How to use the backbone.Model.extend function in backbone

import {Model} from 'backbone';
import DataSource from 'background/model/dataSource';
import YouTubeV3API from 'background/model/youTubeV3API';

// TODO: This doesn't update the index of playlist items on sequence change
var ChromeContextMenusManager = Model.extend({
  defaults: {
    textSelectionPlayId: -1,
    textSelectionAddId: -1,
    youTubeLinkPlayId: -1,
    youTubeLinkAddId: -1,
    youTubeLinkSaveId: -1,
    youTubePagePlayId: -1,
    youTubePageAddId: -1,
    youTubePageSaveId: -1,
    streamItems: null,
    settings: null,
    tabManager: null,
    signInManager: null
  },

  initialize: function() {

import {Model} from 'backbone';
import LocalStorage from 'lib/backbone.localStorage';
import StreamItems from 'background/collection/streamItems';
import RelatedVideosManager from 'background/model/relatedVideosManager';
import PlayerState from 'common/enum/playerState';
import RepeatButtonState from 'common/enum/repeatButtonState';

var Stream = Model.extend({
  localStorage: new LocalStorage('Stream'),

  defaults: function() {
    return {
      // Need to set the ID for Backbone.LocalStorage
      id: 'Stream',
      items: new StreamItems(),
      activeItem: null,
      relatedVideosManager: new RelatedVideosManager(),
      history: [],
      player: null,
      shuffleButton: null,
      radioButton: null,
      repeatButton: null
    };
  },

import {Model} from 'backbone';
import ClientErrors from 'background/collection/clientErrors';

var ClientErrorManager = Model.extend({
  defaults: function() {
    return {
      platformInfo: {
        os: '',
        arch: ''
      },
      language: '',
      signInManager: null,
      reportedErrors: new ClientErrors()
    };
  },

  initialize: function() {
    chrome.runtime.getPlatformInfo(this._onChromeRuntimeGetPlatformInfo.bind(this));

    // It's important to bind pre-emptively or attempts to call removeEventListener will fail to find the appropriate reference.

import {Model} from 'backbone';

var ClientError = Model.extend({
  defaults: function() {
    return {
      instanceId: StreamusBG.instanceId,
      message: '',
      lineNumber: -1,
      url: '',
      clientVersion: chrome.runtime.getManifest().version,
      browserVersion: this._getBrowserVersion(),
      operatingSystem: '',
      architecture: '',
      stack: '',
      error: null,
      userId: ''
    };
  },

'use strict';
import {Model} from 'backbone';

var VideoStream = Model.extend({
  defaults: {
    currentTime: 0,
    muted: false,
    volume: 50,
    suggestedQuality: 'default',
    isSeeking: false
  }
});

export default VideoStream;

import { Model } from 'backbone';
import RouteType from 'route/routeType.js';

export default Model.extend({
  defaults: {
    route: RouteType.NotFound,
    isActive: false,
    isSecondary: false,
    text: ''
  }
});

import {Model} from 'backbone';

var TimeSlider = Model.extend({
  defaults: {
    currentTime: 0,
    isBeingDragged: false,
    isEnabled: false,
    player: null
  },

  initialize: function() {
    var player = this.get('player');
    this._setEnabledState(player.get('loadedVideo'));
    this.listenTo(player, 'change:loadedVideo', this._onPlayerChangeLoadedVideo);
  },

  incrementCurrentTime: function(incrementValue) {
    var incrementedCurrentTime = this.get('currentTime') + incrementValue;
    this.set('currentTime', incrementedCurrentTime);

'use strict';
import {Model} from 'backbone';

var SaveStreamButton = Model.extend({
  defaults: {
    enabled: false,
    streamItems: null,
    signInManager: null
  },

  initialize: function() {
    var streamItems = this.get('streamItems');
    this.listenTo(streamItems, 'add:completed', this._onStreamItemsAddCompleted);
    this.listenTo(streamItems, 'remove', this._onStreamItemsRemove);
    this.listenTo(streamItems, 'reset', this._onStreamItemsReset);

    var signInManager = this.get('signInManager');
    this.listenTo(signInManager, 'change:signedInUser', this._onSignInManagerChangeSignedInUser);
    this._setEnabled(signInManager.has('signedInUser'), streamItems.isEmpty());
  },

import {Model} from 'backbone';

export default Model.extend({
  schema: {
    first: {
      type: 'Text',
      title: 'First Name',
      validators: ['required'],
    },
    last: {
      type: 'Text',
      title: 'Last Name',
      validators: ['required']
    },
    phone: {
      type: 'Text',
      validators: ['phone']
    },
    primary_website: {

import {Model} from 'backbone';
import moment from 'moment';

/**
 * @class SearchResultModel
 */
const SearchResult = Model.extend({
    defaults() {
        return {
            id: null,
            etag: null,
            kind: null,
            videoId: null,
            channelId: null,
            description: '',
            publishedAt: null,
            thumbnails: null,
            title: ''
        };
    },

    parse(response) {
        return {