not much activity so I figured it might not be actively developed any more...