Merge branch 'v4-dev' into v4-docs-streamlined

11 files changed, 520 insertions, 266 deletions

diff --git a/js/src/alert.js b/js/src/alert.js
index 884a5dec8..b30d0d3a0 100644
--- a/js/src/alert.js
+++ b/js/src/alert.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): alert.js
+ * Bootstrap (v4.0.0-alpha.6): 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.5'
+  const VERSION             = '4.0.0-alpha.6'
   const DATA_KEY            = 'bs.alert'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
diff --git a/js/src/button.js b/js/src/button.js
index 45e1424ff..722fd489d 100644
--- a/js/src/button.js
+++ b/js/src/button.js
@@ -1,6 +1,6 @@
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): button.js
+ * Bootstrap (v4.0.0-alpha.6): button.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -15,7 +15,7 @@ const Button = (($) => {
    */
 
   const NAME                = 'button'
-  const VERSION             = '4.0.0-alpha.5'
+  const VERSION             = '4.0.0-alpha.6'
   const DATA_KEY            = 'bs.button'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
@@ -66,6 +66,7 @@ const Button = (($) => {
 
     toggle() {
       let triggerChangeEvent = true
+      let addAriaPressed = true
       const rootElement      = $(this._element).closest(
         Selector.DATA_TOGGLE
       )[0]
@@ -89,14 +90,23 @@ const Button = (($) => {
           }
 
           if (triggerChangeEvent) {
+            if (input.hasAttribute('disabled') ||
+              rootElement.hasAttribute('disabled') ||
+              input.classList.contains('disabled') ||
+              rootElement.classList.contains('disabled')) {
+              return
+            }
             input.checked = !$(this._element).hasClass(ClassName.ACTIVE)
             $(input).trigger('change')
           }
 
           input.focus()
+          addAriaPressed = false
         }
 
-      } else {
+      }
+
+      if (addAriaPressed) {
         this._element.setAttribute('aria-pressed',
           !$(this._element).hasClass(ClassName.ACTIVE))
       }
diff --git a/js/src/carousel.js b/js/src/carousel.js
index 9a1a668b2..5993de256 100644
--- a/js/src/carousel.js
+++ b/js/src/carousel.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): carousel.js
+ * Bootstrap (v4.0.0-alpha.6): carousel.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -17,15 +17,16 @@ const Carousel = (($) => {
    * ------------------------------------------------------------------------
    */
 
-  const NAME                = 'carousel'
-  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  = $.fn[NAME]
-  const TRANSITION_DURATION = 600
-  const ARROW_LEFT_KEYCODE  = 37 // KeyboardEvent.which value for left arrow key
-  const ARROW_RIGHT_KEYCODE = 39 // KeyboardEvent.which value for right arrow key
+  const NAME                   = 'carousel'
+  const VERSION                = '4.0.0-alpha.6'
+  const DATA_KEY               = 'bs.carousel'
+  const EVENT_KEY              = `.${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 TOUCHEVENT_COMPAT_WAIT = 500 // Time for mouse compat events to fire after touch
 
   const Default = {
     interval : 5000,
@@ -56,6 +57,7 @@ const Carousel = (($) => {
     KEYDOWN        : `keydown${EVENT_KEY}`,
     MOUSEENTER     : `mouseenter${EVENT_KEY}`,
     MOUSELEAVE     : `mouseleave${EVENT_KEY}`,
+    TOUCHEND       : `touchend${EVENT_KEY}`,
     LOAD_DATA_API  : `load${EVENT_KEY}${DATA_API_KEY}`,
     CLICK_DATA_API : `click${EVENT_KEY}${DATA_API_KEY}`
   }
@@ -98,6 +100,8 @@ const Carousel = (($) => {
       this._isPaused          = false
       this._isSliding         = false
 
+      this.touchTimeout       = null
+
       this._config            = this._getConfig(config)
       this._element           = $(element)[0]
       this._indicatorsElement = $(this._element).find(Selector.INDICATORS)[0]
@@ -120,10 +124,9 @@ const Carousel = (($) => {
     // public
 
     next() {
-      if (this._isSliding) {
-        throw new Error('Carousel is sliding')
+      if (!this._isSliding) {
+        this._slide(Direction.NEXT)
       }
-      this._slide(Direction.NEXT)
     }
 
     nextWhenVisible() {
@@ -134,10 +137,9 @@ const Carousel = (($) => {
     }
 
     prev() {
-      if (this._isSliding) {
-        throw new Error('Carousel is sliding')
+      if (!this._isSliding) {
+        this._slide(Direction.PREV)
       }
-      this._slide(Direction.PREVIOUS)
     }
 
     pause(event) {
@@ -195,7 +197,7 @@ const Carousel = (($) => {
 
       const direction = index > activeIndex ?
         Direction.NEXT :
-        Direction.PREVIOUS
+        Direction.PREV
 
       this._slide(direction, this._items[index])
     }
@@ -229,11 +231,26 @@ const Carousel = (($) => {
           .on(Event.KEYDOWN, (event) => this._keydown(event))
       }
 
-      if (this._config.pause === 'hover' &&
-        !('ontouchstart' in document.documentElement)) {
+      if (this._config.pause === 'hover') {
         $(this._element)
           .on(Event.MOUSEENTER, (event) => this.pause(event))
           .on(Event.MOUSELEAVE, (event) => this.cycle(event))
+        if ('ontouchstart' in document.documentElement) {
+          // if it's a touch-enabled device, mouseenter/leave are fired as
+          // part of the mouse compatibility events on first tap - the carousel
+          // would stop cycling until user tapped out of it;
+          // here, we listen for touchend, explicitly pause the carousel
+          // (as if it's the second time we tap on it, mouseenter compat event
+          // is NOT fired) and after a timeout (to allow for mouse compatibility
+          // events to fire) we explicitly restart cycling
+          $(this._element).on(Event.TOUCHEND, () => {
+            this.pause()
+            if (this.touchTimeout) {
+              clearTimeout(this.touchTimeout)
+            }
+            this.touchTimeout = setTimeout((event) => this.cycle(event), TOUCHEVENT_COMPAT_WAIT + this._config.interval)
+          })
+        }
       }
     }
 
@@ -263,7 +280,7 @@ const Carousel = (($) => {
 
     _getItemByDirection(direction, activeElement) {
       const isNextDirection = direction === Direction.NEXT
-      const isPrevDirection = direction === Direction.PREVIOUS
+      const isPrevDirection = direction === Direction.PREV
       const activeIndex     = this._getItemIndex(activeElement)
       const lastItemIndex   = this._items.length - 1
       const isGoingToWrap   = isPrevDirection && activeIndex === 0 ||
@@ -273,7 +290,7 @@ const Carousel = (($) => {
         return activeElement
       }
 
-      const delta     = direction === Direction.PREVIOUS ? -1 : 1
+      const delta     = direction === Direction.PREV ? -1 : 1
       const itemIndex = (activeIndex + delta) % this._items.length
 
       return itemIndex === -1 ?
@@ -282,9 +299,13 @@ const Carousel = (($) => {
 
 
     _triggerSlideEvent(relatedTarget, eventDirectionName) {
+      const targetIndex = this._getItemIndex(relatedTarget)
+      const fromIndex = this._getItemIndex($(this._element).find(Selector.ACTIVE_ITEM)[0])
       const slideEvent = $.Event(Event.SLIDE, {
         relatedTarget,
-        direction: eventDirectionName
+        direction: eventDirectionName,
+        from: fromIndex,
+        to: targetIndex
       })
 
       $(this._element).trigger(slideEvent)
@@ -310,9 +331,10 @@ const Carousel = (($) => {
 
     _slide(direction, element) {
       const activeElement = $(this._element).find(Selector.ACTIVE_ITEM)[0]
+      const activeElementIndex = this._getItemIndex(activeElement)
       const nextElement   = element || activeElement &&
         this._getItemByDirection(direction, activeElement)
-
+      const nextElementIndex = this._getItemIndex(nextElement)
       const isCycling = Boolean(this._interval)
 
       let directionalClassName
@@ -354,7 +376,9 @@ const Carousel = (($) => {
 
       const slidEvent = $.Event(Event.SLID, {
         relatedTarget: nextElement,
-        direction: eventDirectionName
+        direction: eventDirectionName,
+        from: activeElementIndex,
+        to: nextElementIndex
       })
 
       if (Util.supportsTransitionEnd() &&
diff --git a/js/src/collapse.js b/js/src/collapse.js
index ad8815993..bf1c738f5 100644
--- a/js/src/collapse.js
+++ b/js/src/collapse.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): collapse.js
+ * Bootstrap (v4.0.0-alpha.6): 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.5'
+  const VERSION             = '4.0.0-alpha.6'
   const DATA_KEY            = 'bs.collapse'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
@@ -56,7 +56,7 @@ const Collapse = (($) => {
   }
 
   const Selector = {
-    ACTIVES     : '.card > .show, .card > .collapsing',
+    ACTIVES     : '.show, .collapsing',
     DATA_TOGGLE : '[data-toggle="collapse"]'
   }
 
@@ -112,11 +112,8 @@ const Collapse = (($) => {
     }
 
     show() {
-      if (this._isTransitioning) {
-        throw new Error('Collapse is transitioning')
-      }
-
-      if ($(this._element).hasClass(ClassName.SHOW)) {
+      if (this._isTransitioning ||
+        $(this._element).hasClass(ClassName.SHOW)) {
         return
       }
 
@@ -124,7 +121,7 @@ const Collapse = (($) => {
       let activesData
 
       if (this._parent) {
-        actives = $.makeArray($(this._parent).find(Selector.ACTIVES))
+        actives = $.makeArray($(this._parent).children().children(Selector.ACTIVES))
         if (!actives.length) {
           actives = null
         }
@@ -157,7 +154,6 @@ const Collapse = (($) => {
         .addClass(ClassName.COLLAPSING)
 
       this._element.style[dimension] = 0
-      this._element.setAttribute('aria-expanded', true)
 
       if (this._triggerArray.length) {
         $(this._triggerArray)
@@ -196,11 +192,8 @@ const Collapse = (($) => {
     }
 
     hide() {
-      if (this._isTransitioning) {
-        throw new Error('Collapse is transitioning')
-      }
-
-      if (!$(this._element).hasClass(ClassName.SHOW)) {
+      if (this._isTransitioning ||
+        !$(this._element).hasClass(ClassName.SHOW)) {
         return
       }
 
@@ -211,10 +204,8 @@ const Collapse = (($) => {
       }
 
       const dimension       = this._getDimension()
-      const offsetDimension = dimension === Dimension.WIDTH ?
-        'offsetWidth' : 'offsetHeight'
 
-      this._element.style[dimension] = `${this._element[offsetDimension]}px`
+      this._element.style[dimension] = `${this._element.getBoundingClientRect()[dimension]}px`
 
       Util.reflow(this._element)
 
@@ -223,8 +214,6 @@ const Collapse = (($) => {
         .removeClass(ClassName.COLLAPSE)
         .removeClass(ClassName.SHOW)
 
-      this._element.setAttribute('aria-expanded', false)
-
       if (this._triggerArray.length) {
         $(this._triggerArray)
           .addClass(ClassName.COLLAPSED)
@@ -300,7 +289,6 @@ const Collapse = (($) => {
     _addAriaAndCollapsedClass(element, triggerArray) {
       if (element) {
         const isOpen = $(element).hasClass(ClassName.SHOW)
-        element.setAttribute('aria-expanded', isOpen)
 
         if (triggerArray.length) {
           $(triggerArray)
@@ -357,7 +345,9 @@ const Collapse = (($) => {
    */
 
   $(document).on(Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
-    event.preventDefault()
+    if (!/input|textarea/i.test(event.target.tagName)) {
+      event.preventDefault()
+    }
 
     const target = Collapse._getTargetFromElement(this)
     const data   = $(target).data(DATA_KEY)
diff --git a/js/src/dropdown.js b/js/src/dropdown.js
index 97bba1c76..acc3ed453 100644
--- a/js/src/dropdown.js
+++ b/js/src/dropdown.js
@@ -1,15 +1,24 @@
+/* global Popper */
+
 import Util from './util'
 
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): dropdown.js
+ * Bootstrap (v4.0.0-alpha.6): dropdown.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
 
 const Dropdown = (($) => {
 
+  /**
+   * Check for Popper dependency
+   * Popper - https://popper.js.org
+   */
+  if (typeof Popper === 'undefined') {
+    throw new Error('Bootstrap dropdown require Popper.js (https://popper.js.org)')
+  }
 
   /**
    * ------------------------------------------------------------------------
@@ -18,15 +27,18 @@ const Dropdown = (($) => {
    */
 
   const NAME                     = 'dropdown'
-  const VERSION                  = '4.0.0-alpha.5'
+  const VERSION                  = '4.0.0-alpha.6'
   const DATA_KEY                 = 'bs.dropdown'
   const EVENT_KEY                = `.${DATA_KEY}`
   const DATA_API_KEY             = '.data-api'
   const JQUERY_NO_CONFLICT       = $.fn[NAME]
   const ESCAPE_KEYCODE           = 27 // KeyboardEvent.which value for Escape (Esc) key
+  const SPACE_KEYCODE            = 32 // KeyboardEvent.which value for space key
+  const TAB_KEYCODE              = 9 // KeyboardEvent.which value for tab key
   const ARROW_UP_KEYCODE         = 38 // KeyboardEvent.which value for up arrow key
   const ARROW_DOWN_KEYCODE       = 40 // KeyboardEvent.which value for down arrow key
   const RIGHT_MOUSE_BUTTON_WHICH = 3 // MouseEvent.which value for the right button (assuming a right-handed mouse)
+  const REGEXP_KEYDOWN           = new RegExp(`${ARROW_UP_KEYCODE}|${ARROW_DOWN_KEYCODE}|${ESCAPE_KEYCODE}`)
 
   const Event = {
     HIDE             : `hide${EVENT_KEY}`,
@@ -35,24 +47,43 @@ const Dropdown = (($) => {
     SHOWN            : `shown${EVENT_KEY}`,
     CLICK            : `click${EVENT_KEY}`,
     CLICK_DATA_API   : `click${EVENT_KEY}${DATA_API_KEY}`,
-    KEYDOWN_DATA_API : `keydown${EVENT_KEY}${DATA_API_KEY}`
+    KEYDOWN_DATA_API : `keydown${EVENT_KEY}${DATA_API_KEY}`,
+    KEYUP_DATA_API   : `keyup${EVENT_KEY}${DATA_API_KEY}`
   }
 
   const ClassName = {
-    BACKDROP : 'dropdown-backdrop',
-    DISABLED : 'disabled',
-    SHOW     : 'show'
+    DISABLED  : 'disabled',
+    SHOW      : 'show',
+    DROPUP    : 'dropup',
+    MENURIGHT : 'dropdown-menu-right',
+    MENULEFT  : 'dropdown-menu-left'
   }
 
   const Selector = {
-    BACKDROP      : '.dropdown-backdrop',
     DATA_TOGGLE   : '[data-toggle="dropdown"]',
     FORM_CHILD    : '.dropdown form',
-    ROLE_MENU     : '[role="menu"]',
-    ROLE_LISTBOX  : '[role="listbox"]',
+    MENU          : '.dropdown-menu',
     NAVBAR_NAV    : '.navbar-nav',
-    VISIBLE_ITEMS : '[role="menu"] li:not(.disabled) a, '
-                  + '[role="listbox"] li:not(.disabled) a'
+    VISIBLE_ITEMS : '.dropdown-menu .dropdown-item:not(.disabled)'
+  }
+
+  const AttachmentMap = {
+    TOP       : 'top-start',
+    TOPEND    : 'top-end',
+    BOTTOM    : 'bottom-start',
+    BOTTOMEND : 'bottom-end'
+  }
+
+  const Default = {
+    placement   : AttachmentMap.BOTTOM,
+    offset      : 0,
+    flip        : true
+  }
+
+  const DefaultType = {
+    placement   : 'string',
+    offset      : '(number|string)',
+    flip        : 'boolean'
   }
 
 
@@ -64,8 +95,11 @@ const Dropdown = (($) => {
 
   class Dropdown {
 
-    constructor(element) {
+    constructor(element, config) {
       this._element = element
+      this._popper  = null
+      this._config = this._getConfig(config)
+      this._menu = this._getMenuElement()
 
       this._addEventListeners()
     }
@@ -77,75 +111,163 @@ const Dropdown = (($) => {
       return VERSION
     }
 
+    static get Default() {
+      return Default
+    }
+
+    static get DefaultType() {
+      return DefaultType
+    }
 
     // public
 
     toggle() {
-      if (this.disabled || $(this).hasClass(ClassName.DISABLED)) {
-        return false
+      if (this._element.disabled || $(this._element).hasClass(ClassName.DISABLED)) {
+        return
       }
 
-      const parent   = Dropdown._getParentFromElement(this)
-      const isActive = $(parent).hasClass(ClassName.SHOW)
+      const parent   = Dropdown._getParentFromElement(this._element)
+      const isActive = $(this._menu).hasClass(ClassName.SHOW)
 
       Dropdown._clearMenus()
 
       if (isActive) {
-        return false
-      }
-
-      if ('ontouchstart' in document.documentElement &&
-         !$(parent).closest(Selector.NAVBAR_NAV).length) {
-
-        // if mobile we use a backdrop because click events don't delegate
-        const dropdown     = document.createElement('div')
-        dropdown.className = ClassName.BACKDROP
-        $(dropdown).insertBefore(this)
-        $(dropdown).on('click', Dropdown._clearMenus)
+        return
       }
 
       const relatedTarget = {
-        relatedTarget : this
+        relatedTarget : this._element
       }
-      const showEvent     = $.Event(Event.SHOW, relatedTarget)
+      const showEvent = $.Event(Event.SHOW, relatedTarget)
 
       $(parent).trigger(showEvent)
 
       if (showEvent.isDefaultPrevented()) {
-        return false
+        return
       }
 
-      this.focus()
-      this.setAttribute('aria-expanded', true)
+      let element = this._element
+      // for dropup with alignment we use the parent as popper container
+      if ($(parent).hasClass(ClassName.DROPUP)) {
+        if ($(this._menu).hasClass(ClassName.MENULEFT) || $(this._menu).hasClass(ClassName.MENURIGHT)) {
+          element = parent
+        }
+      }
+      this._popper = new Popper(element, this._menu, {
+        placement : this._getPlacement(),
+        modifiers : {
+          offset : {
+            offset : this._config.offset
+          },
+          flip : {
+            enabled : this._config.flip
+          }
+        }
+      })
 
-      $(parent).toggleClass(ClassName.SHOW)
-      $(parent).trigger($.Event(Event.SHOWN, relatedTarget))
+      // if this is a touch-enabled device we add extra
+      // empty mouseover listeners to the body's immediate children;
+      // only needed because of broken event delegation on iOS
+      // https://www.quirksmode.org/blog/archives/2014/02/mouse_event_bub.html
+      if ('ontouchstart' in document.documentElement &&
+         !$(parent).closest(Selector.NAVBAR_NAV).length) {
+        $('body').children().on('mouseover', null, $.noop)
+      }
 
-      return false
+      this._element.focus()
+      this._element.setAttribute('aria-expanded', true)
+
+      $(this._menu).toggleClass(ClassName.SHOW)
+      $(parent)
+        .toggleClass(ClassName.SHOW)
+        .trigger($.Event(Event.SHOWN, relatedTarget))
     }
 
     dispose() {
       $.removeData(this._element, DATA_KEY)
       $(this._element).off(EVENT_KEY)
       this._element = null
+      this._menu = null
+      if (this._popper !== null) {
+        this._popper.destroy()
+      }
+      this._popper = null
     }
 
+    update() {
+      if (this._popper !== null) {
+        this._popper.scheduleUpdate()
+      }
+    }
 
     // private
 
     _addEventListeners() {
-      $(this._element).on(Event.CLICK, this.toggle)
+      $(this._element).on(Event.CLICK, (event) => {
+        event.preventDefault()
+        event.stopPropagation()
+        this.toggle()
+      })
+    }
+
+    _getConfig(config) {
+      const elementData = $(this._element).data()
+      if (elementData.placement !== undefined) {
+        elementData.placement = AttachmentMap[elementData.placement.toUpperCase()]
+      }
+
+      config = $.extend(
+        {},
+        this.constructor.Default,
+        $(this._element).data(),
+        config
+      )
+
+      Util.typeCheckConfig(
+        NAME,
+        config,
+        this.constructor.DefaultType
+      )
+
+      return config
+    }
+
+    _getMenuElement() {
+      if (!this._menu) {
+        const parent = Dropdown._getParentFromElement(this._element)
+        this._menu = $(parent).find(Selector.MENU)[0]
+      }
+      return this._menu
     }
 
+    _getPlacement() {
+      const $parentDropdown = $(this._element).parent()
+      let placement = this._config.placement
+
+      // Handle dropup
+      if ($parentDropdown.hasClass(ClassName.DROPUP) || this._config.placement === AttachmentMap.TOP) {
+        placement = AttachmentMap.TOP
+        if ($(this._menu).hasClass(ClassName.MENURIGHT)) {
+          placement = AttachmentMap.TOPEND
+        }
+      }
+      else {
+        if ($(this._menu).hasClass(ClassName.MENURIGHT)) {
+          placement = AttachmentMap.BOTTOMEND
+        }
+      }
+      return placement
+    }
 
     // static
 
     static _jQueryInterface(config) {
       return this.each(function () {
         let data = $(this).data(DATA_KEY)
+        const _config = typeof config === 'object' ? config : null
 
         if (!data) {
-          data = new Dropdown(this)
+          data = new Dropdown(this, _config)
           $(this).data(DATA_KEY, data)
         }
 
@@ -153,36 +275,37 @@ const Dropdown = (($) => {
           if (data[config] === undefined) {
             throw new Error(`No method named "${config}"`)
           }
-          data[config].call(this)
+          data[config]()
         }
       })
     }
 
     static _clearMenus(event) {
-      if (event && event.which === RIGHT_MOUSE_BUTTON_WHICH) {
+      if (event && (event.which === RIGHT_MOUSE_BUTTON_WHICH ||
+        event.type === 'keyup' && event.which !== TAB_KEYCODE)) {
         return
       }
 
-      const backdrop = $(Selector.BACKDROP)[0]
-      if (backdrop) {
-        backdrop.parentNode.removeChild(backdrop)
-      }
-
       const toggles = $.makeArray($(Selector.DATA_TOGGLE))
-
       for (let i = 0; i < toggles.length; i++) {
         const parent        = Dropdown._getParentFromElement(toggles[i])
+        const context       = $(toggles[i]).data(DATA_KEY)
         const relatedTarget = {
           relatedTarget : toggles[i]
         }
 
+        if (!context) {
+          continue
+        }
+
+        const dropdownMenu = context._menu
         if (!$(parent).hasClass(ClassName.SHOW)) {
           continue
         }
 
-        if (event && event.type === 'click' &&
-           /input|textarea/i.test(event.target.tagName) &&
-           $.contains(parent, event.target)) {
+        if (event && (event.type === 'click' &&
+            /input|textarea/i.test(event.target.tagName) || event.type === 'keyup' && event.which === TAB_KEYCODE)
+            && $.contains(parent, event.target)) {
           continue
         }
 
@@ -192,8 +315,15 @@ const Dropdown = (($) => {
           continue
         }
 
+        // if this is a touch-enabled device we remove the extra
+        // empty mouseover listeners we added for iOS support
+        if ('ontouchstart' in document.documentElement) {
+          $('body').children().off('mouseover', null, $.noop)
+        }
+
         toggles[i].setAttribute('aria-expanded', 'false')
 
+        $(dropdownMenu).removeClass(ClassName.SHOW)
         $(parent)
           .removeClass(ClassName.SHOW)
           .trigger($.Event(Event.HIDDEN, relatedTarget))
@@ -212,7 +342,7 @@ const Dropdown = (($) => {
     }
 
     static _dataApiKeydownHandler(event) {
-      if (!/(38|40|27|32)/.test(event.which) ||
+      if (!REGEXP_KEYDOWN.test(event.which) || /button/i.test(event.target.tagName) && event.which === SPACE_KEYCODE ||
          /input|textarea/i.test(event.target.tagName)) {
         return
       }
@@ -227,8 +357,8 @@ const Dropdown = (($) => {
       const parent   = Dropdown._getParentFromElement(this)
       const isActive = $(parent).hasClass(ClassName.SHOW)
 
-      if (!isActive && event.which !== ESCAPE_KEYCODE ||
-           isActive && event.which === ESCAPE_KEYCODE) {
+      if (!isActive && (event.which !== ESCAPE_KEYCODE || event.which !== SPACE_KEYCODE) ||
+           isActive && (event.which === ESCAPE_KEYCODE || event.which === SPACE_KEYCODE)) {
 
         if (event.which === ESCAPE_KEYCODE) {
           const toggle = $(parent).find(Selector.DATA_TOGGLE)[0]
@@ -273,10 +403,13 @@ const Dropdown = (($) => {
 
   $(document)
     .on(Event.KEYDOWN_DATA_API, Selector.DATA_TOGGLE,  Dropdown._dataApiKeydownHandler)
-    .on(Event.KEYDOWN_DATA_API, Selector.ROLE_MENU,    Dropdown._dataApiKeydownHandler)
-    .on(Event.KEYDOWN_DATA_API, Selector.ROLE_LISTBOX, Dropdown._dataApiKeydownHandler)
-    .on(Event.CLICK_DATA_API, Dropdown._clearMenus)
-    .on(Event.CLICK_DATA_API, Selector.DATA_TOGGLE, Dropdown.prototype.toggle)
+    .on(Event.KEYDOWN_DATA_API, Selector.MENU, Dropdown._dataApiKeydownHandler)
+    .on(`${Event.CLICK_DATA_API} ${Event.KEYUP_DATA_API}`, Dropdown._clearMenus)
+    .on(Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
+      event.preventDefault()
+      event.stopPropagation()
+      Dropdown._jQueryInterface.call($(this), 'toggle')
+    })
     .on(Event.CLICK_DATA_API, Selector.FORM_CHILD, (e) => {
       e.stopPropagation()
     })
diff --git a/js/src/modal.js b/js/src/modal.js
index 94abd19f4..02d463945 100644
--- a/js/src/modal.js
+++ b/js/src/modal.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): modal.js
+ * Bootstrap (v4.0.0-alpha.6): modal.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,7 +18,7 @@ const Modal = (($) => {
    */
 
   const NAME                         = 'modal'
-  const VERSION                      = '4.0.0-alpha.5'
+  const VERSION                      = '4.0.0-alpha.6'
   const DATA_KEY                     = 'bs.modal'
   const EVENT_KEY                    = `.${DATA_KEY}`
   const DATA_API_KEY                 = '.data-api'
@@ -67,7 +67,8 @@ const Modal = (($) => {
     DIALOG             : '.modal-dialog',
     DATA_TOGGLE        : '[data-toggle="modal"]',
     DATA_DISMISS       : '[data-dismiss="modal"]',
-    FIXED_CONTENT      : '.navbar-fixed-top, .navbar-fixed-bottom, .is-fixed'
+    FIXED_CONTENT      : '.fixed-top, .fixed-bottom, .is-fixed, .sticky-top',
+    NAVBAR_TOGGLER     : '.navbar-toggler'
   }
 
 
@@ -87,7 +88,6 @@ const Modal = (($) => {
       this._isShown             = false
       this._isBodyOverflowing   = false
       this._ignoreBackdropClick = false
-      this._isTransitioning     = false
       this._originalBodyPadding = 0
       this._scrollbarWidth      = 0
     }
@@ -112,13 +112,13 @@ const Modal = (($) => {
 
     show(relatedTarget) {
       if (this._isTransitioning) {
-        throw new Error('Modal is transitioning')
+        return
       }
 
-      if (Util.supportsTransitionEnd() &&
-        $(this._element).hasClass(ClassName.FADE)) {
+      if (Util.supportsTransitionEnd() && $(this._element).hasClass(ClassName.FADE)) {
         this._isTransitioning = true
       }
+
       const showEvent = $.Event(Event.SHOW, {
         relatedTarget
       })
@@ -161,17 +161,18 @@ const Modal = (($) => {
         event.preventDefault()
       }
 
-      if (this._isTransitioning) {
-        throw new Error('Modal is transitioning')
+      if (this._isTransitioning || !this._isShown) {
+        return
       }
 
-      const transition = Util.supportsTransitionEnd() &&
-        $(this._element).hasClass(ClassName.FADE)
+      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()) {
@@ -191,6 +192,7 @@ const Modal = (($) => {
       $(this._dialog).off(Event.MOUSEDOWN_DISMISS)
 
       if (transition) {
+
         $(this._element)
           .one(Util.TRANSITION_END, (event) => this._hideModal(event))
           .emulateTransitionEnd(TRANSITION_DURATION)
@@ -211,10 +213,12 @@ const Modal = (($) => {
       this._isShown             = null
       this._isBodyOverflowing   = null
       this._ignoreBackdropClick = null
-      this._originalBodyPadding = null
       this._scrollbarWidth      = null
     }
 
+    handleUpdate() {
+      this._adjustDialog()
+    }
 
     // private
 
@@ -285,6 +289,7 @@ const Modal = (($) => {
       if (this._isShown && this._config.keyboard) {
         $(this._element).on(Event.KEYDOWN_DISMISS, (event) => {
           if (event.which === ESCAPE_KEYCODE) {
+            event.preventDefault()
             this.hide()
           }
         })
@@ -296,7 +301,7 @@ const Modal = (($) => {
 
     _setResizeEvent() {
       if (this._isShown) {
-        $(window).on(Event.RESIZE, (event) => this._handleUpdate(event))
+        $(window).on(Event.RESIZE, (event) => this.handleUpdate(event))
       } else {
         $(window).off(Event.RESIZE)
       }
@@ -304,7 +309,7 @@ const Modal = (($) => {
 
     _hideModal() {
       this._element.style.display = 'none'
-      this._element.setAttribute('aria-hidden', 'true')
+      this._element.setAttribute('aria-hidden', true)
       this._isTransitioning = false
       this._showBackdrop(() => {
         $(document.body).removeClass(ClassName.OPEN)
@@ -401,10 +406,6 @@ const Modal = (($) => {
     // todo (fat): these should probably be refactored out of modal.js
     // ----------------------------------------------------------------------
 
-    _handleUpdate() {
-      this._adjustDialog()
-    }
-
     _adjustDialog() {
       const isModalOverflowing =
         this._element.scrollHeight > document.documentElement.clientHeight
@@ -429,28 +430,60 @@ const Modal = (($) => {
     }
 
     _setScrollbar() {
-      const bodyPadding = parseInt(
-        $(Selector.FIXED_CONTENT).css('padding-right') || 0,
-        10
-      )
+      if (this._isBodyOverflowing) {
+        // Note: DOMNode.style.paddingRight returns the actual value or '' if not set
+        //   while $(DOMNode).css('padding-right') returns the calculated value or 0 if not set
+
+        // Adjust fixed content padding
+        $(Selector.FIXED_CONTENT).each((index, element) => {
+          const actualPadding = $(element)[0].style.paddingRight
+          const calculatedPadding = $(element).css('padding-right')
+          $(element).data('padding-right', actualPadding).css('padding-right', `${parseFloat(calculatedPadding) + this._scrollbarWidth}px`)
+        })
 
-      this._originalBodyPadding = document.body.style.paddingRight || ''
+        // Adjust navbar-toggler margin
+        $(Selector.NAVBAR_TOGGLER).each((index, element) => {
+          const actualMargin = $(element)[0].style.marginRight
+          const calculatedMargin = $(element).css('margin-right')
+          $(element).data('margin-right', actualMargin).css('margin-right', `${parseFloat(calculatedMargin) + this._scrollbarWidth}px`)
+        })
 
-      if (this._isBodyOverflowing) {
-        document.body.style.paddingRight =
-          `${bodyPadding + this._scrollbarWidth}px`
+        // Adjust body padding
+        const actualPadding = document.body.style.paddingRight
+        const calculatedPadding = $('body').css('padding-right')
+        $('body').data('padding-right', actualPadding).css('padding-right', `${parseFloat(calculatedPadding) + this._scrollbarWidth}px`)
       }
     }
 
     _resetScrollbar() {
-      document.body.style.paddingRight = this._originalBodyPadding
+      // Restore fixed content padding
+      $(Selector.FIXED_CONTENT).each((index, element) => {
+        const padding = $(element).data('padding-right')
+        if (typeof padding !== 'undefined') {
+          $(element).css('padding-right', padding).removeData('padding-right')
+        }
+      })
+
+      // Restore navbar-toggler margin
+      $(Selector.NAVBAR_TOGGLER).each((index, element) => {
+        const margin = $(element).data('margin-right')
+        if (typeof margin !== 'undefined') {
+          $(element).css('margin-right', margin).removeData('margin-right')
+        }
+      })
+
+      // Restore body padding
+      const padding = $('body').data('padding-right')
+      if (typeof padding !== 'undefined') {
+        $('body').css('padding-right', padding).removeData('padding-right')
+      }
     }
 
     _getScrollbarWidth() { // thx d.walsh
       const scrollDiv = document.createElement('div')
       scrollDiv.className = ClassName.SCROLLBAR_MEASURER
       document.body.appendChild(scrollDiv)
-      const scrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth
+      const scrollbarWidth = scrollDiv.getBoundingClientRect().width - scrollDiv.clientWidth
       document.body.removeChild(scrollDiv)
       return scrollbarWidth
     }
diff --git a/js/src/popover.js b/js/src/popover.js
index 33bc9e48c..a068420d6 100644
--- a/js/src/popover.js
+++ b/js/src/popover.js
@@ -3,7 +3,7 @@ import Tooltip from './tooltip'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): popover.js
+ * Bootstrap (v4.0.0-alpha.6): popover.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -18,16 +18,19 @@ const Popover = (($) => {
    */
 
   const NAME                = 'popover'
-  const VERSION             = '4.0.0-alpha.5'
+  const VERSION             = '4.0.0-alpha.6'
   const DATA_KEY            = 'bs.popover'
   const EVENT_KEY           = `.${DATA_KEY}`
   const JQUERY_NO_CONFLICT  = $.fn[NAME]
+  const CLASS_PREFIX        = 'bs-popover'
+  const BSCLS_PREFIX_REGEX  = new RegExp(`(^|\\s)${CLASS_PREFIX}\\S+`, 'g')
 
   const Default = $.extend({}, Tooltip.Default, {
     placement : 'right',
     trigger   : 'click',
     content   : '',
     template  : '<div class="popover" role="tooltip">'
+              + '<div class="arrow" x-arrow></div>'
               + '<h3 class="popover-title"></h3>'
               + '<div class="popover-content"></div></div>'
   })
@@ -106,6 +109,10 @@ const Popover = (($) => {
       return this.getTitle() || this._getContent()
     }
 
+    addAttachmentClass(attachment) {
+      $(this.getTipElement()).addClass(`${CLASS_PREFIX}-${attachment}`)
+    }
+
     getTipElement() {
       return this.tip = this.tip || $(this.config.template)[0]
     }
@@ -118,8 +125,6 @@ const Popover = (($) => {
       this.setElementContent($tip.find(Selector.CONTENT), this._getContent())
 
       $tip.removeClass(`${ClassName.FADE} ${ClassName.SHOW}`)
-
-      this.cleanupTether()
     }
 
     // private
@@ -131,6 +136,14 @@ const Popover = (($) => {
               this.config.content)
     }
 
+    _cleanTipClass() {
+      const $tip = $(this.getTipElement())
+      const tabClass = $tip.attr('class').match(BSCLS_PREFIX_REGEX)
+      if (tabClass !== null && tabClass.length > 0) {
+        $tip.removeClass(tabClass.join(''))
+      }
+    }
+
 
     // static
 
diff --git a/js/src/scrollspy.js b/js/src/scrollspy.js
index 0a4708bf9..7ea9f2483 100644
--- a/js/src/scrollspy.js
+++ b/js/src/scrollspy.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): scrollspy.js
+ * Bootstrap (v4.0.0-alpha.6): 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.5'
+  const VERSION            = '4.0.0-alpha.6'
   const DATA_KEY           = 'bs.scrollspy'
   const EVENT_KEY          = `.${DATA_KEY}`
   const DATA_API_KEY       = '.data-api'
@@ -45,18 +45,15 @@ const ScrollSpy = (($) => {
   const ClassName = {
     DROPDOWN_ITEM : 'dropdown-item',
     DROPDOWN_MENU : 'dropdown-menu',
-    NAV_LINK      : 'nav-link',
-    NAV           : 'nav',
     ACTIVE        : 'active'
   }
 
   const Selector = {
     DATA_SPY        : '[data-spy="scroll"]',
     ACTIVE          : '.active',
-    LIST_ITEM       : '.list-item',
-    LI              : 'li',
-    LI_DROPDOWN     : 'li.dropdown',
+    NAV_LIST_GROUP  : '.nav, .list-group',
     NAV_LINKS       : '.nav-link',
+    LIST_ITEMS      : '.list-group-item',
     DROPDOWN        : '.dropdown',
     DROPDOWN_ITEMS  : '.dropdown-item',
     DROPDOWN_TOGGLE : '.dropdown-toggle'
@@ -81,6 +78,7 @@ const ScrollSpy = (($) => {
       this._scrollElement = element.tagName === 'BODY' ? window : element
       this._config        = this._getConfig(config)
       this._selector      = `${this._config.target} ${Selector.NAV_LINKS},`
+                          + `${this._config.target} ${Selector.LIST_ITEMS},`
                           + `${this._config.target} ${Selector.DROPDOWN_ITEMS}`
       this._offsets       = []
       this._targets       = []
@@ -133,12 +131,15 @@ const ScrollSpy = (($) => {
             target = $(targetSelector)[0]
           }
 
-          if (target && (target.offsetWidth || target.offsetHeight)) {
-            // todo (fat): remove sketch reliance on jQuery position/offset
-            return [
-              $(target)[offsetMethod]().top + offsetBase,
-              targetSelector
-            ]
+          if (target) {
+            const targetBCR = target.getBoundingClientRect()
+            if (targetBCR.width || targetBCR.height) {
+              // todo (fat): remove sketch reliance on jQuery position/offset
+              return [
+                $(target)[offsetMethod]().top + offsetBase,
+                targetSelector
+              ]
+            }
           }
           return null
         })
@@ -186,7 +187,7 @@ const ScrollSpy = (($) => {
 
     _getScrollTop() {
       return this._scrollElement === window ?
-          this._scrollElement.scrollY : this._scrollElement.scrollTop
+          this._scrollElement.pageYOffset : this._scrollElement.scrollTop
     }
 
     _getScrollHeight() {
@@ -198,7 +199,7 @@ const ScrollSpy = (($) => {
 
     _getOffsetHeight() {
       return this._scrollElement === window ?
-          window.innerHeight : this._scrollElement.offsetHeight
+          window.innerHeight : this._scrollElement.getBoundingClientRect().height
     }
 
     _process() {
@@ -256,9 +257,11 @@ const ScrollSpy = (($) => {
         $link.closest(Selector.DROPDOWN).find(Selector.DROPDOWN_TOGGLE).addClass(ClassName.ACTIVE)
         $link.addClass(ClassName.ACTIVE)
       } 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)
+        // Set triggered link as active
+        $link.addClass(ClassName.ACTIVE)
+        // Set triggered links parents as active
+        // With both <ul> and <nav> markup a parent is the previous sibling of any nav ancestor
+        $link.parents(Selector.NAV_LIST_GROUP).prev(`${Selector.NAV_LINKS}, ${Selector.LIST_ITEMS}`).addClass(ClassName.ACTIVE)
       }
 
       $(this._scrollElement).trigger(Event.ACTIVATE, {
diff --git a/js/src/tab.js b/js/src/tab.js
index 2f4e453e0..c7bc520df 100644
--- a/js/src/tab.js
+++ b/js/src/tab.js
@@ -3,7 +3,7 @@ import Util from './util'
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): tab.js
+ * Bootstrap (v4.0.0-alpha.6): 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.5'
+  const VERSION             = '4.0.0-alpha.6'
   const DATA_KEY            = 'bs.tab'
   const EVENT_KEY           = `.${DATA_KEY}`
   const DATA_API_KEY        = '.data-api'
@@ -42,14 +42,10 @@ const Tab = (($) => {
   }
 
   const Selector = {
-    A                     : 'a',
-    LI                    : 'li',
     DROPDOWN              : '.dropdown',
-    LIST                  : 'ul:not(.dropdown-menu), ol:not(.dropdown-menu)',
-    FADE_CHILD            : '> .nav-item .fade, > .fade',
+    NAV_LIST_GROUP        : '.nav, .list-group',
     ACTIVE                : '.active',
-    ACTIVE_CHILD          : '> .nav-item > .active, > .active',
-    DATA_TOGGLE           : '[data-toggle="tab"], [data-toggle="pill"]',
+    DATA_TOGGLE           : '[data-toggle="tab"], [data-toggle="pill"], [data-toggle="list"]',
     DROPDOWN_TOGGLE       : '.dropdown-toggle',
     DROPDOWN_ACTIVE_CHILD : '> .dropdown-menu .active'
   }
@@ -87,7 +83,7 @@ const Tab = (($) => {
 
       let target
       let previous
-      const listElement = $(this._element).closest(Selector.LIST)[0]
+      const listElement = $(this._element).closest(Selector.NAV_LIST_GROUP)[0]
       const selector    = Util.getSelectorFromElement(this._element)
 
       if (listElement) {
@@ -144,7 +140,7 @@ const Tab = (($) => {
     }
 
     dispose() {
-      $.removeClass(this._element, DATA_KEY)
+      $.removeData(this._element, DATA_KEY)
       this._element = null
     }
 
@@ -152,11 +148,10 @@ const Tab = (($) => {
     // private
 
     _activate(element, container, callback) {
-      const active          = $(container).find(Selector.ACTIVE_CHILD)[0]
+      const active          = $(container).find(Selector.ACTIVE)[0]
       const isTransitioning = callback
         && Util.supportsTransitionEnd()
-        && (active && $(active).hasClass(ClassName.FADE)
-           || Boolean($(container).find(Selector.FADE_CHILD)[0]))
+        && (active && $(active).hasClass(ClassName.FADE))
 
       const complete = () => this._transitionComplete(
         element,
diff --git a/js/src/tooltip.js b/js/src/tooltip.js
index 0c1d381b9..1d53b0470 100644
--- a/js/src/tooltip.js
+++ b/js/src/tooltip.js
@@ -1,11 +1,11 @@
-/* global Tether */
+/* global Popper */
 
 import Util from './util'
 
 
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): tooltip.js
+ * Bootstrap (v4.0.0-alpha.6): tooltip.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -13,11 +13,11 @@ import Util from './util'
 const Tooltip = (($) => {
 
   /**
-   * Check for Tether dependency
-   * Tether - http://tether.io/
+   * Check for Popper dependency
+   * Popper - https://popper.js.org
    */
-  if (typeof Tether === 'undefined') {
-    throw new Error('Bootstrap tooltips require Tether (http://tether.io/)')
+  if (typeof Popper === 'undefined') {
+    throw new Error('Bootstrap tooltips require Popper.js (https://popper.js.org)')
   }
 
 
@@ -28,47 +28,50 @@ const Tooltip = (($) => {
    */
 
   const NAME                = 'tooltip'
-  const VERSION             = '4.0.0-alpha.5'
+  const VERSION             = '4.0.0-alpha.6'
   const DATA_KEY            = 'bs.tooltip'
   const EVENT_KEY           = `.${DATA_KEY}`
   const JQUERY_NO_CONFLICT  = $.fn[NAME]
   const TRANSITION_DURATION = 150
-  const CLASS_PREFIX        = 'bs-tether'
-
-  const Default = {
-    animation   : true,
-    template    : '<div class="tooltip" role="tooltip">'
-                + '<div class="tooltip-inner"></div></div>',
-    trigger     : 'hover focus',
-    title       : '',
-    delay       : 0,
-    html        : false,
-    selector    : false,
-    placement   : 'top',
-    offset      : '0 0',
-    constraints : [],
-    container   : false
-  }
+  const CLASS_PREFIX        = 'bs-tooltip'
+  const BSCLS_PREFIX_REGEX = new RegExp(`(^|\\s)${CLASS_PREFIX}\\S+`, 'g')
 
   const DefaultType = {
-    animation   : 'boolean',
-    template    : 'string',
-    title       : '(string|element|function)',
-    trigger     : 'string',
-    delay       : '(number|object)',
-    html        : 'boolean',
-    selector    : '(string|boolean)',
-    placement   : '(string|function)',
-    offset      : 'string',
-    constraints : 'array',
-    container   : '(string|element|boolean)'
+    animation           : 'boolean',
+    template            : 'string',
+    title               : '(string|element|function)',
+    trigger             : 'string',
+    delay               : '(number|object)',
+    html                : 'boolean',
+    selector            : '(string|boolean)',
+    placement           : '(string|function)',
+    offset              : '(number|string)',
+    container           : '(string|element|boolean)',
+    fallbackPlacement   : '(string|array)'
   }
 
   const AttachmentMap = {
-    TOP    : 'bottom center',
-    RIGHT  : 'middle left',
-    BOTTOM : 'top center',
-    LEFT   : 'middle right'
+    AUTO   : 'auto',
+    TOP    : 'top',
+    RIGHT  : 'right',
+    BOTTOM : 'bottom',
+    LEFT   : 'left'
+  }
+
+  const Default = {
+    animation           : true,
+    template            : '<div class="tooltip" role="tooltip">'
+                        + '<div class="arrow" x-arrow></div>'
+                        + '<div class="tooltip-inner"></div></div>',
+    trigger             : 'hover focus',
+    title               : '',
+    delay               : 0,
+    html                : false,
+    selector            : false,
+    placement           : 'top',
+    offset              : 0,
+    container           : false,
+    fallbackPlacement   : 'flip'
   }
 
   const HoverState = {
@@ -99,11 +102,6 @@ const Tooltip = (($) => {
     TOOLTIP_INNER : '.tooltip-inner'
   }
 
-  const TetherClass = {
-    element : false,
-    enabled : false
-  }
-
   const Trigger = {
     HOVER  : 'hover',
     FOCUS  : 'focus',
@@ -123,12 +121,11 @@ const Tooltip = (($) => {
     constructor(element, config) {
 
       // private
-      this._isEnabled        = true
-      this._timeout          = 0
-      this._hoverState       = ''
-      this._activeTrigger    = {}
-      this._isTransitioning  = false
-      this._tether           = null
+      this._isEnabled     = true
+      this._timeout       = 0
+      this._hoverState    = ''
+      this._activeTrigger = {}
+      this._popper        = null
 
       // protected
       this.element = element
@@ -220,8 +217,6 @@ const Tooltip = (($) => {
     dispose() {
       clearTimeout(this._timeout)
 
-      this.cleanupTether()
-
       $.removeData(this.element, this.constructor.DATA_KEY)
 
       $(this.element).off(this.constructor.EVENT_KEY)
@@ -235,7 +230,10 @@ const Tooltip = (($) => {
       this._timeout       = null
       this._hoverState    = null
       this._activeTrigger = null
-      this._tether        = null
+      if (this._popper !== null) {
+        this._popper.destroy()
+      }
+      this._popper        = null
 
       this.element = null
       this.config  = null
@@ -249,9 +247,6 @@ const Tooltip = (($) => {
 
       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)
 
         const isInTheDom = $.contains(
@@ -280,35 +275,54 @@ const Tooltip = (($) => {
           this.config.placement
 
         const attachment = this._getAttachment(placement)
+        this.addAttachmentClass(attachment)
 
         const container = this.config.container === false ? document.body : $(this.config.container)
 
-        $(tip)
-          .data(this.constructor.DATA_KEY, this)
-          .appendTo(container)
+        $(tip).data(this.constructor.DATA_KEY, this)
+
+        if (!$.contains(this.element.ownerDocument.documentElement, this.tip)) {
+          $(tip).appendTo(container)
+        }
 
         $(this.element).trigger(this.constructor.Event.INSERTED)
 
-        this._tether = new Tether({
-          attachment,
-          element         : tip,
-          target          : this.element,
-          classes         : TetherClass,
-          classPrefix     : CLASS_PREFIX,
-          offset          : this.config.offset,
-          constraints     : this.config.constraints,
-          addTargetClasses: false
+        this._popper = new Popper(this.element, tip, {
+          placement : attachment,
+          modifiers : {
+            offset : {
+              offset : this.config.offset
+            },
+            flip : {
+              behavior : this.config.fallbackPlacement
+            }
+          },
+          onCreate : (data) => {
+            if (data.originalPlacement !== data.placement) {
+              this._handlePopperPlacementChange(data)
+            }
+          },
+          onUpdate : (data) => {
+            this._handlePopperPlacementChange(data)
+          }
         })
 
-        Util.reflow(tip)
-        this._tether.position()
-
         $(tip).addClass(ClassName.SHOW)
 
+        // if this is a touch-enabled device we add extra
+        // empty mouseover listeners to the body's immediate children;
+        // only needed because of broken event delegation on iOS
+        // https://www.quirksmode.org/blog/archives/2014/02/mouse_event_bub.html
+        if ('ontouchstart' in document.documentElement) {
+          $('body').children().on('mouseover', null, $.noop)
+        }
+
         const complete = () => {
+          if (this.config.animation) {
+            this._fixTransition()
+          }
           const prevHoverState = this._hoverState
-          this._hoverState   = null
-          this._isTransitioning = false
+          this._hoverState     = null
 
           $(this.element).trigger(this.constructor.Event.SHOWN)
 
@@ -318,32 +332,29 @@ const Tooltip = (($) => {
         }
 
         if (Util.supportsTransitionEnd() && $(this.tip).hasClass(ClassName.FADE)) {
-          this._isTransitioning = true
           $(this.tip)
             .one(Util.TRANSITION_END, complete)
             .emulateTransitionEnd(Tooltip._TRANSITION_DURATION)
-          return
+        } else {
+          complete()
         }
-
-        complete()
       }
     }
 
     hide(callback) {
       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._cleanTipClass()
         this.element.removeAttribute('aria-describedby')
         $(this.element).trigger(this.constructor.Event.HIDDEN)
-        this._isTransitioning = false
-        this.cleanupTether()
+        if (this._popper !== null) {
+          this._popper.destroy()
+        }
 
         if (callback) {
           callback()
@@ -358,13 +369,19 @@ const Tooltip = (($) => {
 
       $(tip).removeClass(ClassName.SHOW)
 
+      // if this is a touch-enabled device we remove the extra
+      // empty mouseover listeners we added for iOS support
+      if ('ontouchstart' in document.documentElement) {
+        $('body').children().off('mouseover', null, $.noop)
+      }
+
       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
+
         $(tip)
           .one(Util.TRANSITION_END, complete)
           .emulateTransitionEnd(TRANSITION_DURATION)
@@ -374,8 +391,14 @@ const Tooltip = (($) => {
       }
 
       this._hoverState = ''
+
     }
 
+    update() {
+      if (this._popper !== null) {
+        this._popper.scheduleUpdate()
+      }
+    }
 
     // protected
 
@@ -383,18 +406,18 @@ const Tooltip = (($) => {
       return Boolean(this.getTitle())
     }
 
+    addAttachmentClass(attachment) {
+      $(this.getTipElement()).addClass(`${CLASS_PREFIX}-${attachment}`)
+    }
+
     getTipElement() {
       return this.tip = this.tip || $(this.config.template)[0]
     }
 
     setContent() {
       const $tip = $(this.getTipElement())
-
       this.setElementContent($tip.find(Selector.TOOLTIP_INNER), this.getTitle())
-
       $tip.removeClass(`${ClassName.FADE} ${ClassName.SHOW}`)
-
-      this.cleanupTether()
     }
 
     setElementContent($element, content) {
@@ -425,12 +448,6 @@ const Tooltip = (($) => {
       return title
     }
 
-    cleanupTether() {
-      if (this._tether) {
-        this._tether.destroy()
-      }
-    }
-
 
     // private
 
@@ -603,6 +620,14 @@ const Tooltip = (($) => {
         }
       }
 
+      if (config.title && typeof config.title === 'number') {
+        config.title = config.title.toString()
+      }
+
+      if (config.content && typeof config.content === 'number') {
+        config.content = config.content.toString()
+      }
+
       Util.typeCheckConfig(
         NAME,
         config,
@@ -626,6 +651,31 @@ const Tooltip = (($) => {
       return config
     }
 
+    _cleanTipClass() {
+      const $tip = $(this.getTipElement())
+      const tabClass = $tip.attr('class').match(BSCLS_PREFIX_REGEX)
+      if (tabClass !== null && tabClass.length > 0) {
+        $tip.removeClass(tabClass.join(''))
+      }
+    }
+
+    _handlePopperPlacementChange(data) {
+      this._cleanTipClass()
+      this.addAttachmentClass(this._getAttachment(data.placement))
+    }
+
+    _fixTransition() {
+      const tip                 = this.getTipElement()
+      const initConfigAnimation = this.config.animation
+      if (tip.getAttribute('x-placement') !== null) {
+        return
+      }
+      $(tip).removeClass(ClassName.FADE)
+      this.config.animation = false
+      this.hide()
+      this.show()
+      this.config.animation = initConfigAnimation
+    }
 
     // static
 
diff --git a/js/src/util.js b/js/src/util.js
index 06424fbfe..3c0d02251 100644
--- a/js/src/util.js
+++ b/js/src/util.js
@@ -1,6 +1,6 @@
 /**
  * --------------------------------------------------------------------------
- * Bootstrap (v4.0.0-alpha.5): util.js
+ * Bootstrap (v4.0.0-alpha.6): util.js
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  * --------------------------------------------------------------------------
  */
@@ -112,13 +112,16 @@ const Util = (($) => {
 
     getSelectorFromElement(element) {
       let selector = element.getAttribute('data-target')
-
-      if (!selector) {
+      if (!selector || selector === '#') {
         selector = element.getAttribute('href') || ''
-        selector = /^#[a-z]/i.test(selector) ? selector : null
       }
 
-      return selector
+      try {
+        const $selector = $(selector)
+        return $selector.length > 0 ? selector : null
+      } catch (error) {
+        return null
+      }
     },
 
     reflow(element) {