jQuery Mobile, extended search filter

$.mobile.listview.prototype.options.xFilter = false;
$.mobile.listview.prototype.options.xFilterId = false;

$( document ).delegate( ":jqmData(role='listview')", "listviewcreate", function() {

    var listview = $(this).data( "listview" );

    if ( !listview.options.xFilter || !$(this).attr('id') ) {
        return;
    }

    var list = $(this).add('ul:jqmData(x-filter-id='+$(this).attr('id')+')');

    if ( listview.options.filterReveal ) {
        list.children().addClass( "ui-screen-hidden" );
    }

    var wrapper = $( "<form>", {
            "class": "ui-listview-filter ui-bar-" + listview.options.filterTheme,
            "role": "search"
        }),
        search = $( "<input>", {
            placeholder: listview.options.filterPlaceholder
        })
        .attr( "data-" + $.mobile.ns + "type", "search" )
        .jqmData( "lastval", "" )
        .bind( "keyup change", function() {

            var $this = $( this ),
                val = this.value.toLowerCase(),
                listItems = null,
                lastval = $this.jqmData( "lastval" ) + "",
                childItems = false,
                itemtext = "",
                item,
                // Check if a custom filter callback applies
                isCustomFilterCallback = listview.options.filterCallback !== $.mobile.listview.prototype.options.filterCallback;

            listview._trigger( "beforefilter", "beforefilter", { input: this } );

            // Change val as lastval for next execution
            $this.jqmData( "lastval" , val );
            if ( isCustomFilterCallback || val.length < lastval.length || val.indexOf( lastval ) !== 0 ) {

                // Custom filter callback applies or removed chars or pasted something totally different, check all items
                listItems = list.children();
            } else {

                // Only chars added, not removed, only use visible subset
                listItems = list.children( ":not(.ui-screen-hidden)" );

                if ( !listItems.length && listview.options.filterReveal ) {
                    listItems = list.children( ".ui-screen-hidden" );
                }
            }

            if ( val ) {

                // This handles hiding regular rows without the text we search for
                // and any list dividers without regular rows shown under it

                for ( var i = listItems.length - 1; i >= 0; i-- ) {
                    item = $( listItems[ i ] );
                    itemtext = item.jqmData( "filtertext" ) || item.text();

                    if ( item.is( "li:jqmData(role=list-divider)" ) ) {

                        item.toggleClass( "ui-filter-hidequeue" , !childItems );

                        // New bucket!
                        childItems = false;

                    } else if ( listview.options.filterCallback( itemtext, val, item ) ) {

                        //mark to be hidden
                        item.toggleClass( "ui-filter-hidequeue" , true );
                    } else {

                        // There's a shown item in the bucket
                        childItems = true;
                    }
                }

                // Show items, not marked to be hidden
                listItems
                    .filter( ":not(.ui-filter-hidequeue)" )
                    .toggleClass( "ui-screen-hidden", false );

                // Hide items, marked to be hidden
                listItems
                    .filter( ".ui-filter-hidequeue" )
                    .toggleClass( "ui-screen-hidden", true )
                    .toggleClass( "ui-filter-hidequeue", false );

            } else {

                //filtervalue is empty => show all
                listItems.toggleClass( "ui-screen-hidden", !!listview.options.filterReveal );
            }
            listview._refreshCorners();
        })
        .appendTo( wrapper )
        .textinput();

    if ( listview.options.inset ) {
        wrapper.addClass( "ui-listview-filter-inset" );
    }

    wrapper.bind( "submit", function() {
        return false;
    })
    .insertBefore( $(this) );
});​