jQuery Mobile Fixed Toolbar

/*!
 jQuery Mobile fixedtoolbar polyfill for blacklisted browsers that don't natively support position:fixed
 Author @scottjehl
 Copyright 2012 Filament Group, Inc.
 License Dual MIT or GPLv2
*/
(function( $, undefined ) {

    // If the supportBlacklist is returning true, it's a blacklisted browser.
    if( $.mobile.fixedtoolbar.prototype.options.supportBlacklist() && $.support.scrollTop ){

        // Keep a reference to the original _create method
        var oldcreate = $.mobile.fixedtoolbar.prototype._create,

            // Additional scripting to add to the _create method for polyfilling unsupported browsers
            createPolyfill = function(){

                if( this.options.polyfillSupport === true ){

                    var toolbar = this.element,
                        tbType = toolbar.hasClass( "ui-header-fixed") ? "header" : "footer",
                        page = toolbar.closest( ":jqmData(role='page')" );

                        // Add faux support class to toolbar
                        toolbar.addClass( "ui-fixed-faux" );

                        // set up a function that resets the top or bottom value, depending on toolbar type
                        var resetPos = (function(){
                            if( tbType === "header" ){
                                return function(){
                                    toolbar.css( "top", $( window ).scrollTop() + "px" );
                                };
                            }
                            else {
                                return function(){

                                    toolbar.css( "bottom", page.outerHeight() - $( window).scrollTop() - $.mobile.getScreenHeight() + "px" );
                                }

                            }
                        })();

                        $.mobile.fixedtoolbar.prototype.updatePosition = resetPos;

                        // Per page show, re-set up the event handling
                        page.bind( "pagebeforeshow", function( e ){
                            var visible;

                            // Normalize proper object for scroll event
                            ( ( $( document ).scrollTop() === 0 ) ? $( window ) : $( document ) )
                                .bind( "scrollstart.fixedtoolbarpolyfill", function(){
                                    visible = toolbar.not( ".ui-fixed-hidden" ).fixedtoolbar( "hide", true );
                                })
                                .bind( "scrollstop.fixedtoolbarpolyfill", function(){
                                    resetPos();
                                    visible.fixedtoolbar( "show" );
                                });

                            // on resize, reset positioning
                            $( window ).bind( "throttledresize.fixedtoolbarpolyfill", resetPos );

                            // on pagehide, unbind the event handlers
                            page.one( "pagehide", function(){
                                $( this ).add( this ).add( document ).unbind( ".fixedtoolbarpolyfill" );
                            });

                            // align for pageshow
                            resetPos();
                    });
                }
            };

        // Set the blacklist test return false, letting any normally-blacklisted browsers in to be polyfilled
        $.mobile.fixedtoolbar.prototype.options.supportBlacklist = function(){
            return false;
        };

        // Define a new option for polyfillSupport, which can be disabled per call or via data attr data-polyfill-support
        $.mobile.fixedtoolbar.prototype.options.polyfillSupport = true;

        // Overwrite the _create method with the old and the new
        $.mobile.fixedtoolbar.prototype._create = function(){

            // Call the old _create method.
            oldcreate.call( this );

            // Call the polyfill scripting
            createPolyfill.call( this );
        };
    }

})( jQuery );