Merge branch 'twbs/v4-dev' into dropdown-keyboard

11 files changed, 418 insertions, 349 deletions

diff --git a/js/src/alert.js b/js/src/alert.js
index 4cb006ea3..884a5dec8 100644
--- a/js/src/alert.js
+++ b/js/src/alert.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): alert.js
+ * Bootstrap (v4.0.0-alpha.5): alert.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,7 +18,7 @@ const Alert = (($) => {
    */
 
   const NAME                = 'alert'
-  const VERSION             = '4.0.0-alpha.2'
+  const VERSION             = '4.0.0-alpha.5'
   const DATA_KEY            = 'bs.alert'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
@@ -38,7 +38,7 @@ const Alert = (($) => {
   const ClassName = {
     ALERT : 'alert',
     FADE  : 'fade',
-    IN    : 'in'
+    SHOW  : 'show'
   }
 
 
@@ -67,8 +67,8 @@ const Alert = (($) => {
     close(element) {
       element = element || this._element
 
-      let rootElement = this._getRootElement(element)
-      let customEvent = this._triggerCloseEvent(rootElement)
+      const rootElement = this._getRootElement(element)
+      const customEvent = this._triggerCloseEvent(rootElement)
 
       if (customEvent.isDefaultPrevented()) {
         return
@@ -86,8 +86,8 @@ const Alert = (($) => {
     // private
 
     _getRootElement(element) {
-      let selector = Util.getSelectorFromElement(element)
-      let parent   = false
+      const selector = Util.getSelectorFromElement(element)
+      let parent     = false
 
       if (selector) {
         parent = $(selector)[0]
@@ -101,14 +101,14 @@ const Alert = (($) => {
     }
 
     _triggerCloseEvent(element) {
-      let closeEvent = $.Event(Event.CLOSE)
+      const closeEvent = $.Event(Event.CLOSE)
 
       $(element).trigger(closeEvent)
       return closeEvent
     }
 
     _removeElement(element) {
-      $(element).removeClass(ClassName.IN)
+      $(element).removeClass(ClassName.SHOW)
 
       if (!Util.supportsTransitionEnd() ||
           !$(element).hasClass(ClassName.FADE)) {
@@ -117,7 +117,7 @@ const Alert = (($) => {
       }
 
       $(element)
-        .one(Util.TRANSITION_END, $.proxy(this._destroyElement, this, element))
+        .one(Util.TRANSITION_END, (event) => this._destroyElement(element, event))
         .emulateTransitionEnd(TRANSITION_DURATION)
     }
 
@@ -133,8 +133,8 @@ const Alert = (($) => {
 
     static _jQueryInterface(config) {
       return this.each(function () {
-        let $element = $(this)
-        let data     = $element.data(DATA_KEY)
+        const $element = $(this)
+        let data       = $element.data(DATA_KEY)
 
         if (!data) {
           data = new Alert(this)
diff --git a/js/src/button.js b/js/src/button.js
index 39e2b3974..45e1424ff 100644
--- a/js/src/button.js
+++ b/js/src/button.js
@@ -1,6 +1,6 @@
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): button.js
+ * Bootstrap (v4.0.0-alpha.5): button.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -15,7 +15,7 @@ const Button = (($) => {
    */
 
   const NAME                = 'button'
-  const VERSION             = '4.0.0-alpha.2'
+  const VERSION             = '4.0.0-alpha.5'
   const DATA_KEY            = 'bs.button'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
@@ -66,12 +66,12 @@ const Button = (($) => {
 
     toggle() {
       let triggerChangeEvent = true
-      let rootElement        = $(this._element).closest(
+      const rootElement      = $(this._element).closest(
         Selector.DATA_TOGGLE
       )[0]
 
       if (rootElement) {
-        let input = $(this._element).find(Selector.INPUT)[0]
+        const input = $(this._element).find(Selector.INPUT)[0]
 
         if (input) {
           if (input.type === 'radio') {
@@ -80,7 +80,7 @@ const Button = (($) => {
               triggerChangeEvent = false
 
             } else {
-              let activeElement = $(rootElement).find(Selector.ACTIVE)[0]
+              const activeElement = $(rootElement).find(Selector.ACTIVE)[0]
 
               if (activeElement) {
                 $(activeElement).removeClass(ClassName.ACTIVE)
@@ -90,7 +90,7 @@ const Button = (($) => {
 
           if (triggerChangeEvent) {
             input.checked = !$(this._element).hasClass(ClassName.ACTIVE)
-            $(this._element).trigger('change')
+            $(input).trigger('change')
           }
 
           input.focus()
@@ -151,7 +151,7 @@ const Button = (($) => {
       Button._jQueryInterface.call($(button), 'toggle')
     })
     .on(Event.FOCUS_BLUR_DATA_API, Selector.DATA_TOGGLE_CARROT, (event) => {
-      let button = $(event.target).closest(Selector.BUTTON)[0]
+      const button = $(event.target).closest(Selector.BUTTON)[0]
       $(button).toggleClass(ClassName.FOCUS, /^focus(in)?$/.test(event.type))
     })
 
diff --git a/js/src/carousel.js b/js/src/carousel.js
index 34cab4391..9a1a668b2 100644
--- a/js/src/carousel.js
+++ b/js/src/carousel.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): carousel.js
+ * Bootstrap (v4.0.0-alpha.5): carousel.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,12 +18,14 @@ const Carousel = (($) => {
    */
 
   const NAME                = 'carousel'
-  const VERSION             = '4.0.0-alpha.2'
+  const VERSION             = '4.0.0-alpha.5'
   const DATA_KEY            = 'bs.carousel'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
   const JQUERY_NO_CONFLICT  = $.fn[NAME]
   const TRANSITION_DURATION = 600
+  const ARROW_LEFT_KEYCODE  = 37 // KeyboardEvent.which value for left arrow key
+  const ARROW_RIGHT_KEYCODE = 39 // KeyboardEvent.which value for right arrow key
 
   const Default = {
     interval : 5000,
@@ -43,7 +45,9 @@ const Carousel = (($) => {
 
   const Direction = {
     NEXT     : 'next',
-    PREVIOUS : 'prev'
+    PREV     : 'prev',
+    LEFT     : 'left',
+    RIGHT    : 'right'
   }
 
   const Event = {
@@ -60,8 +64,10 @@ const Carousel = (($) => {
     CAROUSEL : 'carousel',
     ACTIVE   : 'active',
     SLIDE    : 'slide',
-    RIGHT    : 'right',
-    LEFT     : 'left',
+    RIGHT    : 'carousel-item-right',
+    LEFT     : 'carousel-item-left',
+    NEXT     : 'carousel-item-next',
+    PREV     : 'carousel-item-prev',
     ITEM     : 'carousel-item'
   }
 
@@ -69,7 +75,7 @@ const Carousel = (($) => {
     ACTIVE      : '.active',
     ACTIVE_ITEM : '.active.carousel-item',
     ITEM        : '.carousel-item',
-    NEXT_PREV   : '.next, .prev',
+    NEXT_PREV   : '.carousel-item-next, .carousel-item-prev',
     INDICATORS  : '.carousel-indicators',
     DATA_SLIDE  : '[data-slide], [data-slide-to]',
     DATA_RIDE   : '[data-ride="carousel"]'
@@ -114,9 +120,10 @@ const Carousel = (($) => {
     // public
 
     next() {
-      if (!this._isSliding) {
-        this._slide(Direction.NEXT)
+      if (this._isSliding) {
+        throw new Error('Carousel is sliding')
       }
+      this._slide(Direction.NEXT)
     }
 
     nextWhenVisible() {
@@ -127,9 +134,10 @@ const Carousel = (($) => {
     }
 
     prev() {
-      if (!this._isSliding) {
-        this._slide(Direction.PREVIOUS)
+      if (this._isSliding) {
+        throw new Error('Carousel is sliding')
       }
+      this._slide(Direction.PREVIOUS)
     }
 
     pause(event) {
@@ -159,7 +167,8 @@ const Carousel = (($) => {
 
       if (this._config.interval && !this._isPaused) {
         this._interval = setInterval(
-          $.proxy(document.visibilityState ? this.nextWhenVisible : this.next, this), this._config.interval
+          (document.visibilityState ? this.nextWhenVisible : this.next).bind(this),
+          this._config.interval
         )
       }
     }
@@ -167,9 +176,9 @@ const Carousel = (($) => {
     to(index) {
       this._activeElement = $(this._element).find(Selector.ACTIVE_ITEM)[0]
 
-      let activeIndex = this._getItemIndex(this._activeElement)
+      const activeIndex = this._getItemIndex(this._activeElement)
 
-      if (index > (this._items.length - 1) || index < 0) {
+      if (index > this._items.length - 1 || index < 0) {
         return
       }
 
@@ -184,7 +193,7 @@ const Carousel = (($) => {
         return
       }
 
-      let direction = index > activeIndex ?
+      const direction = index > activeIndex ?
         Direction.NEXT :
         Direction.PREVIOUS
 
@@ -217,28 +226,33 @@ const Carousel = (($) => {
     _addEventListeners() {
       if (this._config.keyboard) {
         $(this._element)
-          .on(Event.KEYDOWN, $.proxy(this._keydown, this))
+          .on(Event.KEYDOWN, (event) => this._keydown(event))
       }
 
       if (this._config.pause === 'hover' &&
         !('ontouchstart' in document.documentElement)) {
         $(this._element)
-          .on(Event.MOUSEENTER, $.proxy(this.pause, this))
-          .on(Event.MOUSELEAVE, $.proxy(this.cycle, this))
+          .on(Event.MOUSEENTER, (event) => this.pause(event))
+          .on(Event.MOUSELEAVE, (event) => this.cycle(event))
       }
     }
 
     _keydown(event) {
-      event.preventDefault()
-
       if (/input|textarea/i.test(event.target.tagName)) {
         return
       }
 
       switch (event.which) {
-        case 37: this.prev(); break
-        case 39: this.next(); break
-        default: return
+        case ARROW_LEFT_KEYCODE:
+          event.preventDefault()
+          this.prev()
+          break
+        case ARROW_RIGHT_KEYCODE:
+          event.preventDefault()
+          this.next()
+          break
+        default:
+          return
       }
     }
 
@@ -248,29 +262,29 @@ const Carousel = (($) => {
     }
 
     _getItemByDirection(direction, activeElement) {
-      let isNextDirection = direction === Direction.NEXT
-      let isPrevDirection = direction === Direction.PREVIOUS
-      let activeIndex     = this._getItemIndex(activeElement)
-      let lastItemIndex   = (this._items.length - 1)
-      let isGoingToWrap   = (isPrevDirection && activeIndex === 0) ||
-                            (isNextDirection && activeIndex === lastItemIndex)
+      const isNextDirection = direction === Direction.NEXT
+      const isPrevDirection = direction === Direction.PREVIOUS
+      const activeIndex     = this._getItemIndex(activeElement)
+      const lastItemIndex   = this._items.length - 1
+      const isGoingToWrap   = isPrevDirection && activeIndex === 0 ||
+                              isNextDirection && activeIndex === lastItemIndex
 
       if (isGoingToWrap && !this._config.wrap) {
         return activeElement
       }
 
-      let delta     = direction === Direction.PREVIOUS ? -1 : 1
-      let itemIndex = (activeIndex + delta) % this._items.length
+      const delta     = direction === Direction.PREVIOUS ? -1 : 1
+      const itemIndex = (activeIndex + delta) % this._items.length
 
       return itemIndex === -1 ?
         this._items[this._items.length - 1] : this._items[itemIndex]
     }
 
 
-    _triggerSlideEvent(relatedTarget, directionalClassname) {
-      let slideEvent = $.Event(Event.SLIDE, {
+    _triggerSlideEvent(relatedTarget, eventDirectionName) {
+      const slideEvent = $.Event(Event.SLIDE, {
         relatedTarget,
-        direction: directionalClassname
+        direction: eventDirectionName
       })
 
       $(this._element).trigger(slideEvent)
@@ -284,7 +298,7 @@ const Carousel = (($) => {
           .find(Selector.ACTIVE)
           .removeClass(ClassName.ACTIVE)
 
-        let nextIndicator = this._indicatorsElement.children[
+        const nextIndicator = this._indicatorsElement.children[
           this._getItemIndex(element)
         ]
 
@@ -295,22 +309,32 @@ const Carousel = (($) => {
     }
 
     _slide(direction, element) {
-      let activeElement = $(this._element).find(Selector.ACTIVE_ITEM)[0]
-      let nextElement   = element || activeElement &&
+      const activeElement = $(this._element).find(Selector.ACTIVE_ITEM)[0]
+      const nextElement   = element || activeElement &&
         this._getItemByDirection(direction, activeElement)
 
-      let isCycling = Boolean(this._interval)
+      const isCycling = Boolean(this._interval)
 
-      let directionalClassName = direction === Direction.NEXT ?
-        ClassName.LEFT :
-        ClassName.RIGHT
+      let directionalClassName
+      let orderClassName
+      let eventDirectionName
+
+      if (direction === Direction.NEXT) {
+        directionalClassName = ClassName.LEFT
+        orderClassName = ClassName.NEXT
+        eventDirectionName = Direction.LEFT
+      } else {
+        directionalClassName = ClassName.RIGHT
+        orderClassName = ClassName.PREV
+        eventDirectionName = Direction.RIGHT
+      }
 
       if (nextElement && $(nextElement).hasClass(ClassName.ACTIVE)) {
         this._isSliding = false
         return
       }
 
-      let slideEvent = this._triggerSlideEvent(nextElement, directionalClassName)
+      const slideEvent = this._triggerSlideEvent(nextElement, eventDirectionName)
       if (slideEvent.isDefaultPrevented()) {
         return
       }
@@ -328,15 +352,15 @@ const Carousel = (($) => {
 
       this._setActiveIndicatorElement(nextElement)
 
-      let slidEvent = $.Event(Event.SLID, {
+      const slidEvent = $.Event(Event.SLID, {
         relatedTarget: nextElement,
-        direction: directionalClassName
+        direction: eventDirectionName
       })
 
       if (Util.supportsTransitionEnd() &&
         $(this._element).hasClass(ClassName.SLIDE)) {
 
-        $(nextElement).addClass(direction)
+        $(nextElement).addClass(orderClassName)
 
         Util.reflow(nextElement)
 
@@ -346,15 +370,10 @@ const Carousel = (($) => {
         $(activeElement)
           .one(Util.TRANSITION_END, () => {
             $(nextElement)
-              .removeClass(directionalClassName)
-              .removeClass(direction)
-
-            $(nextElement).addClass(ClassName.ACTIVE)
+              .removeClass(`${directionalClassName} ${orderClassName}`)
+              .addClass(ClassName.ACTIVE)
 
-            $(activeElement)
-              .removeClass(ClassName.ACTIVE)
-              .removeClass(direction)
-              .removeClass(directionalClassName)
+            $(activeElement).removeClass(`${ClassName.ACTIVE} ${orderClassName} ${directionalClassName}`)
 
             this._isSliding = false
 
@@ -382,13 +401,13 @@ const Carousel = (($) => {
     static _jQueryInterface(config) {
       return this.each(function () {
         let data      = $(this).data(DATA_KEY)
-        let _config = $.extend({}, Default, $(this).data())
+        const _config = $.extend({}, Default, $(this).data())
 
         if (typeof config === 'object') {
           $.extend(_config, config)
         }
 
-        let action = typeof config === 'string' ? config : _config.slide
+        const action = typeof config === 'string' ? config : _config.slide
 
         if (!data) {
           data = new Carousel(this, _config)
@@ -410,20 +429,20 @@ const Carousel = (($) => {
     }
 
     static _dataApiClickHandler(event) {
-      let selector = Util.getSelectorFromElement(this)
+      const selector = Util.getSelectorFromElement(this)
 
       if (!selector) {
         return
       }
 
-      let target = $(selector)[0]
+      const target = $(selector)[0]
 
       if (!target || !$(target).hasClass(ClassName.CAROUSEL)) {
         return
       }
 
-      let config     = $.extend({}, $(target).data(), $(this).data())
-      let slideIndex = this.getAttribute('data-slide-to')
+      const config     = $.extend({}, $(target).data(), $(this).data())
+      const slideIndex = this.getAttribute('data-slide-to')
 
       if (slideIndex) {
         config.interval = false
@@ -452,7 +471,7 @@ const Carousel = (($) => {
 
   $(window).on(Event.LOAD_DATA_API, () => {
     $(Selector.DATA_RIDE).each(function () {
-      let $carousel = $(this)
+      const $carousel = $(this)
       Carousel._jQueryInterface.call($carousel, $carousel.data())
     })
   })
diff --git a/js/src/collapse.js b/js/src/collapse.js
index 3dd07cadf..ad8815993 100644
--- a/js/src/collapse.js
+++ b/js/src/collapse.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): collapse.js
+ * Bootstrap (v4.0.0-alpha.5): collapse.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,7 +18,7 @@ const Collapse = (($) => {
    */
 
   const NAME                = 'collapse'
-  const VERSION             = '4.0.0-alpha.2'
+  const VERSION             = '4.0.0-alpha.5'
   const DATA_KEY            = 'bs.collapse'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
@@ -44,7 +44,7 @@ const Collapse = (($) => {
   }
 
   const ClassName = {
-    IN         : 'in',
+    SHOW       : 'show',
     COLLAPSE   : 'collapse',
     COLLAPSING : 'collapsing',
     COLLAPSED  : 'collapsed'
@@ -56,7 +56,7 @@ const Collapse = (($) => {
   }
 
   const Selector = {
-    ACTIVES     : '.panel > .in, .panel > .collapsing',
+    ACTIVES     : '.card > .show, .card > .collapsing',
     DATA_TOGGLE : '[data-toggle="collapse"]'
   }
 
@@ -104,7 +104,7 @@ const Collapse = (($) => {
     // public
 
     toggle() {
-      if ($(this._element).hasClass(ClassName.IN)) {
+      if ($(this._element).hasClass(ClassName.SHOW)) {
         this.hide()
       } else {
         this.show()
@@ -112,8 +112,11 @@ const Collapse = (($) => {
     }
 
     show() {
-      if (this._isTransitioning ||
-        $(this._element).hasClass(ClassName.IN)) {
+      if (this._isTransitioning) {
+        throw new Error('Collapse is transitioning')
+      }
+
+      if ($(this._element).hasClass(ClassName.SHOW)) {
         return
       }
 
@@ -121,7 +124,7 @@ const Collapse = (($) => {
       let activesData
 
       if (this._parent) {
-        actives = $.makeArray($(Selector.ACTIVES))
+        actives = $.makeArray($(this._parent).find(Selector.ACTIVES))
         if (!actives.length) {
           actives = null
         }
@@ -134,7 +137,7 @@ const Collapse = (($) => {
         }
       }
 
-      let startEvent = $.Event(Event.SHOW)
+      const startEvent = $.Event(Event.SHOW)
       $(this._element).trigger(startEvent)
       if (startEvent.isDefaultPrevented()) {
         return
@@ -147,7 +150,7 @@ const Collapse = (($) => {
         }
       }
 
-      let dimension = this._getDimension()
+      const dimension = this._getDimension()
 
       $(this._element)
         .removeClass(ClassName.COLLAPSE)
@@ -164,11 +167,11 @@ const Collapse = (($) => {
 
       this.setTransitioning(true)
 
-      let complete = () => {
+      const complete = () => {
         $(this._element)
           .removeClass(ClassName.COLLAPSING)
           .addClass(ClassName.COLLAPSE)
-          .addClass(ClassName.IN)
+          .addClass(ClassName.SHOW)
 
         this._element.style[dimension] = ''
 
@@ -182,8 +185,8 @@ const Collapse = (($) => {
         return
       }
 
-      let capitalizedDimension = dimension[0].toUpperCase() + dimension.slice(1)
-      let scrollSize           = `scroll${capitalizedDimension}`
+      const capitalizedDimension = dimension[0].toUpperCase() + dimension.slice(1)
+      const scrollSize           = `scroll${capitalizedDimension}`
 
       $(this._element)
         .one(Util.TRANSITION_END, complete)
@@ -193,19 +196,22 @@ const Collapse = (($) => {
     }
 
     hide() {
-      if (this._isTransitioning ||
-        !$(this._element).hasClass(ClassName.IN)) {
+      if (this._isTransitioning) {
+        throw new Error('Collapse is transitioning')
+      }
+
+      if (!$(this._element).hasClass(ClassName.SHOW)) {
         return
       }
 
-      let startEvent = $.Event(Event.HIDE)
+      const startEvent = $.Event(Event.HIDE)
       $(this._element).trigger(startEvent)
       if (startEvent.isDefaultPrevented()) {
         return
       }
 
-      let dimension       = this._getDimension()
-      let offsetDimension = dimension === Dimension.WIDTH ?
+      const dimension       = this._getDimension()
+      const offsetDimension = dimension === Dimension.WIDTH ?
         'offsetWidth' : 'offsetHeight'
 
       this._element.style[dimension] = `${this._element[offsetDimension]}px`
@@ -215,7 +221,7 @@ const Collapse = (($) => {
       $(this._element)
         .addClass(ClassName.COLLAPSING)
         .removeClass(ClassName.COLLAPSE)
-        .removeClass(ClassName.IN)
+        .removeClass(ClassName.SHOW)
 
       this._element.setAttribute('aria-expanded', false)
 
@@ -227,7 +233,7 @@ const Collapse = (($) => {
 
       this.setTransitioning(true)
 
-      let complete = () => {
+      const complete = () => {
         this.setTransitioning(false)
         $(this._element)
           .removeClass(ClassName.COLLAPSING)
@@ -235,7 +241,7 @@ const Collapse = (($) => {
           .trigger(Event.HIDDEN)
       }
 
-      this._element.style[dimension] = 0
+      this._element.style[dimension] = ''
 
       if (!Util.supportsTransitionEnd()) {
         complete()
@@ -272,13 +278,13 @@ const Collapse = (($) => {
     }
 
     _getDimension() {
-      let hasWidth = $(this._element).hasClass(Dimension.WIDTH)
+      const hasWidth = $(this._element).hasClass(Dimension.WIDTH)
       return hasWidth ? Dimension.WIDTH : Dimension.HEIGHT
     }
 
     _getParent() {
-      let parent   = $(this._config.parent)[0]
-      let selector =
+      const parent   = $(this._config.parent)[0]
+      const selector =
         `[data-toggle="collapse"][data-parent="${this._config.parent}"]`
 
       $(parent).find(selector).each((i, element) => {
@@ -293,7 +299,7 @@ const Collapse = (($) => {
 
     _addAriaAndCollapsedClass(element, triggerArray) {
       if (element) {
-        let isOpen = $(element).hasClass(ClassName.IN)
+        const isOpen = $(element).hasClass(ClassName.SHOW)
         element.setAttribute('aria-expanded', isOpen)
 
         if (triggerArray.length) {
@@ -308,15 +314,15 @@ const Collapse = (($) => {
     // static
 
     static _getTargetFromElement(element) {
-      let selector = Util.getSelectorFromElement(element)
+      const selector = Util.getSelectorFromElement(element)
       return selector ? $(selector)[0] : null
     }
 
     static _jQueryInterface(config) {
       return this.each(function () {
-        let $this   = $(this)
-        let data    = $this.data(DATA_KEY)
-        let _config = $.extend(
+        const $this   = $(this)
+        let data      = $this.data(DATA_KEY)
+        const _config = $.extend(
           {},
           Default,
           $this.data(),
@@ -353,9 +359,9 @@ const Collapse = (($) => {
   $(document).on(Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
     event.preventDefault()
 
-    let target = Collapse._getTargetFromElement(this)
-    let data   = $(target).data(DATA_KEY)
-    let config = data ? 'toggle' : $(this).data()
+    const target = Collapse._getTargetFromElement(this)
+    const data   = $(target).data(DATA_KEY)
+    const config = data ? 'toggle' : $(this).data()
 
     Collapse._jQueryInterface.call($(target), config)
   })
diff --git a/js/src/dropdown.js b/js/src/dropdown.js
index a9786a534..bcf13caf1 100644
--- a/js/src/dropdown.js
+++ b/js/src/dropdown.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): dropdown.js
+ * Bootstrap (v4.0.0-alpha.5): dropdown.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -17,12 +17,16 @@ const Dropdown = (($) => {
    * ------------------------------------------------------------------------
    */
 
-  const NAME                = 'dropdown'
-  const VERSION             = '4.0.0-alpha.2'
-  const DATA_KEY            = 'bs.dropdown'
-  const EVENT_KEY           = `.${DATA_KEY}`
-  const DATA_API_KEY        = '.data-api'
-  const JQUERY_NO_CONFLICT  = $.fn[NAME]
+  const NAME                     = 'dropdown'
+  const VERSION                  = '4.0.0-alpha.5'
+  const DATA_KEY                 = 'bs.dropdown'
+  const EVENT_KEY                = `.${DATA_KEY}`
+  const DATA_API_KEY             = '.data-api'
+  const JQUERY_NO_CONFLICT       = $.fn[NAME]
+  const ESCAPE_KEYCODE           = 27 // KeyboardEvent.which value for Escape (Esc) key
+  const ARROW_UP_KEYCODE         = 38 // KeyboardEvent.which value for up arrow key
+  const ARROW_DOWN_KEYCODE       = 40 // KeyboardEvent.which value for down arrow key
+  const RIGHT_MOUSE_BUTTON_WHICH = 3 // MouseEvent.which value for the right button (assuming a right-handed mouse)
 
   const Event = {
     HIDE             : `hide${EVENT_KEY}`,
@@ -37,7 +41,7 @@ const Dropdown = (($) => {
   const ClassName = {
     BACKDROP : 'dropdown-backdrop',
     DISABLED : 'disabled',
-    OPEN     : 'open'
+    SHOW     : 'show'
   }
 
   const Selector = {
@@ -79,8 +83,8 @@ const Dropdown = (($) => {
         return false
       }
 
-      let parent   = Dropdown._getParentFromElement(this)
-      let isActive = $(parent).hasClass(ClassName.OPEN)
+      const parent   = Dropdown._getParentFromElement(this)
+      const isActive = $(parent).hasClass(ClassName.SHOW)
 
       Dropdown._clearMenus()
 
@@ -89,17 +93,19 @@ const Dropdown = (($) => {
       }
 
       if ('ontouchstart' in document.documentElement &&
-         (!$(parent).closest(Selector.NAVBAR_NAV).length)) {
+         !$(parent).closest(Selector.NAVBAR_NAV).length) {
 
         // if mobile we use a backdrop because click events don't delegate
-        let dropdown       = document.createElement('div')
+        const dropdown     = document.createElement('div')
         dropdown.className = ClassName.BACKDROP
         $(dropdown).insertBefore(this)
         $(dropdown).on('click', Dropdown._clearMenus)
       }
 
-      let relatedTarget = { relatedTarget : this }
-      let showEvent     = $.Event(Event.SHOW, relatedTarget)
+      const relatedTarget = {
+        relatedTarget : this
+      }
+      const showEvent     = $.Event(Event.SHOW, relatedTarget)
 
       $(parent).trigger(showEvent)
 
@@ -108,9 +114,9 @@ const Dropdown = (($) => {
       }
 
       this.focus()
-      this.setAttribute('aria-expanded', 'true')
+      this.setAttribute('aria-expanded', true)
 
-      $(parent).toggleClass(ClassName.OPEN)
+      $(parent).toggleClass(ClassName.SHOW)
       $(parent).trigger($.Event(Event.SHOWN, relatedTarget))
 
       return false
@@ -134,10 +140,11 @@ const Dropdown = (($) => {
 
     static _jQueryInterface(config) {
       return this.each(function () {
-        let data  = $(this).data(DATA_KEY)
+        let data = $(this).data(DATA_KEY)
 
         if (!data) {
-          $(this).data(DATA_KEY, (data = new Dropdown(this)))
+          data = new Dropdown(this)
+          $(this).data(DATA_KEY, data)
         }
 
         if (typeof config === 'string') {
@@ -150,32 +157,34 @@ const Dropdown = (($) => {
     }
 
     static _clearMenus(event) {
-      if (event && event.which === 3) {
+      if (event && event.which === RIGHT_MOUSE_BUTTON_WHICH) {
         return
       }
 
-      let backdrop = $(Selector.BACKDROP)[0]
+      const backdrop = $(Selector.BACKDROP)[0]
       if (backdrop) {
         backdrop.parentNode.removeChild(backdrop)
       }
 
-      let toggles = $.makeArray($(Selector.DATA_TOGGLE))
+      const toggles = $.makeArray($(Selector.DATA_TOGGLE))
 
       for (let i = 0; i < toggles.length; i++) {
-        let parent        = Dropdown._getParentFromElement(toggles[i])
-        let relatedTarget = { relatedTarget : toggles[i] }
+        const parent        = Dropdown._getParentFromElement(toggles[i])
+        const relatedTarget = {
+          relatedTarget : toggles[i]
+        }
 
-        if (!$(parent).hasClass(ClassName.OPEN)) {
+        if (!$(parent).hasClass(ClassName.SHOW)) {
           continue
         }
 
         if (event && event.type === 'click' &&
-           (/input|textarea/i.test(event.target.tagName)) &&
-           ($.contains(parent, event.target))) {
+           /input|textarea/i.test(event.target.tagName) &&
+           $.contains(parent, event.target)) {
           continue
         }
 
-        let hideEvent = $.Event(Event.HIDE, relatedTarget)
+        const hideEvent = $.Event(Event.HIDE, relatedTarget)
         $(parent).trigger(hideEvent)
         if (hideEvent.isDefaultPrevented()) {
           continue
@@ -184,14 +193,14 @@ const Dropdown = (($) => {
         toggles[i].setAttribute('aria-expanded', 'false')
 
         $(parent)
-          .removeClass(ClassName.OPEN)
+          .removeClass(ClassName.SHOW)
           .trigger($.Event(Event.HIDDEN, relatedTarget))
       }
     }
 
     static _getParentFromElement(element) {
       let parent
-      let selector = Util.getSelectorFromElement(element)
+      const selector = Util.getSelectorFromElement(element)
 
       if (selector) {
         parent = $(selector)[0]
@@ -213,14 +222,14 @@ const Dropdown = (($) => {
         return
       }
 
-      let parent   = Dropdown._getParentFromElement(this)
-      let isActive = $(parent).hasClass(ClassName.OPEN)
+      const parent   = Dropdown._getParentFromElement(this)
+      const isActive = $(parent).hasClass(ClassName.SHOW)
 
-      if ((!isActive && event.which !== 27) ||
-           (isActive && event.which === 27)) {
+      if (!isActive && event.which !== ESCAPE_KEYCODE ||
+           isActive && event.which === ESCAPE_KEYCODE) {
 
-        if (event.which === 27) {
-          let toggle = $(parent).find(Selector.DATA_TOGGLE)[0]
+        if (event.which === ESCAPE_KEYCODE) {
+          const toggle = $(parent).find(Selector.DATA_TOGGLE)[0]
           $(toggle).trigger('focus')
         }
 
@@ -228,11 +237,7 @@ const Dropdown = (($) => {
         return
       }
 
-      let items = $.makeArray($(Selector.VISIBLE_ITEMS))
-
-      items = items.filter((item) => {
-        return item.offsetWidth || item.offsetHeight
-      })
+      const items = $(parent).find(Selector.VISIBLE_ITEMS).get()
 
       if (!items.length) {
         return
@@ -240,11 +245,11 @@ const Dropdown = (($) => {
 
       let index = items.indexOf(event.target)
 
-      if (event.which === 38 && index > 0) { // up
+      if (event.which === ARROW_UP_KEYCODE && index > 0) { // up
         index--
       }
 
-      if (event.which === 40 && index < items.length - 1) { // down
+      if (event.which === ARROW_DOWN_KEYCODE && index < items.length - 1) { // down
         index++
       }
 
diff --git a/js/src/modal.js b/js/src/modal.js
index f52af09a2..94abd19f4 100644
--- a/js/src/modal.js
+++ b/js/src/modal.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): modal.js
+ * Bootstrap (v4.0.0-alpha.5): modal.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,13 +18,14 @@ const Modal = (($) => {
    */
 
   const NAME                         = 'modal'
-  const VERSION                      = '4.0.0-alpha.2'
+  const VERSION                      = '4.0.0-alpha.5'
   const DATA_KEY                     = 'bs.modal'
   const EVENT_KEY                    = `.${DATA_KEY}`
   const DATA_API_KEY                 = '.data-api'
   const JQUERY_NO_CONFLICT           = $.fn[NAME]
   const TRANSITION_DURATION          = 300
   const BACKDROP_TRANSITION_DURATION = 150
+  const ESCAPE_KEYCODE               = 27 // KeyboardEvent.which value for Escape (Esc) key
 
   const Default = {
     backdrop : true,
@@ -59,7 +60,7 @@ const Modal = (($) => {
     BACKDROP           : 'modal-backdrop',
     OPEN               : 'modal-open',
     FADE               : 'fade',
-    IN                 : 'in'
+    SHOW               : 'show'
   }
 
   const Selector = {
@@ -86,6 +87,7 @@ const Modal = (($) => {
       this._isShown             = false
       this._isBodyOverflowing   = false
       this._ignoreBackdropClick = false
+      this._isTransitioning     = false
       this._originalBodyPadding = 0
       this._scrollbarWidth      = 0
     }
@@ -109,7 +111,15 @@ const Modal = (($) => {
     }
 
     show(relatedTarget) {
-      let showEvent = $.Event(Event.SHOW, {
+      if (this._isTransitioning) {
+        throw new Error('Modal is transitioning')
+      }
+
+      if (Util.supportsTransitionEnd() &&
+        $(this._element).hasClass(ClassName.FADE)) {
+        this._isTransitioning = true
+      }
+      const showEvent = $.Event(Event.SHOW, {
         relatedTarget
       })
 
@@ -132,7 +142,7 @@ const Modal = (($) => {
       $(this._element).on(
         Event.CLICK_DISMISS,
         Selector.DATA_DISMISS,
-        $.proxy(this.hide, this)
+        (event) => this.hide(event)
       )
 
       $(this._dialog).on(Event.MOUSEDOWN_DISMISS, () => {
@@ -143,9 +153,7 @@ const Modal = (($) => {
         })
       })
 
-      this._showBackdrop(
-        $.proxy(this._showElement, this, relatedTarget)
-      )
+      this._showBackdrop(() => this._showElement(relatedTarget))
     }
 
     hide(event) {
@@ -153,8 +161,17 @@ const Modal = (($) => {
         event.preventDefault()
       }
 
-      let hideEvent = $.Event(Event.HIDE)
+      if (this._isTransitioning) {
+        throw new Error('Modal is transitioning')
+      }
 
+      const transition = Util.supportsTransitionEnd() &&
+        $(this._element).hasClass(ClassName.FADE)
+      if (transition) {
+        this._isTransitioning = true
+      }
+
+      const hideEvent = $.Event(Event.HIDE)
       $(this._element).trigger(hideEvent)
 
       if (!this._isShown || hideEvent.isDefaultPrevented()) {
@@ -168,16 +185,14 @@ const Modal = (($) => {
 
       $(document).off(Event.FOCUSIN)
 
-      $(this._element).removeClass(ClassName.IN)
+      $(this._element).removeClass(ClassName.SHOW)
 
       $(this._element).off(Event.CLICK_DISMISS)
       $(this._dialog).off(Event.MOUSEDOWN_DISMISS)
 
-      if (Util.supportsTransitionEnd() &&
-         ($(this._element).hasClass(ClassName.FADE))) {
-
+      if (transition) {
         $(this._element)
-          .one(Util.TRANSITION_END, $.proxy(this._hideModal, this))
+          .one(Util.TRANSITION_END, (event) => this._hideModal(event))
           .emulateTransitionEnd(TRANSITION_DURATION)
       } else {
         this._hideModal()
@@ -187,10 +202,7 @@ const Modal = (($) => {
     dispose() {
       $.removeData(this._element, DATA_KEY)
 
-      $(window).off(EVENT_KEY)
-      $(document).off(EVENT_KEY)
-      $(this._element).off(EVENT_KEY)
-      $(this._backdrop).off(EVENT_KEY)
+      $(window, document, this._element, this._backdrop).off(EVENT_KEY)
 
       this._config              = null
       this._element             = null
@@ -213,11 +225,11 @@ const Modal = (($) => {
     }
 
     _showElement(relatedTarget) {
-      let transition = Util.supportsTransitionEnd() &&
+      const transition = Util.supportsTransitionEnd() &&
         $(this._element).hasClass(ClassName.FADE)
 
       if (!this._element.parentNode ||
-         (this._element.parentNode.nodeType !== Node.ELEMENT_NODE)) {
+         this._element.parentNode.nodeType !== Node.ELEMENT_NODE) {
         // don't move modals dom position
         document.body.appendChild(this._element)
       }
@@ -230,20 +242,21 @@ const Modal = (($) => {
         Util.reflow(this._element)
       }
 
-      $(this._element).addClass(ClassName.IN)
+      $(this._element).addClass(ClassName.SHOW)
 
       if (this._config.focus) {
         this._enforceFocus()
       }
 
-      let shownEvent = $.Event(Event.SHOWN, {
+      const shownEvent = $.Event(Event.SHOWN, {
         relatedTarget
       })
 
-      let transitionComplete = () => {
+      const transitionComplete = () => {
         if (this._config.focus) {
           this._element.focus()
         }
+        this._isTransitioning = false
         $(this._element).trigger(shownEvent)
       }
 
@@ -262,7 +275,7 @@ const Modal = (($) => {
         .on(Event.FOCUSIN, (event) => {
           if (document !== event.target &&
               this._element !== event.target &&
-              (!$(this._element).has(event.target).length)) {
+              !$(this._element).has(event.target).length) {
             this._element.focus()
           }
         })
@@ -271,7 +284,7 @@ const Modal = (($) => {
     _setEscapeEvent() {
       if (this._isShown && this._config.keyboard) {
         $(this._element).on(Event.KEYDOWN_DISMISS, (event) => {
-          if (event.which === 27) {
+          if (event.which === ESCAPE_KEYCODE) {
             this.hide()
           }
         })
@@ -283,7 +296,7 @@ const Modal = (($) => {
 
     _setResizeEvent() {
       if (this._isShown) {
-        $(window).on(Event.RESIZE, $.proxy(this._handleUpdate, this))
+        $(window).on(Event.RESIZE, (event) => this._handleUpdate(event))
       } else {
         $(window).off(Event.RESIZE)
       }
@@ -292,6 +305,7 @@ const Modal = (($) => {
     _hideModal() {
       this._element.style.display = 'none'
       this._element.setAttribute('aria-hidden', 'true')
+      this._isTransitioning = false
       this._showBackdrop(() => {
         $(document.body).removeClass(ClassName.OPEN)
         this._resetAdjustments()
@@ -308,11 +322,11 @@ const Modal = (($) => {
     }
 
     _showBackdrop(callback) {
-      let animate = $(this._element).hasClass(ClassName.FADE) ?
+      const animate = $(this._element).hasClass(ClassName.FADE) ?
         ClassName.FADE : ''
 
       if (this._isShown && this._config.backdrop) {
-        let doAnimate = Util.supportsTransitionEnd() && animate
+        const doAnimate = Util.supportsTransitionEnd() && animate
 
         this._backdrop = document.createElement('div')
         this._backdrop.className = ClassName.BACKDROP
@@ -342,7 +356,7 @@ const Modal = (($) => {
           Util.reflow(this._backdrop)
         }
 
-        $(this._backdrop).addClass(ClassName.IN)
+        $(this._backdrop).addClass(ClassName.SHOW)
 
         if (!callback) {
           return
@@ -358,9 +372,9 @@ const Modal = (($) => {
           .emulateTransitionEnd(BACKDROP_TRANSITION_DURATION)
 
       } else if (!this._isShown && this._backdrop) {
-        $(this._backdrop).removeClass(ClassName.IN)
+        $(this._backdrop).removeClass(ClassName.SHOW)
 
-        let callbackRemove = () => {
+        const callbackRemove = () => {
           this._removeBackdrop()
           if (callback) {
             callback()
@@ -368,7 +382,7 @@ const Modal = (($) => {
         }
 
         if (Util.supportsTransitionEnd() &&
-           ($(this._element).hasClass(ClassName.FADE))) {
+           $(this._element).hasClass(ClassName.FADE)) {
           $(this._backdrop)
             .one(Util.TRANSITION_END, callbackRemove)
             .emulateTransitionEnd(BACKDROP_TRANSITION_DURATION)
@@ -392,7 +406,7 @@ const Modal = (($) => {
     }
 
     _adjustDialog() {
-      let isModalOverflowing =
+      const isModalOverflowing =
         this._element.scrollHeight > document.documentElement.clientHeight
 
       if (!this._isBodyOverflowing && isModalOverflowing) {
@@ -415,7 +429,7 @@ const Modal = (($) => {
     }
 
     _setScrollbar() {
-      let bodyPadding = parseInt(
+      const bodyPadding = parseInt(
         $(Selector.FIXED_CONTENT).css('padding-right') || 0,
         10
       )
@@ -433,10 +447,10 @@ const Modal = (($) => {
     }
 
     _getScrollbarWidth() { // thx d.walsh
-      let scrollDiv = document.createElement('div')
+      const scrollDiv = document.createElement('div')
       scrollDiv.className = ClassName.SCROLLBAR_MEASURER
       document.body.appendChild(scrollDiv)
-      let scrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth
+      const scrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth
       document.body.removeChild(scrollDiv)
       return scrollbarWidth
     }
@@ -446,8 +460,8 @@ const Modal = (($) => {
 
     static _jQueryInterface(config, relatedTarget) {
       return this.each(function () {
-        let data    = $(this).data(DATA_KEY)
-        let _config = $.extend(
+        let data      = $(this).data(DATA_KEY)
+        const _config = $.extend(
           {},
           Modal.Default,
           $(this).data(),
@@ -481,20 +495,20 @@ const Modal = (($) => {
 
   $(document).on(Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
     let target
-    let selector = Util.getSelectorFromElement(this)
+    const selector = Util.getSelectorFromElement(this)
 
     if (selector) {
       target = $(selector)[0]
     }
 
-    let config = $(target).data(DATA_KEY) ?
+    const config = $(target).data(DATA_KEY) ?
       'toggle' : $.extend({}, $(target).data(), $(this).data())
 
-    if (this.tagName === 'A') {
+    if (this.tagName === 'A' || this.tagName === 'AREA') {
       event.preventDefault()
     }
 
-    let $target = $(target).one(Event.SHOW, (showEvent) => {
+    const $target = $(target).one(Event.SHOW, (showEvent) => {
       if (showEvent.isDefaultPrevented()) {
         // only register focus restorer if modal will actually get shown
         return
diff --git a/js/src/popover.js b/js/src/popover.js
index 7e8ec4297..33bc9e48c 100644
--- a/js/src/popover.js
+++ b/js/src/popover.js
@@ -3,7 +3,7 @@ import Tooltip from './tooltip'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): popover.js
+ * Bootstrap (v4.0.0-alpha.5): popover.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,7 +18,7 @@ const Popover = (($) => {
    */
 
   const NAME                = 'popover'
-  const VERSION             = '4.0.0-alpha.2'
+  const VERSION             = '4.0.0-alpha.5'
   const DATA_KEY            = 'bs.popover'
   const EVENT_KEY           = `.${DATA_KEY}`
   const JQUERY_NO_CONFLICT  = $.fn[NAME]
@@ -28,7 +28,6 @@ const Popover = (($) => {
     trigger   : 'click',
     content   : '',
     template  : '<div class="popover" role="tooltip">'
-              + '<div class="popover-arrow"></div>'
               + '<h3 class="popover-title"></h3>'
               + '<div class="popover-content"></div></div>'
   })
@@ -39,13 +38,12 @@ const Popover = (($) => {
 
   const ClassName = {
     FADE : 'fade',
-    IN  : 'in'
+    SHOW : 'show'
   }
 
   const Selector = {
     TITLE   : '.popover-title',
-    CONTENT : '.popover-content',
-    ARROW   : '.popover-arrow'
+    CONTENT : '.popover-content'
   }
 
   const Event = {
@@ -109,19 +107,17 @@ const Popover = (($) => {
     }
 
     getTipElement() {
-      return (this.tip = this.tip || $(this.config.template)[0])
+      return this.tip = this.tip || $(this.config.template)[0]
     }
 
     setContent() {
-      let $tip = $(this.getTipElement())
+      const $tip = $(this.getTipElement())
 
       // we use append for html objects to maintain js events
       this.setElementContent($tip.find(Selector.TITLE), this.getTitle())
       this.setElementContent($tip.find(Selector.CONTENT), this._getContent())
 
-      $tip
-        .removeClass(ClassName.FADE)
-        .removeClass(ClassName.IN)
+      $tip.removeClass(`${ClassName.FADE} ${ClassName.SHOW}`)
 
       this.cleanupTether()
     }
@@ -140,8 +136,8 @@ const Popover = (($) => {
 
     static _jQueryInterface(config) {
       return this.each(function () {
-        let data   = $(this).data(DATA_KEY)
-        let _config = typeof config === 'object' ? config : null
+        let data      = $(this).data(DATA_KEY)
+        const _config = typeof config === 'object' ? config : null
 
         if (!data && /destroy|hide/.test(config)) {
           return
diff --git a/js/src/scrollspy.js b/js/src/scrollspy.js
index b9186db00..0a4708bf9 100644
--- a/js/src/scrollspy.js
+++ b/js/src/scrollspy.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): scrollspy.js
+ * Bootstrap (v4.0.0-alpha.5): scrollspy.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,7 +18,7 @@ const ScrollSpy = (($) => {
    */
 
   const NAME               = 'scrollspy'
-  const VERSION            = '4.0.0-alpha.2'
+  const VERSION            = '4.0.0-alpha.5'
   const DATA_KEY           = 'bs.scrollspy'
   const EVENT_KEY          = `.${DATA_KEY}`
   const DATA_API_KEY       = '.data-api'
@@ -87,7 +87,7 @@ const ScrollSpy = (($) => {
       this._activeTarget  = null
       this._scrollHeight  = 0
 
-      $(this._scrollElement).on(Event.SCROLL, $.proxy(this._process, this))
+      $(this._scrollElement).on(Event.SCROLL, (event) => this._process(event))
 
       this.refresh()
       this._process()
@@ -108,13 +108,13 @@ const ScrollSpy = (($) => {
     // public
 
     refresh() {
-      let autoMethod = this._scrollElement !== this._scrollElement.window ?
+      const autoMethod = this._scrollElement !== this._scrollElement.window ?
         OffsetMethod.POSITION : OffsetMethod.OFFSET
 
-      let offsetMethod = this._config.method === 'auto' ?
+      const offsetMethod = this._config.method === 'auto' ?
         autoMethod : this._config.method
 
-      let offsetBase = offsetMethod === OffsetMethod.POSITION ?
+      const offsetBase = offsetMethod === OffsetMethod.POSITION ?
         this._getScrollTop() : 0
 
       this._offsets = []
@@ -122,12 +122,12 @@ const ScrollSpy = (($) => {
 
       this._scrollHeight = this._getScrollHeight()
 
-      let targets = $.makeArray($(this._selector))
+      const targets = $.makeArray($(this._selector))
 
       targets
         .map((element) => {
           let target
-          let targetSelector = Util.getSelectorFromElement(element)
+          const targetSelector = Util.getSelectorFromElement(element)
 
           if (targetSelector) {
             target = $(targetSelector)[0]
@@ -140,6 +140,7 @@ const ScrollSpy = (($) => {
               targetSelector
             ]
           }
+          return null
         })
         .filter((item)  => item)
         .sort((a, b)    => a[0] - b[0])
@@ -195,33 +196,39 @@ const ScrollSpy = (($) => {
       )
     }
 
+    _getOffsetHeight() {
+      return this._scrollElement === window ?
+          window.innerHeight : this._scrollElement.offsetHeight
+    }
+
     _process() {
-      let scrollTop    = this._getScrollTop() + this._config.offset
-      let scrollHeight = this._getScrollHeight()
-      let maxScroll    = this._config.offset
+      const scrollTop    = this._getScrollTop() + this._config.offset
+      const scrollHeight = this._getScrollHeight()
+      const maxScroll    = this._config.offset
         + scrollHeight
-        - this._scrollElement.offsetHeight
+        - this._getOffsetHeight()
 
       if (this._scrollHeight !== scrollHeight) {
         this.refresh()
       }
 
       if (scrollTop >= maxScroll) {
-        let target = this._targets[this._targets.length - 1]
+        const target = this._targets[this._targets.length - 1]
 
         if (this._activeTarget !== target) {
           this._activate(target)
         }
+        return
       }
 
-      if (this._activeTarget && scrollTop < this._offsets[0]) {
+      if (this._activeTarget && scrollTop < this._offsets[0] && this._offsets[0] > 0) {
         this._activeTarget = null
         this._clear()
         return
       }
 
       for (let i = this._offsets.length; i--;) {
-        let isActiveTarget = this._activeTarget !== this._targets[i]
+        const isActiveTarget = this._activeTarget !== this._targets[i]
             && scrollTop >= this._offsets[i]
             && (this._offsets[i + 1] === undefined ||
                 scrollTop < this._offsets[i + 1])
@@ -243,7 +250,7 @@ const ScrollSpy = (($) => {
                `${selector}[href="${target}"]`
       })
 
-      let $link = $(queries.join(','))
+      const $link = $(queries.join(','))
 
       if ($link.hasClass(ClassName.DROPDOWN_ITEM)) {
         $link.closest(Selector.DROPDOWN).find(Selector.DROPDOWN_TOGGLE).addClass(ClassName.ACTIVE)
@@ -251,7 +258,7 @@ const ScrollSpy = (($) => {
       } else {
         // todo (fat) this is kinda sus...
         // recursively add actives to tested nav-links
-        $link.parents(Selector.LI).find(Selector.NAV_LINKS).addClass(ClassName.ACTIVE)
+        $link.parents(Selector.LI).find(`> ${Selector.NAV_LINKS}`).addClass(ClassName.ACTIVE)
       }
 
       $(this._scrollElement).trigger(Event.ACTIVATE, {
@@ -268,8 +275,8 @@ const ScrollSpy = (($) => {
 
     static _jQueryInterface(config) {
       return this.each(function () {
-        let data    = $(this).data(DATA_KEY)
-        let _config = typeof config === 'object' && config || null
+        let data      = $(this).data(DATA_KEY)
+        const _config = typeof config === 'object' && config
 
         if (!data) {
           data = new ScrollSpy(this, _config)
@@ -296,10 +303,10 @@ const ScrollSpy = (($) => {
    */
 
   $(window).on(Event.LOAD_DATA_API, () => {
-    let scrollSpys = $.makeArray($(Selector.DATA_SPY))
+    const scrollSpys = $.makeArray($(Selector.DATA_SPY))
 
     for (let i = scrollSpys.length; i--;) {
-      let $spy = $(scrollSpys[i])
+      const $spy = $(scrollSpys[i])
       ScrollSpy._jQueryInterface.call($spy, $spy.data())
     }
   })
diff --git a/js/src/tab.js b/js/src/tab.js
index 33f56faae..2f4e453e0 100644
--- a/js/src/tab.js
+++ b/js/src/tab.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): tab.js
+ * Bootstrap (v4.0.0-alpha.5): tab.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,7 +18,7 @@ const Tab = (($) => {
    */
 
   const NAME                = 'tab'
-  const VERSION             = '4.0.0-alpha.2'
+  const VERSION             = '4.0.0-alpha.5'
   const DATA_KEY            = 'bs.tab'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
@@ -36,15 +36,16 @@ const Tab = (($) => {
   const ClassName = {
     DROPDOWN_MENU : 'dropdown-menu',
     ACTIVE        : 'active',
+    DISABLED      : 'disabled',
     FADE          : 'fade',
-    IN            : 'in'
+    SHOW          : 'show'
   }
 
   const Selector = {
     A                     : 'a',
     LI                    : 'li',
     DROPDOWN              : '.dropdown',
-    UL                    : 'ul:not(.dropdown-menu)',
+    LIST                  : 'ul:not(.dropdown-menu), ol:not(.dropdown-menu)',
     FADE_CHILD            : '> .nav-item .fade, > .fade',
     ACTIVE                : '.active',
     ACTIVE_CHILD          : '> .nav-item > .active, > .active',
@@ -78,26 +79,27 @@ const Tab = (($) => {
 
     show() {
       if (this._element.parentNode &&
-         (this._element.parentNode.nodeType === Node.ELEMENT_NODE) &&
-         ($(this._element).hasClass(ClassName.ACTIVE))) {
+          this._element.parentNode.nodeType === Node.ELEMENT_NODE &&
+          $(this._element).hasClass(ClassName.ACTIVE) ||
+          $(this._element).hasClass(ClassName.DISABLED)) {
         return
       }
 
       let target
       let previous
-      let ulElement = $(this._element).closest(Selector.UL)[0]
-      let selector  = Util.getSelectorFromElement(this._element)
+      const listElement = $(this._element).closest(Selector.LIST)[0]
+      const selector    = Util.getSelectorFromElement(this._element)
 
-      if (ulElement) {
-        previous = $.makeArray($(ulElement).find(Selector.ACTIVE))
+      if (listElement) {
+        previous = $.makeArray($(listElement).find(Selector.ACTIVE))
         previous = previous[previous.length - 1]
       }
 
-      let hideEvent = $.Event(Event.HIDE, {
+      const hideEvent = $.Event(Event.HIDE, {
         relatedTarget: this._element
       })
 
-      let showEvent = $.Event(Event.SHOW, {
+      const showEvent = $.Event(Event.SHOW, {
         relatedTarget: previous
       })
 
@@ -108,7 +110,7 @@ const Tab = (($) => {
       $(this._element).trigger(showEvent)
 
       if (showEvent.isDefaultPrevented() ||
-         (hideEvent.isDefaultPrevented())) {
+         hideEvent.isDefaultPrevented()) {
         return
       }
 
@@ -118,15 +120,15 @@ const Tab = (($) => {
 
       this._activate(
         this._element,
-        ulElement
+        listElement
       )
 
-      let complete = () => {
-        let hiddenEvent = $.Event(Event.HIDDEN, {
+      const complete = () => {
+        const hiddenEvent = $.Event(Event.HIDDEN, {
           relatedTarget: this._element
         })
 
-        let shownEvent  = $.Event(Event.SHOWN, {
+        const shownEvent = $.Event(Event.SHOWN, {
           relatedTarget: previous
         })
 
@@ -150,15 +152,13 @@ const Tab = (($) => {
     // private
 
     _activate(element, container, callback) {
-      let active          = $(container).find(Selector.ACTIVE_CHILD)[0]
-      let isTransitioning = callback
+      const active          = $(container).find(Selector.ACTIVE_CHILD)[0]
+      const isTransitioning = callback
         && Util.supportsTransitionEnd()
-        && ((active && $(active).hasClass(ClassName.FADE))
+        && (active && $(active).hasClass(ClassName.FADE)
            || Boolean($(container).find(Selector.FADE_CHILD)[0]))
 
-      let complete = $.proxy(
-        this._transitionComplete,
-        this,
+      const complete = () => this._transitionComplete(
         element,
         active,
         isTransitioning,
@@ -175,7 +175,7 @@ const Tab = (($) => {
       }
 
       if (active) {
-        $(active).removeClass(ClassName.IN)
+        $(active).removeClass(ClassName.SHOW)
       }
     }
 
@@ -183,7 +183,7 @@ const Tab = (($) => {
       if (active) {
         $(active).removeClass(ClassName.ACTIVE)
 
-        let dropdownChild = $(active).find(
+        const dropdownChild = $(active.parentNode).find(
           Selector.DROPDOWN_ACTIVE_CHILD
         )[0]
 
@@ -199,15 +199,15 @@ const Tab = (($) => {
 
       if (isTransitioning) {
         Util.reflow(element)
-        $(element).addClass(ClassName.IN)
+        $(element).addClass(ClassName.SHOW)
       } else {
         $(element).removeClass(ClassName.FADE)
       }
 
       if (element.parentNode &&
-         ($(element.parentNode).hasClass(ClassName.DROPDOWN_MENU))) {
+          $(element.parentNode).hasClass(ClassName.DROPDOWN_MENU)) {
 
-        let dropdownElement = $(element).closest(Selector.DROPDOWN)[0]
+        const dropdownElement = $(element).closest(Selector.DROPDOWN)[0]
         if (dropdownElement) {
           $(dropdownElement).find(Selector.DROPDOWN_TOGGLE).addClass(ClassName.ACTIVE)
         }
@@ -225,11 +225,11 @@ const Tab = (($) => {
 
     static _jQueryInterface(config) {
       return this.each(function () {
-        let $this = $(this)
-        let data  = $this.data(DATA_KEY)
+        const $this = $(this)
+        let data    = $this.data(DATA_KEY)
 
         if (!data) {
-          data = data = new Tab(this)
+          data = new Tab(this)
           $this.data(DATA_KEY, data)
         }
 
diff --git a/js/src/tooltip.js b/js/src/tooltip.js
index 77803dc40..0c1d381b9 100644
--- a/js/src/tooltip.js
+++ b/js/src/tooltip.js
@@ -5,7 +5,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): tooltip.js
+ * Bootstrap (v4.0.0-alpha.5): tooltip.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -14,10 +14,10 @@ const Tooltip = (($) => {
 
   /**
    * Check for Tether dependency
-   * Tether - http://github.hubspot.com/tether/
+   * Tether - http://tether.io/
    */
-  if (window.Tether === undefined) {
-    throw new Error('Bootstrap tooltips require Tether (http://github.hubspot.com/tether/)')
+  if (typeof Tether === 'undefined') {
+    throw new Error('Bootstrap tooltips require Tether (http://tether.io/)')
   }
 
 
@@ -28,7 +28,7 @@ const Tooltip = (($) => {
    */
 
   const NAME                = 'tooltip'
-  const VERSION             = '4.0.0-alpha.2'
+  const VERSION             = '4.0.0-alpha.5'
   const DATA_KEY            = 'bs.tooltip'
   const EVENT_KEY           = `.${DATA_KEY}`
   const JQUERY_NO_CONFLICT  = $.fn[NAME]
@@ -38,7 +38,6 @@ const Tooltip = (($) => {
   const Default = {
     animation   : true,
     template    : '<div class="tooltip" role="tooltip">'
-                + '<div class="tooltip-arrow"></div>'
                 + '<div class="tooltip-inner"></div></div>',
     trigger     : 'hover focus',
     title       : '',
@@ -47,7 +46,8 @@ const Tooltip = (($) => {
     selector    : false,
     placement   : 'top',
     offset      : '0 0',
-    constraints : []
+    constraints : [],
+    container   : false
   }
 
   const DefaultType = {
@@ -60,7 +60,8 @@ const Tooltip = (($) => {
     selector    : '(string|boolean)',
     placement   : '(string|function)',
     offset      : 'string',
-    constraints : 'array'
+    constraints : 'array',
+    container   : '(string|element|boolean)'
   }
 
   const AttachmentMap = {
@@ -71,8 +72,8 @@ const Tooltip = (($) => {
   }
 
   const HoverState = {
-    IN  : 'in',
-    OUT : 'out'
+    SHOW : 'show',
+    OUT  : 'out'
   }
 
   const Event = {
@@ -90,7 +91,7 @@ const Tooltip = (($) => {
 
   const ClassName = {
     FADE : 'fade',
-    IN   : 'in'
+    SHOW : 'show'
   }
 
   const Selector = {
@@ -122,11 +123,12 @@ const Tooltip = (($) => {
     constructor(element, config) {
 
       // private
-      this._isEnabled      = true
-      this._timeout        = 0
-      this._hoverState     = ''
-      this._activeTrigger  = {}
-      this._tether         = null
+      this._isEnabled        = true
+      this._timeout          = 0
+      this._hoverState       = ''
+      this._activeTrigger    = {}
+      this._isTransitioning  = false
+      this._tether           = null
 
       // protected
       this.element = element
@@ -185,7 +187,7 @@ const Tooltip = (($) => {
 
     toggle(event) {
       if (event) {
-        let dataKey = this.constructor.DATA_KEY
+        const dataKey = this.constructor.DATA_KEY
         let context = $(event.currentTarget).data(dataKey)
 
         if (!context) {
@@ -206,7 +208,7 @@ const Tooltip = (($) => {
 
       } else {
 
-        if ($(this.getTipElement()).hasClass(ClassName.IN)) {
+        if ($(this.getTipElement()).hasClass(ClassName.SHOW)) {
           this._leave(null, this)
           return
         }
@@ -223,16 +225,17 @@ const Tooltip = (($) => {
       $.removeData(this.element, this.constructor.DATA_KEY)
 
       $(this.element).off(this.constructor.EVENT_KEY)
+      $(this.element).closest('.modal').off('hide.bs.modal')
 
       if (this.tip) {
         $(this.tip).remove()
       }
 
-      this._isEnabled      = null
-      this._timeout        = null
-      this._hoverState     = null
-      this._activeTrigger  = null
-      this._tether         = null
+      this._isEnabled     = null
+      this._timeout       = null
+      this._hoverState    = null
+      this._activeTrigger = null
+      this._tether        = null
 
       this.element = null
       this.config  = null
@@ -240,12 +243,18 @@ const Tooltip = (($) => {
     }
 
     show() {
-      let showEvent = $.Event(this.constructor.Event.SHOW)
+      if ($(this.element).css('display') === 'none') {
+        throw new Error('Please use show on visible elements')
+      }
 
+      const showEvent = $.Event(this.constructor.Event.SHOW)
       if (this.isWithContent() && this._isEnabled) {
+        if (this._isTransitioning) {
+          throw new Error('Tooltip is transitioning')
+        }
         $(this.element).trigger(showEvent)
 
-        let isInTheDom = $.contains(
+        const isInTheDom = $.contains(
           this.element.ownerDocument.documentElement,
           this.element
         )
@@ -254,8 +263,8 @@ const Tooltip = (($) => {
           return
         }
 
-        let tip   = this.getTipElement()
-        let tipId = Util.getUID(this.constructor.NAME)
+        const tip   = this.getTipElement()
+        const tipId = Util.getUID(this.constructor.NAME)
 
         tip.setAttribute('id', tipId)
         this.element.setAttribute('aria-describedby', tipId)
@@ -266,15 +275,17 @@ const Tooltip = (($) => {
           $(tip).addClass(ClassName.FADE)
         }
 
-        let placement  = typeof this.config.placement === 'function' ?
+        const placement  = typeof this.config.placement === 'function' ?
           this.config.placement.call(this, tip, this.element) :
           this.config.placement
 
-        let attachment = this._getAttachment(placement)
+        const attachment = this._getAttachment(placement)
+
+        const container = this.config.container === false ? document.body : $(this.config.container)
 
         $(tip)
           .data(this.constructor.DATA_KEY, this)
-          .appendTo(document.body)
+          .appendTo(container)
 
         $(this.element).trigger(this.constructor.Event.INSERTED)
 
@@ -292,11 +303,12 @@ const Tooltip = (($) => {
         Util.reflow(tip)
         this._tether.position()
 
-        $(tip).addClass(ClassName.IN)
+        $(tip).addClass(ClassName.SHOW)
 
-        let complete = () => {
-          let prevHoverState = this._hoverState
+        const complete = () => {
+          const prevHoverState = this._hoverState
           this._hoverState   = null
+          this._isTransitioning = false
 
           $(this.element).trigger(this.constructor.Event.SHOWN)
 
@@ -306,6 +318,7 @@ const Tooltip = (($) => {
         }
 
         if (Util.supportsTransitionEnd() && $(this.tip).hasClass(ClassName.FADE)) {
+          this._isTransitioning = true
           $(this.tip)
             .one(Util.TRANSITION_END, complete)
             .emulateTransitionEnd(Tooltip._TRANSITION_DURATION)
@@ -317,15 +330,19 @@ const Tooltip = (($) => {
     }
 
     hide(callback) {
-      let tip       = this.getTipElement()
-      let hideEvent = $.Event(this.constructor.Event.HIDE)
-      let complete  = () => {
-        if (this._hoverState !== HoverState.IN && tip.parentNode) {
+      const tip       = this.getTipElement()
+      const hideEvent = $.Event(this.constructor.Event.HIDE)
+      if (this._isTransitioning) {
+        throw new Error('Tooltip is transitioning')
+      }
+      const complete  = () => {
+        if (this._hoverState !== HoverState.SHOW && tip.parentNode) {
           tip.parentNode.removeChild(tip)
         }
 
         this.element.removeAttribute('aria-describedby')
         $(this.element).trigger(this.constructor.Event.HIDDEN)
+        this._isTransitioning = false
         this.cleanupTether()
 
         if (callback) {
@@ -339,11 +356,15 @@ const Tooltip = (($) => {
         return
       }
 
-      $(tip).removeClass(ClassName.IN)
+      $(tip).removeClass(ClassName.SHOW)
 
-      if (Util.supportsTransitionEnd() &&
-         ($(this.tip).hasClass(ClassName.FADE))) {
+      this._activeTrigger[Trigger.CLICK] = false
+      this._activeTrigger[Trigger.FOCUS] = false
+      this._activeTrigger[Trigger.HOVER] = false
 
+      if (Util.supportsTransitionEnd() &&
+          $(this.tip).hasClass(ClassName.FADE)) {
+        this._isTransitioning = true
         $(tip)
           .one(Util.TRANSITION_END, complete)
           .emulateTransitionEnd(TRANSITION_DURATION)
@@ -363,23 +384,21 @@ const Tooltip = (($) => {
     }
 
     getTipElement() {
-      return (this.tip = this.tip || $(this.config.template)[0])
+      return this.tip = this.tip || $(this.config.template)[0]
     }
 
     setContent() {
-      let $tip = $(this.getTipElement())
+      const $tip = $(this.getTipElement())
 
       this.setElementContent($tip.find(Selector.TOOLTIP_INNER), this.getTitle())
 
-      $tip
-        .removeClass(ClassName.FADE)
-        .removeClass(ClassName.IN)
+      $tip.removeClass(`${ClassName.FADE} ${ClassName.SHOW}`)
 
       this.cleanupTether()
     }
 
     setElementContent($element, content) {
-      let html = this.config.html
+      const html = this.config.html
       if (typeof content === 'object' && (content.nodeType || content.jquery)) {
         // content is a DOM node or a jQuery
         if (html) {
@@ -420,21 +439,21 @@ const Tooltip = (($) => {
     }
 
     _setListeners() {
-      let triggers = this.config.trigger.split(' ')
+      const triggers = this.config.trigger.split(' ')
 
       triggers.forEach((trigger) => {
         if (trigger === 'click') {
           $(this.element).on(
             this.constructor.Event.CLICK,
             this.config.selector,
-            $.proxy(this.toggle, this)
+            (event) => this.toggle(event)
           )
 
         } else if (trigger !== Trigger.MANUAL) {
-          let eventIn  = trigger === Trigger.HOVER ?
+          const eventIn  = trigger === Trigger.HOVER ?
             this.constructor.Event.MOUSEENTER :
             this.constructor.Event.FOCUSIN
-          let eventOut = trigger === Trigger.HOVER ?
+          const eventOut = trigger === Trigger.HOVER ?
             this.constructor.Event.MOUSELEAVE :
             this.constructor.Event.FOCUSOUT
 
@@ -442,14 +461,19 @@ const Tooltip = (($) => {
             .on(
               eventIn,
               this.config.selector,
-              $.proxy(this._enter, this)
+              (event) => this._enter(event)
             )
             .on(
               eventOut,
               this.config.selector,
-              $.proxy(this._leave, this)
+              (event) => this._leave(event)
             )
         }
+
+        $(this.element).closest('.modal').on(
+          'hide.bs.modal',
+          () => this.hide()
+        )
       })
 
       if (this.config.selector) {
@@ -463,9 +487,9 @@ const Tooltip = (($) => {
     }
 
     _fixTitle() {
-      let titleType = typeof this.element.getAttribute('data-original-title')
+      const titleType = typeof this.element.getAttribute('data-original-title')
       if (this.element.getAttribute('title') ||
-         (titleType !== 'string')) {
+         titleType !== 'string') {
         this.element.setAttribute(
           'data-original-title',
           this.element.getAttribute('title') || ''
@@ -475,7 +499,7 @@ const Tooltip = (($) => {
     }
 
     _enter(event, context) {
-      let dataKey = this.constructor.DATA_KEY
+      const dataKey = this.constructor.DATA_KEY
 
       context = context || $(event.currentTarget).data(dataKey)
 
@@ -493,15 +517,15 @@ const Tooltip = (($) => {
         ] = true
       }
 
-      if ($(context.getTipElement()).hasClass(ClassName.IN) ||
-         (context._hoverState === HoverState.IN)) {
-        context._hoverState = HoverState.IN
+      if ($(context.getTipElement()).hasClass(ClassName.SHOW) ||
+         context._hoverState === HoverState.SHOW) {
+        context._hoverState = HoverState.SHOW
         return
       }
 
       clearTimeout(context._timeout)
 
-      context._hoverState = HoverState.IN
+      context._hoverState = HoverState.SHOW
 
       if (!context.config.delay || !context.config.delay.show) {
         context.show()
@@ -509,14 +533,14 @@ const Tooltip = (($) => {
       }
 
       context._timeout = setTimeout(() => {
-        if (context._hoverState === HoverState.IN) {
+        if (context._hoverState === HoverState.SHOW) {
           context.show()
         }
       }, context.config.delay.show)
     }
 
     _leave(event, context) {
-      let dataKey = this.constructor.DATA_KEY
+      const dataKey = this.constructor.DATA_KEY
 
       context = context || $(event.currentTarget).data(dataKey)
 
@@ -555,7 +579,7 @@ const Tooltip = (($) => {
     }
 
     _isWithActiveTrigger() {
-      for (let trigger in this._activeTrigger) {
+      for (const trigger in this._activeTrigger) {
         if (this._activeTrigger[trigger]) {
           return true
         }
@@ -589,10 +613,10 @@ const Tooltip = (($) => {
     }
 
     _getDelegateConfig() {
-      let config = {}
+      const config = {}
 
       if (this.config) {
-        for (let key in this.config) {
+        for (const key in this.config) {
           if (this.constructor.Default[key] !== this.config[key]) {
             config[key] = this.config[key]
           }
@@ -607,11 +631,10 @@ const Tooltip = (($) => {
 
     static _jQueryInterface(config) {
       return this.each(function () {
-        let data   = $(this).data(DATA_KEY)
-        let _config = typeof config === 'object' ?
-          config : null
+        let data      = $(this).data(DATA_KEY)
+        const _config = typeof config === 'object' && config
 
-        if (!data && /destroy|hide/.test(config)) {
+        if (!data && /dispose|hide/.test(config)) {
           return
         }
 
diff --git a/js/src/util.js b/js/src/util.js
index dba6e9bd6..06424fbfe 100644
--- a/js/src/util.js
+++ b/js/src/util.js
@@ -1,6 +1,6 @@
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.2): util.js
+ * Bootstrap (v4.0.0-alpha.5): util.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -16,6 +16,8 @@ const Util = (($) => {
 
   let transition = false
 
+  const MAX_UID = 1000000
+
   const TransitionEndEvent = {
     WebkitTransition : 'webkitTransitionEnd',
     MozTransition    : 'transitionend',
@@ -25,7 +27,7 @@ const Util = (($) => {
 
   // shoutout AngusCroll (https://goo.gl/pxwQGp)
   function toType(obj) {
-    return ({}).toString.call(obj).match(/\s([a-zA-Z]+)/)[1].toLowerCase()
+    return {}.toString.call(obj).match(/\s([a-zA-Z]+)/)[1].toLowerCase()
   }
 
   function isElement(obj) {
@@ -38,8 +40,9 @@ const Util = (($) => {
       delegateType: transition.end,
       handle(event) {
         if ($(event.target).is(this)) {
-          return event.handleObj.handler.apply(this, arguments)
+          return event.handleObj.handler.apply(this, arguments) // eslint-disable-line prefer-rest-params
         }
+        return undefined
       }
     }
   }
@@ -49,11 +52,13 @@ const Util = (($) => {
       return false
     }
 
-    let el = document.createElement('bootstrap')
+    const el = document.createElement('bootstrap')
 
-    for (let name in TransitionEndEvent) {
+    for (const name in TransitionEndEvent) {
       if (el.style[name] !== undefined) {
-        return { end: TransitionEndEvent[name] }
+        return {
+          end: TransitionEndEvent[name]
+        }
       }
     }
 
@@ -93,15 +98,14 @@ const Util = (($) => {
    * --------------------------------------------------------------------------
    */
 
-  let Util = {
+  const Util = {
 
     TRANSITION_END: 'bsTransitionEnd',
 
     getUID(prefix) {
       do {
-        /* eslint-disable no-bitwise */
-        prefix += ~~(Math.random() * 1000000) // "~~" acts like a faster Math.floor() here
-        /* eslint-enable no-bitwise */
+        // eslint-disable-next-line no-bitwise
+        prefix += ~~(Math.random() * MAX_UID) // "~~" acts like a faster Math.floor() here
       } while (document.getElementById(prefix))
       return prefix
     },
@@ -118,7 +122,7 @@ const Util = (($) => {
     },
 
     reflow(element) {
-      new Function('bs', 'return bs')(element.offsetHeight)
+      return element.offsetHeight
     },
 
     triggerTransitionEnd(element) {
@@ -130,17 +134,12 @@ const Util = (($) => {
     },
 
     typeCheckConfig(componentName, config, configTypes) {
-      for (let property in configTypes) {
+      for (const property in configTypes) {
         if (configTypes.hasOwnProperty(property)) {
-          let expectedTypes = configTypes[property]
-          let value         = config[property]
-          let valueType
-
-          if (value && isElement(value)) {
-            valueType = 'element'
-          } else {
-            valueType = toType(value)
-          }
+          const expectedTypes = configTypes[property]
+          const value         = config[property]
+          const valueType     = value && isElement(value) ?
+                                'element' : toType(value)
 
           if (!new RegExp(expectedTypes).test(valueType)) {
             throw new Error(