notifications-admin/app/assets/javascripts/liveSearch.js

(function(Modules) {
  "use strict";

  let normalize = (string) => string.toLowerCase().replace(/ /g,'');

  let filter = ($searchBox, $targets) => () => {

    let query = normalize($searchBox.val());

    $targets.each(function() {

      let content = $('.live-search-relevant', this).text() || $(this).text();

      if ($(this).has(':checked').length) {
        $(this).show();
        return;
      }

      if (query == '') {
        $(this).css('display', '');
        return;
      }

      $(this).toggle(
        normalize(content).indexOf(normalize(query)) > -1
      );

    });

  };


  Modules.LiveSearch = function() {

    this.start = function(component) {

      let $component = $(component);

      let $searchBox = $('input', $component);

      let filterFunc = filter(
        $searchBox,
        $($component.data('targets'))
      );

      $searchBox.on('keyup input', filterFunc);

      filterFunc();

    };

  };

})(window.GOVUK.Modules);