Gits for medium article: https://medium.com/p/1b2fee1721ec

collection.js

// collection.js
export function forEach (arr, callback) { ... }
export function map (arr, callback) { ... }
export function get (arr, id, key = 'id') { ... }
export function getIndex (arr, id, key = 'id') { ... }
export function add (arr, item, index = -1) { ... }
export function update (arr, id, values) { ... }
export function move (fromArr, id, toIndex, toArr = fromArr) { ... }
export function moveByIndex (fromArr, fromIndex, toIndex, toArr = fromArr) { ... }
export function remove (arr, id) { ... }

helper.js

import { move } from '@/common/utils/collection'

function onDragDrop (fromIndex, toIndex) {
  move(this.data.bookmarks, fromIndex, toIndex)
}

window-class.js

export default class Window {
  constructor (data) {
    this.title = data.title
    this.tabs = data.tabs
  }
  
  moveTab (from, to) { ... }
}
const window = new Window(data)
window.moveTab(1, 5)
const tabs = window.tabs

window-functional.js

// Window.js
// additional code omitted for clarity
import {
  get,
  add,
  update,
  move,
  remove
} from '@/common/utils/collection'

export default class Window {
  constructor (data = {}) { ... }

  updateTab (info) {
    return update(this, info)
  }

  getTab (tabId) {
    return get(this.tabs, tabId)
  }

  addTab (info, index = -1) {
    return add(this.tabs, Tab.create(info), index)
  }

  moveTab (tabId, toIndex) {
    return move(this.tabs, tabId, toIndex)
  }

  removeTab (tabId) {
    return remove(this.tabs, tabId)
  }
}

window-static.js

export default class Window {
  static moveTab (tabs, from, to) { ... }
  
  constructor (data) {
    this.title = data.title
    this.tabs = data.tabs
  }
}
  
Window.moveTab(data.tabs, 1, 5)

window-utility.js

export default class Window {
  constructor (data) {
    this.title = data.title
    this.tabs = data.tabs
  }
  
  moveTab (from, to) { ... }
}
  
function moveTab (tabs, from, to) { ... }

moveTab(data.tabs, 1, 5)

window-utility2.js

export default class Window {
  constructor (data) {
    this.title = data.title
    this.tabs = data.tabs
  }

reorder (from, to) {
    reorder(this.tabs, from, to) 
  }
}

function reorder (tabs, from, to) { ... }