How to use the panel.apply function in panel

Stopwatch.Panel = function(element) {
    Panel.apply(this, arguments);

    this.nodes = {};
    this.lapTemplate = Template(lapHtml);
    this.interval = null;
    this.screenWakeLock = null;

    // Store maxLaps as a dataset attribute for easy access in tests.
    this.element.dataset.maxLaps = MAX_STOPWATCH_LAPS;
    this.element.innerHTML = html;
    // Gather elements
    [
      'start', 'pause', 'resume',
      'lap', 'reset', 'time',
      'lap-list', 'laps'
    ].forEach(function(sel) {
      this.nodes[sel] = this.element.querySelector('.stopwatch-' + sel);

Stopwatch.Panel = function(element) {
    Panel.apply(this, arguments);

    this.nodes = {};
    this.lapTemplate = new Template('lap-list-item-tmpl');
    this.interval = null;

    // Gather elements
    [
      'start', 'pause', 'resume',
      'lap', 'reset', 'time',
      'lap-list', 'laps'
    ].forEach(function(sel) {
      this.nodes[sel] = this.element.querySelector('.stopwatch-' + sel);
    }, this);

    // Bind click events
    [

function AlarmPanel() {
  Panel.apply(this, arguments);

  this.element.innerHTML = html;
  ClockView.init();
  this.alarmListPanel = new AlarmListPanel(document.getElementById('alarms'));
  this.activeAlarm = new ActiveAlarm();
}

Timer.Panel = function(element) {
  Panel.apply(this, arguments);

  element.innerHTML = html;
  this.timer = null;
  this.nodes = {};

  this.picker = new Picker({
    element: this.element.querySelector('#time-picker'),
    pickers: {
      hours: {
        range: [0, 23],
        l10nId: 'nSpinnerHours'
      },
      minutes: {
        range: [0, 59],
        isPadded: true,
        l10nId: 'nSpinnerMinutes'

var AlarmEdit = function() {
  Panel.apply(this, arguments);
  this.element.innerHTML = html;

  var handleDomEvent = this.handleDomEvent.bind(this);

  this.element.addEventListener('panel-visibilitychange',
                                this.handleVisibilityChange.bind(this));

  this.selects = {};
  [
    'time', 'repeat', 'sound', 'snooze'
  ].forEach(function(id) {
    this.selects[id] = this.element.querySelector('#' + id + '-select');
  }, this);

  this.inputs = {
    name: this.element.querySelector('#alarm-name'),

Timer.Panel = function(element) {
  Panel.apply(this, arguments);

  element.innerHTML = html;
  this.timer = null;
  this.nodes = {};

  this.picker = new Picker({
    element: this.element.querySelector('#time-picker'),
    pickers: {
      hours: {
        range: [0, 23],
        l10nId: 'nSpinnerHours'
      },
      minutes: {
        range: [0, 59],
        isPadded: true,
        l10nId: 'nSpinnerMinutes'