eventHandler.js

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

// defaultPrevented is broken in IE.
// https://connect.microsoft.com/IE/feedback/details/790389/event-defaultprevented-returns-false-after-preventdefault-was-called
const workingDefaultPrevented = (() => {
  const e = document.createEvent('CustomEvent')
  e.initEvent('Bootstrap', true, true)
  e.preventDefault()
  return e.defaultPrevented
})()

// CustomEvent polyfill for IE (see: https://mzl.la/2v76Zvn)
if (typeof window.CustomEvent !== 'function') {
  window.CustomEvent = (event, params) => {
    params = params || {
      bubbles: false,
      cancelable: false,
      detail: null
    }
    const evt = document.createEvent('CustomEvent')
    evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail)
    if (!workingDefaultPrevented) {
      const origPreventDefault = Event.prototype.preventDefault
      evt.preventDefault = () => {
        if (!evt.cancelable) {
          return
        }

        origPreventDefault.call(evt)
        Object.defineProperty(evt, 'defaultPrevented', {
          get() {
            return true
          },
          configurable: true
        })
      }
    }
    return evt
  }

  window.CustomEvent.prototype = window.Event.prototype
}

// Event constructor shim
if (!window.Event || typeof window.Event !== 'function') {
  const origEvent = window.Event
  window.Event = (inType, params) => {
    params = params || {}
    const e = document.createEvent('Event')
    e.initEvent(inType, Boolean(params.bubbles), Boolean(params.cancelable))
    return e
  }
  window.Event.prototype = origEvent.prototype
}

const namespaceRegex = /[^.]*(?=\..*)\.|.*/
const stripNameRegex = /\..*/

// Events storage
const eventRegistry = {}
let uidEvent = 1

function getUidEvent(element, uid) {
  return element.uidEvent = uid && `${uid}::${uidEvent++}` || element.uidEvent || uidEvent++
}

function getEvent(element) {
  const uid = getUidEvent(element)
  return eventRegistry[uid] = eventRegistry[uid] || {}
}

const nativeEvents = [
  'click', 'dblclick', 'mouseup', 'mousedown', 'contextmenu',
  'mousewheel', 'DOMMouseScroll',
  'mouseover', 'mouseout', 'mousemove', 'selectstart', 'selectend',
  'keydown', 'keypress', 'keyup',
  'orientationchange',
  'touchstart', 'touchmove', 'touchend', 'touchcancel',
  'gesturestart', 'gesturechange', 'gestureend',
  'focus', 'blur', 'change', 'reset', 'select', 'submit',
  'load', 'unload', 'beforeunload', 'resize', 'move', 'DOMContentLoaded', 'readystatechange',
  'error', 'abort', 'scroll'
]

function bootstrapHandler(element, fn) {
  return function (event) {
    return fn.apply(element, [event])
  }
}

function bootstrapDelegationHandler(selector, fn) {
  return function (event) {
    const domElements = document.querySelectorAll(selector)
    for (let target = event.target; target && target !== this; target = target.parentNode) {
      for (let i = domElements.length; i--;) {
        if (domElements[i] === target) {
          return fn.apply(target, [event])
        }
      }
    }
    // To please ESLint
    return null
  }
}

const EventHandler = {
  on(element, originalTypeEvent, handler, delegationFn) {
    if (typeof originalTypeEvent !== 'string' ||
        (typeof element === 'undefined' || element === null)) {
      return
    }

    const delegation = typeof handler === 'string'
    // allow to get the native events from namespaced events ('click.bs.button' --> 'click')
    let typeEvent = originalTypeEvent.replace(stripNameRegex, '')
    const isNative = nativeEvents.indexOf(typeEvent) > -1
    if (!isNative) {
      typeEvent = originalTypeEvent
    }
    const events    = getEvent(element)
    const handlers  = events[typeEvent] || (events[typeEvent] = {})
    const uid = getUidEvent(handler, originalTypeEvent.replace(namespaceRegex, ''))
    if (handlers[uid]) {
      return
    }

    const fn = !delegation ? bootstrapHandler(element, handler) : bootstrapDelegationHandler(handler, delegationFn)
    handlers[uid] = fn
    handler.uidEvent = uid
    element.addEventListener(typeEvent, fn, false)
  },

  one(element, event, handler) {
    function complete(e) {
      const typeEvent = event.replace(stripNameRegex, '')
      const events = getEvent(element)
      if (!events || !events[typeEvent]) {
        return
      }
      handler.apply(element, [e])
      EventHandler.off(element, event, complete)
    }
    EventHandler.on(element, event, complete)
  },

  off(element, originalTypeEvent, handler) {
    if (typeof originalTypeEvent !== 'string' ||
       (typeof element === 'undefined' || element === null)) {
      return
    }

    const typeEvent = originalTypeEvent.replace(stripNameRegex, '')
    const events = getEvent(element)
    if (!events || !events[typeEvent]) {
      return
    }

    const uidEvent = handler.uidEvent
    const fn = events[typeEvent][uidEvent]
    element.removeEventListener(typeEvent, fn, false)
    delete events[typeEvent][uidEvent]
  },

  trigger(element, event, args) {
    if (typeof event !== 'string' ||
        (typeof element === 'undefined' || element === null)) {
      return null
    }
    const typeEvent = event.replace(stripNameRegex, '')
    const isNative = nativeEvents.indexOf(typeEvent) > -1
    let returnedEvent = null
    if (isNative) {
      const evt = document.createEvent('HTMLEvents')
      evt.initEvent(typeEvent, true, true, typeof args !== 'undefined' ? args : {})
      element.dispatchEvent(evt)
      returnedEvent = evt
    } else {
      const eventToDispatch = new CustomEvent(event, {
        bubbles: true,
        cancelable: true,
        detail: typeof args !== 'undefined' ? args : {}
      })
      element.dispatchEvent(eventToDispatch)
      returnedEvent = eventToDispatch
    }
    return returnedEvent
  }
}

export default EventHandler