combination filter with search

directory.js

jQuery(document).ready( function($) {

// debounce so filtering doesn't happen every millisecond
function debounce( fn, threshold ) {
  var timeout;
  return function debounced() {
    if ( timeout ) {
      clearTimeout( timeout );
    }
    function delayed() {
      fn();
      timeout = null;
    }
    setTimeout( delayed, threshold || 100 );
  };
}  


// initially hide noresult box on page load
$('#noResult').hide();

var qsRegex;
var filterValue;

  // init Isotope
  var $grid = $('#isotope-list').isotope({
    itemSelector: '.person',
    layoutMode: 'vertical',
    filter: function() {
      var $this = $(this);
      var searchResult = qsRegex ? $this.text().match( qsRegex ) : true;
      //Q: This variable is where the magic needs to happen
      var filterResult = filterValue ? $this.is( filterValue ) : true;
      return searchResult && filterResult;
    }
  });

    // layout Isotope again after all images have loaded
    $grid.imagesLoaded( function() {
        $grid.isotope('layout');
    });

    // SEARCH FUNCTION
    // use value of search field to filter
    var $quicksearch = $('#id_search').keyup( debounce( function() {
      qsRegex = new RegExp( $quicksearch.val(), 'gi' );
      $grid.isotope();
      // display message box if no filtered items
      if ( !$grid.data('isotope').filteredItems.length ) {
        $('#noResult').show();
      } else {
        $('#noResult').hide();
      }
    }) );
    //wrap up search function
    $('.filter-list li a').click(function(event){
      event.preventDefault();
    });

    // FILTER FUNCTION
    // Array to store filter from each group.
    var filters = {};
    $('.filter-list a').on('click', function() {
        // Get navigation group (subject or author) as object.
        var $navGroup = $(this).parents('.filter-list');
        // Get data-filter-group attribute for current nav group.
        var filterGroup = $navGroup.attr('data-filter-group');

        // If button is already active (checked):
        if ( $(this).hasClass('is-checked')) {
            $(this).removeClass('is-checked');
            // Reset array entry with filterGroup as key.
            filters[ filterGroup ] = '*';
        } else {
            // Find any checked buttons in the current filter group
            // and remove .checked class.
            $navGroup.find('a').removeClass('is-checked');
            // Set array entry with filterGroup as key to current data-filter value.
            filters[ filterGroup ] = $(this).attr('data-filter');
            $(this).addClass('is-checked');
        }
        // Grab concatenated filter values via concatenateValues function.
        filterValue = concatenateValues( filters );
        // Run the filter.
        $grid.isotope({ filter: filterValue });
    });

    // Concatenate values from array to a single string.
    function concatenateValues( object ) {
        var values = "";
        for ( var value in object ) {
            values += object[value];
        }
        return values;
    }   
});