util.js

import $ from 'jquery'

/**
 * --------------------------------------------------------------------------
 * Bootstrap (v4.0.0-beta): util.js
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 * --------------------------------------------------------------------------
 */

const Util = (() => {


  /**
   * ------------------------------------------------------------------------
   * Private TransitionEnd Helpers
   * ------------------------------------------------------------------------
   */

  let transition = false

  const MAX_UID = 1000000

  const TransitionEndEvent = {
    WebkitTransition : 'webkitTransitionEnd',
    MozTransition    : 'transitionend',
    OTransition      : 'oTransitionEnd otransitionend',
    transition       : 'transitionend'
  }

  // shoutout AngusCroll (https://goo.gl/pxwQGp)
  function toType(obj) {
    return {}.toString.call(obj).match(/\s([a-zA-Z]+)/)[1].toLowerCase()
  }

  function getSpecialTransitionEndEvent() {
    return {
      bindType: transition.end,
      delegateType: transition.end,
      handle(event) {
        if ($(event.target).is(this)) {
          return event.handleObj.handler.apply(this, arguments) // eslint-disable-line prefer-rest-params
        }
        return undefined // eslint-disable-line no-undefined
      }
    }
  }

  function transitionEndTest() {
    if (window.QUnit) {
      return false
    }

    const el = document.createElement('bootstrap')

    for (const name in TransitionEndEvent) {
      if (typeof el.style[name] !== 'undefined') {
        return {
          end: TransitionEndEvent[name]
        }
      }
    }

    return false
  }

  function transitionEndEmulator(duration) {
    let called = false

    $(this).one(Util.TRANSITION_END, () => {
      called = true