util.js

import $ from 'jquery'

/**
 * --------------------------------------------------------------------------
 * Bootstrap (v4.0.0): 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

  // Shoutout AngusCroll (https://goo.gl/pxwQGp)
  function toType(obj) {
    return {}.toString.call(obj).match(/\s([a-z]+)/i)[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 (typeof window !== 'undefined' && window.QUnit) {
      return false
    }

    return {
      end: 'transitionend'
    }
  }

  function transitionEndEmulator(duration) {
    let called = false

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

    setTimeout(() => {
      if (!called) {
        Util.triggerTransitionEnd(this)
      }
    }, duration)

    return this
  }

  function setTransitionEndSupport() {
    transition = transitionEndTest()

    $.fn.emulateTransitionEnd = transitionEndEmulator

    if (Util.supportsTransitionEnd()) {