Switch to strings constants.

This allows the minifier to mangle the constants. It also allows the linter to find unused strings properly.

While at it, remove a few unused properties.

File                        Before      After       Diff
--------------------------------------------------------
bootstrap.bundle.min.js     23.61 kB    22.61 kB    -1.00 kB (-4.23 %)
bootstrap.min.js            17.04 kB    16.08 kB    -0.96 kB (-5.63 %)

11 files changed, 482 insertions, 556 deletions

diff --git a/js/src/alert.js b/js/src/alert.js
index dbd931b52e..6de3fa7f87 100644
--- a/js/src/alert.js
+++ b/js/src/alert.js
@@ -28,21 +28,15 @@ const DATA_KEY = 'bs.alert'
 const EVENT_KEY = `.${DATA_KEY}`
 const DATA_API_KEY = '.data-api'
 
-const Selector = {
-  DISMISS: '[data-dismiss="alert"]'
-}
+const SELECTOR_DISMISS = '[data-dismiss="alert"]'
 
-const Event = {
-  CLOSE: `close${EVENT_KEY}`,
-  CLOSED: `closed${EVENT_KEY}`,
-  CLICK_DATA_API: `click${EVENT_KEY}${DATA_API_KEY}`
-}
+const EVENT_CLOSE = `close${EVENT_KEY}`
+const EVENT_CLOSED = `closed${EVENT_KEY}`
+const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
 
-const ClassName = {
-  ALERT: 'alert',
-  FADE: 'fade',
-  SHOW: 'show'
-}
+const CLASSNAME_ALERT = 'alert'
+const CLASSNAME_FADE = 'fade'
+const CLASSNAME_SHOW = 'show'
 
 /**
  * ------------------------------------------------------------------------
@@ -93,20 +87,20 @@ class Alert {
     let parent = getElementFromSelector(element)
 
     if (!parent) {
-      parent = SelectorEngine.closest(element, `.${ClassName.ALERT}`)
+      parent = SelectorEngine.closest(element, `.${CLASSNAME_ALERT}`)
     }
 
     return parent
   }
 
   _triggerCloseEvent(element) {
-    return EventHandler.trigger(element, Event.CLOSE)
+    return EventHandler.trigger(element, EVENT_CLOSE)
   }
 
   _removeElement(element) {
-    element.classList.remove(ClassName.SHOW)
+    element.classList.remove(CLASSNAME_SHOW)
 
-    if (!element.classList.contains(ClassName.FADE)) {
+    if (!element.classList.contains(CLASSNAME_FADE)) {
       this._destroyElement(element)
       return
     }
@@ -123,7 +117,7 @@ class Alert {
       element.parentNode.removeChild(element)
     }
 
-    EventHandler.trigger(element, Event.CLOSED)
+    EventHandler.trigger(element, EVENT_CLOSED)
   }
 
   // Static
@@ -163,7 +157,7 @@ class Alert {
  * ------------------------------------------------------------------------
  */
 EventHandler
-  .on(document, Event.CLICK_DATA_API, Selector.DISMISS, Alert.handleDismiss(new Alert()))
+  .on(document, EVENT_CLICK_DATA_API, SELECTOR_DISMISS, Alert.handleDismiss(new Alert()))
 
 const $ = getjQuery()
 
diff --git a/js/src/button.js b/js/src/button.js
index 314d2a22a0..9c68862b21 100644
--- a/js/src/button.js
+++ b/js/src/button.js
@@ -22,26 +22,20 @@ const DATA_KEY = 'bs.button'
 const EVENT_KEY = `.${DATA_KEY}`
 const DATA_API_KEY = '.data-api'
 
-const ClassName = {
-  ACTIVE: 'active',
-  BUTTON: 'btn',
-  DISABLED: 'disabled',
-  FOCUS: 'focus'
-}
+const CLASS_NAME_ACTIVE = 'active'
+const CLASS_NAME_BUTTON = 'btn'
+const CLASS_NAME_DISABLED = 'disabled'
+const CLASS_NAME_FOCUS = 'focus'
 
-const Selector = {
-  DATA_TOGGLE_CARROT: '[data-toggle^="button"]',
-  DATA_TOGGLE: '[data-toggle="buttons"]',
-  INPUT: 'input:not([type="hidden"])',
-  ACTIVE: '.active',
-  BUTTON: '.btn'
-}
+const SELECTOR_DATA_TOGGLE_CARROT = '[data-toggle^="button"]'
+const SELECTOR_DATA_TOGGLE = '[data-toggle="buttons"]'
+const SELECTOR_INPUT = 'input:not([type="hidden"])'
+const SELECTOR_ACTIVE = '.active'
+const SELECTOR_BUTTON = '.btn'
 
-const Event = {
-  CLICK_DATA_API: `click${EVENT_KEY}${DATA_API_KEY}`,
-  FOCUS_DATA_API: `focus${EVENT_KEY}${DATA_API_KEY}`,
-  BLUR_DATA_API: `blur${EVENT_KEY}${DATA_API_KEY}`
-}
+const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
+const EVENT_FOCUS_DATA_API = `focus${EVENT_KEY}${DATA_API_KEY}`
+const EVENT_BLUR_DATA_API = `blur${EVENT_KEY}${DATA_API_KEY}`
 
 /**
  * ------------------------------------------------------------------------
@@ -69,33 +63,33 @@ class Button {
 
     const rootElement = SelectorEngine.closest(
       this._element,
-      Selector.DATA_TOGGLE
+      SELECTOR_DATA_TOGGLE
     )
 
     if (rootElement) {
-      const input = SelectorEngine.findOne(Selector.INPUT, this._element)
+      const input = SelectorEngine.findOne(SELECTOR_INPUT, this._element)
 
       if (input && input.type === 'radio') {
         if (input.checked &&
-          this._element.classList.contains(ClassName.ACTIVE)) {
+          this._element.classList.contains(CLASS_NAME_ACTIVE)) {
           triggerChangeEvent = false
         } else {
-          const activeElement = SelectorEngine.findOne(Selector.ACTIVE, rootElement)
+          const activeElement = SelectorEngine.findOne(SELECTOR_ACTIVE, rootElement)
 
           if (activeElement) {
-            activeElement.classList.remove(ClassName.ACTIVE)
+            activeElement.classList.remove(CLASS_NAME_ACTIVE)
           }
         }
 
         if (triggerChangeEvent) {
           if (input.hasAttribute('disabled') ||
             rootElement.hasAttribute('disabled') ||
-            input.classList.contains(ClassName.DISABLED) ||
-            rootElement.classList.contains(ClassName.DISABLED)) {
+            input.classList.contains(CLASS_NAME_DISABLED) ||
+            rootElement.classList.contains(CLASS_NAME_DISABLED)) {
             return
           }
 
-          input.checked = !this._element.classList.contains(ClassName.ACTIVE)
+          input.checked = !this._element.classList.contains(CLASS_NAME_ACTIVE)
           EventHandler.trigger(input, 'change')
         }
 
@@ -106,11 +100,11 @@ class Button {
 
     if (addAriaPressed) {
       this._element.setAttribute('aria-pressed',
-        !this._element.classList.contains(ClassName.ACTIVE))
+        !this._element.classList.contains(CLASS_NAME_ACTIVE))
     }
 
     if (triggerChangeEvent) {
-      this._element.classList.toggle(ClassName.ACTIVE)
+      this._element.classList.toggle(CLASS_NAME_ACTIVE)
     }
   }
 
@@ -146,12 +140,12 @@ class Button {
  * ------------------------------------------------------------------------
  */
 
-EventHandler.on(document, Event.CLICK_DATA_API, Selector.DATA_TOGGLE_CARROT, event => {
+EventHandler.on(document, EVENT_CLICK_DATA_API, SELECTOR_DATA_TOGGLE_CARROT, event => {
   event.preventDefault()
 
   let button = event.target
-  if (!button.classList.contains(ClassName.BUTTON)) {
-    button = SelectorEngine.closest(button, Selector.BUTTON)
+  if (!button.classList.contains(CLASS_NAME_BUTTON)) {
+    button = SelectorEngine.closest(button, SELECTOR_BUTTON)
   }
 
   let data = Data.getData(button, DATA_KEY)
@@ -162,19 +156,19 @@ EventHandler.on(document, Event.CLICK_DATA_API, Selector.DATA_TOGGLE_CARROT, eve
   data.toggle()
 })
 
-EventHandler.on(document, Event.FOCUS_DATA_API, Selector.DATA_TOGGLE_CARROT, event => {
-  const button = SelectorEngine.closest(event.target, Selector.BUTTON)
+EventHandler.on(document, EVENT_FOCUS_DATA_API, SELECTOR_DATA_TOGGLE_CARROT, event => {
+  const button = SelectorEngine.closest(event.target, SELECTOR_BUTTON)
 
   if (button) {
-    button.classList.add(ClassName.FOCUS)
+    button.classList.add(CLASS_NAME_FOCUS)
   }
 })
 
-EventHandler.on(document, Event.BLUR_DATA_API, Selector.DATA_TOGGLE_CARROT, event => {
-  const button = SelectorEngine.closest(event.target, Selector.BUTTON)
+EventHandler.on(document, EVENT_BLUR_DATA_API, SELECTOR_DATA_TOGGLE_CARROT, event => {
+  const button = SelectorEngine.closest(event.target, SELECTOR_BUTTON)
 
   if (button) {
-    button.classList.remove(ClassName.FOCUS)
+    button.classList.remove(CLASS_NAME_FOCUS)
   }
 })
 
diff --git a/js/src/carousel.js b/js/src/carousel.js
index 5034f17984..7230d5aaf7 100644
--- a/js/src/carousel.js
+++ b/js/src/carousel.js
@@ -33,6 +33,7 @@ const VERSION = '4.3.1'
 const DATA_KEY = 'bs.carousel'
 const EVENT_KEY = `.${DATA_KEY}`
 const DATA_API_KEY = '.data-api'
+
 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
@@ -56,51 +57,42 @@ const DefaultType = {
   touch: 'boolean'
 }
 
-const Direction = {
-  NEXT: 'next',
-  PREV: 'prev',
-  LEFT: 'left',
-  RIGHT: 'right'
-}
-
-const Event = {
-  SLIDE: `slide${EVENT_KEY}`,
-  SLID: `slid${EVENT_KEY}`,
-  KEYDOWN: `keydown${EVENT_KEY}`,
-  MOUSEENTER: `mouseenter${EVENT_KEY}`,
-  MOUSELEAVE: `mouseleave${EVENT_KEY}`,
-  TOUCHSTART: `touchstart${EVENT_KEY}`,
-  TOUCHMOVE: `touchmove${EVENT_KEY}`,
-  TOUCHEND: `touchend${EVENT_KEY}`,
-  POINTERDOWN: `pointerdown${EVENT_KEY}`,
-  POINTERUP: `pointerup${EVENT_KEY}`,
-  DRAG_START: `dragstart${EVENT_KEY}`,
-  LOAD_DATA_API: `load${EVENT_KEY}${DATA_API_KEY}`,
-  CLICK_DATA_API: `click${EVENT_KEY}${DATA_API_KEY}`
-}
-
-const ClassName = {
-  CAROUSEL: 'carousel',
-  ACTIVE: 'active',
-  SLIDE: 'slide',
-  RIGHT: 'carousel-item-right',
-  LEFT: 'carousel-item-left',
-  NEXT: 'carousel-item-next',
-  PREV: 'carousel-item-prev',
-  ITEM: 'carousel-item',
-  POINTER_EVENT: 'pointer-event'
-}
-
-const Selector = {
-  ACTIVE: '.active',
-  ACTIVE_ITEM: '.active.carousel-item',
-  ITEM: '.carousel-item',
-  ITEM_IMG: '.carousel-item img',
-  NEXT_PREV: '.carousel-item-next, .carousel-item-prev',
-  INDICATORS: '.carousel-indicators',
-  DATA_SLIDE: '[data-slide], [data-slide-to]',
-  DATA_RIDE: '[data-ride="carousel"]'
-}
+const DIRECTION_NEXT = 'next'
+const DIRECTION_PREV = 'prev'
+const DIRECTION_LEFT = 'left'
+const DIRECTION_RIGHT = 'right'
+
+const EVENT_SLIDE = `slide${EVENT_KEY}`
+const EVENT_SLID = `slid${EVENT_KEY}`
+const EVENT_KEYDOWN = `keydown${EVENT_KEY}`
+const EVENT_MOUSEENTER = `mouseenter${EVENT_KEY}`
+const EVENT_MOUSELEAVE = `mouseleave${EVENT_KEY}`
+const EVENT_TOUCHSTART = `touchstart${EVENT_KEY}`
+const EVENT_TOUCHMOVE = `touchmove${EVENT_KEY}`
+const EVENT_TOUCHEND = `touchend${EVENT_KEY}`
+const EVENT_POINTERDOWN = `pointerdown${EVENT_KEY}`
+const EVENT_POINTERUP = `pointerup${EVENT_KEY}`
+const EVENT_DRAG_START = `dragstart${EVENT_KEY}`
+const EVENT_LOAD_DATA_API = `load${EVENT_KEY}${DATA_API_KEY}`
+const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
+
+const CLASS_NAME_CAROUSEL = 'carousel'
+const CLASS_NAME_ACTIVE = 'active'
+const CLASS_NAME_SLIDE = 'slide'
+const CLASS_NAME_RIGHT = 'carousel-item-right'
+const CLASS_NAME_LEFT = 'carousel-item-left'
+const CLASS_NAME_NEXT = 'carousel-item-next'
+const CLASS_NAME_PREV = 'carousel-item-prev'
+const CLASS_NAME_POINTER_EVENT = 'pointer-event'
+
+const SELECTOR_ACTIVE = '.active'
+const SELECTOR_ACTIVE_ITEM = '.active.carousel-item'
+const SELECTOR_ITEM = '.carousel-item'
+const SELECTOR_ITEM_IMG = '.carousel-item img'
+const SELECTOR_NEXT_PREV = '.carousel-item-next, .carousel-item-prev'
+const SELECTOR_INDICATORS = '.carousel-indicators'
+const SELECTOR_DATA_SLIDE = '[data-slide], [data-slide-to]'
+const SELECTOR_DATA_RIDE = '[data-ride="carousel"]'
 
 const PointerType = {
   TOUCH: 'touch',
@@ -125,7 +117,7 @@ class Carousel {
 
     this._config = this._getConfig(config)
     this._element = element
-    this._indicatorsElement = SelectorEngine.findOne(Selector.INDICATORS, this._element)
+    this._indicatorsElement = SelectorEngine.findOne(SELECTOR_INDICATORS, this._element)
     this._touchSupported = 'ontouchstart' in document.documentElement || navigator.maxTouchPoints > 0
     this._pointerEvent = Boolean(window.PointerEvent || window.MSPointerEvent)
 
@@ -147,7 +139,7 @@ class Carousel {
 
   next() {
     if (!this._isSliding) {
-      this._slide(Direction.NEXT)
+      this._slide(DIRECTION_NEXT)
     }
   }
 
@@ -161,7 +153,7 @@ class Carousel {
 
   prev() {
     if (!this._isSliding) {
-      this._slide(Direction.PREV)
+      this._slide(DIRECTION_PREV)
     }
   }
 
@@ -170,7 +162,7 @@ class Carousel {
       this._isPaused = true
     }
 
-    if (SelectorEngine.findOne(Selector.NEXT_PREV, this._element)) {
+    if (SelectorEngine.findOne(SELECTOR_NEXT_PREV, this._element)) {
       triggerTransitionEnd(this._element)
       this.cycle(true)
     }
@@ -198,7 +190,7 @@ class Carousel {
   }
 
   to(index) {
-    this._activeElement = SelectorEngine.findOne(Selector.ACTIVE_ITEM, this._element)
+    this._activeElement = SelectorEngine.findOne(SELECTOR_ACTIVE_ITEM, this._element)
     const activeIndex = this._getItemIndex(this._activeElement)
 
     if (index > this._items.length - 1 || index < 0) {
@@ -206,7 +198,7 @@ class Carousel {
     }
 
     if (this._isSliding) {
-      EventHandler.one(this._element, Event.SLID, () => this.to(index))
+      EventHandler.one(this._element, EVENT_SLID, () => this.to(index))
       return
     }
 
@@ -217,8 +209,8 @@ class Carousel {
     }
 
     const direction = index > activeIndex ?
-      Direction.NEXT :
-      Direction.PREV
+      DIRECTION_NEXT :
+      DIRECTION_PREV
 
     this._slide(direction, this._items[index])
   }
@@ -273,14 +265,14 @@ class Carousel {
   _addEventListeners() {
     if (this._config.keyboard) {
       EventHandler
-        .on(this._element, Event.KEYDOWN, event => this._keydown(event))
+        .on(this._element, EVENT_KEYDOWN, event => this._keydown(event))
     }
 
     if (this._config.pause === 'hover') {
       EventHandler
-        .on(this._element, Event.MOUSEENTER, event => this.pause(event))
+        .on(this._element, EVENT_MOUSEENTER, event => this.pause(event))
       EventHandler
-        .on(this._element, Event.MOUSELEAVE, event => this.cycle(event))
+        .on(this._element, EVENT_MOUSELEAVE, event => this.cycle(event))
     }
 
     if (this._config.touch && this._touchSupported) {
@@ -330,19 +322,19 @@ class Carousel {
       }
     }
 
-    makeArray(SelectorEngine.find(Selector.ITEM_IMG, this._element)).forEach(itemImg => {
-      EventHandler.on(itemImg, Event.DRAG_START, e => e.preventDefault())
+    makeArray(SelectorEngine.find(SELECTOR_ITEM_IMG, this._element)).forEach(itemImg => {
+      EventHandler.on(itemImg, EVENT_DRAG_START, e => e.preventDefault())
     })
 
     if (this._pointerEvent) {
-      EventHandler.on(this._element, Event.POINTERDOWN, event => start(event))
-      EventHandler.on(this._element, Event.POINTERUP, event => end(event))
+      EventHandler.on(this._element, EVENT_POINTERDOWN, event => start(event))
+      EventHandler.on(this._element, EVENT_POINTERUP, event => end(event))
 
-      this._element.classList.add(ClassName.POINTER_EVENT)
+      this._element.classList.add(CLASS_NAME_POINTER_EVENT)
     } else {
-      EventHandler.on(this._element, Event.TOUCHSTART, event => start(event))
-      EventHandler.on(this._element, Event.TOUCHMOVE, event => move(event))
-      EventHandler.on(this._element, Event.TOUCHEND, event => end(event))
+      EventHandler.on(this._element, EVENT_TOUCHSTART, event => start(event))
+      EventHandler.on(this._element, EVENT_TOUCHMOVE, event => move(event))
+      EventHandler.on(this._element, EVENT_TOUCHEND, event => end(event))
     }
   }
 
@@ -366,15 +358,15 @@ class Carousel {
 
   _getItemIndex(element) {
     this._items = element && element.parentNode ?
-      makeArray(SelectorEngine.find(Selector.ITEM, element.parentNode)) :
+      makeArray(SelectorEngine.find(SELECTOR_ITEM, element.parentNode)) :
       []
 
     return this._items.indexOf(element)
   }
 
   _getItemByDirection(direction, activeElement) {
-    const isNextDirection = direction === Direction.NEXT
-    const isPrevDirection = direction === Direction.PREV
+    const isNextDirection = direction === DIRECTION_NEXT
+    const isPrevDirection = direction === DIRECTION_PREV
     const activeIndex = this._getItemIndex(activeElement)
     const lastItemIndex = this._items.length - 1
     const isGoingToWrap = (isPrevDirection && activeIndex === 0) ||
@@ -384,7 +376,7 @@ class Carousel {
       return activeElement
     }
 
-    const delta = direction === Direction.PREV ? -1 : 1
+    const delta = direction === DIRECTION_PREV ? -1 : 1
     const itemIndex = (activeIndex + delta) % this._items.length
 
     return itemIndex === -1 ?
@@ -394,9 +386,9 @@ class Carousel {
 
   _triggerSlideEvent(relatedTarget, eventDirectionName) {
     const targetIndex = this._getItemIndex(relatedTarget)
-    const fromIndex = this._getItemIndex(SelectorEngine.findOne(Selector.ACTIVE_ITEM, this._element))
+    const fromIndex = this._getItemIndex(SelectorEngine.findOne(SELECTOR_ACTIVE_ITEM, this._element))
 
-    return EventHandler.trigger(this._element, Event.SLIDE, {
+    return EventHandler.trigger(this._element, EVENT_SLIDE, {
       relatedTarget,
       direction: eventDirectionName,
       from: fromIndex,
@@ -406,9 +398,9 @@ class Carousel {
 
   _setActiveIndicatorElement(element) {
     if (this._indicatorsElement) {
-      const indicators = SelectorEngine.find(Selector.ACTIVE, this._indicatorsElement)
+      const indicators = SelectorEngine.find(SELECTOR_ACTIVE, this._indicatorsElement)
       for (let i = 0; i < indicators.length; i++) {
-        indicators[i].classList.remove(ClassName.ACTIVE)
+        indicators[i].classList.remove(CLASS_NAME_ACTIVE)
       }
 
       const nextIndicator = this._indicatorsElement.children[
@@ -416,13 +408,13 @@ class Carousel {
       ]
 
       if (nextIndicator) {
-        nextIndicator.classList.add(ClassName.ACTIVE)
+        nextIndicator.classList.add(CLASS_NAME_ACTIVE)
       }
     }
   }
 
   _slide(direction, element) {
-    const activeElement = SelectorEngine.findOne(Selector.ACTIVE_ITEM, this._element)
+    const activeElement = SelectorEngine.findOne(SELECTOR_ACTIVE_ITEM, this._element)
     const activeElementIndex = this._getItemIndex(activeElement)
     const nextElement = element || (activeElement &&
       this._getItemByDirection(direction, activeElement))
@@ -434,17 +426,17 @@ class Carousel {
     let orderClassName
     let eventDirectionName
 
-    if (direction === Direction.NEXT) {
-      directionalClassName = ClassName.LEFT
-      orderClassName = ClassName.NEXT
-      eventDirectionName = Direction.LEFT
+    if (direction === DIRECTION_NEXT) {
+      directionalClassName = CLASS_NAME_LEFT
+      orderClassName = CLASS_NAME_NEXT
+      eventDirectionName = DIRECTION_LEFT
     } else {
-      directionalClassName = ClassName.RIGHT
-      orderClassName = ClassName.PREV
-      eventDirectionName = Direction.RIGHT
+      directionalClassName = CLASS_NAME_RIGHT
+      orderClassName = CLASS_NAME_PREV
+      eventDirectionName = DIRECTION_RIGHT
     }
 
-    if (nextElement && nextElement.classList.contains(ClassName.ACTIVE)) {
+    if (nextElement && nextElement.classList.contains(CLASS_NAME_ACTIVE)) {
       this._isSliding = false
       return
     }
@@ -467,7 +459,7 @@ class Carousel {
 
     this._setActiveIndicatorElement(nextElement)
 
-    if (this._element.classList.contains(ClassName.SLIDE)) {
+    if (this._element.classList.contains(CLASS_NAME_SLIDE)) {
       nextElement.classList.add(orderClassName)
 
       reflow(nextElement)
@@ -489,16 +481,16 @@ class Carousel {
         .one(activeElement, TRANSITION_END, () => {
           nextElement.classList.remove(directionalClassName)
           nextElement.classList.remove(orderClassName)
-          nextElement.classList.add(ClassName.ACTIVE)
+          nextElement.classList.add(CLASS_NAME_ACTIVE)
 
-          activeElement.classList.remove(ClassName.ACTIVE)
+          activeElement.classList.remove(CLASS_NAME_ACTIVE)
           activeElement.classList.remove(orderClassName)
           activeElement.classList.remove(directionalClassName)
 
           this._isSliding = false
 
           setTimeout(() => {
-            EventHandler.trigger(this._element, Event.SLID, {
+            EventHandler.trigger(this._element, EVENT_SLID, {
               relatedTarget: nextElement,
               direction: eventDirectionName,
               from: activeElementIndex,
@@ -509,11 +501,11 @@ class Carousel {
 
       emulateTransitionEnd(activeElement, transitionDuration)
     } else {
-      activeElement.classList.remove(ClassName.ACTIVE)
-      nextElement.classList.add(ClassName.ACTIVE)
+      activeElement.classList.remove(CLASS_NAME_ACTIVE)
+      nextElement.classList.add(CLASS_NAME_ACTIVE)
 
       this._isSliding = false
-      EventHandler.trigger(this._element, Event.SLID, {
+      EventHandler.trigger(this._element, EVENT_SLID, {
         relatedTarget: nextElement,
         direction: eventDirectionName,
         from: activeElementIndex,
@@ -571,7 +563,7 @@ class Carousel {
   static dataApiClickHandler(event) {
     const target = getElementFromSelector(this)
 
-    if (!target || !target.classList.contains(ClassName.CAROUSEL)) {
+    if (!target || !target.classList.contains(CLASS_NAME_CAROUSEL)) {
       return
     }
 
@@ -606,10 +598,10 @@ class Carousel {
  */
 
 EventHandler
-  .on(document, Event.CLICK_DATA_API, Selector.DATA_SLIDE, Carousel.dataApiClickHandler)
+  .on(document, EVENT_CLICK_DATA_API, SELECTOR_DATA_SLIDE, Carousel.dataApiClickHandler)
 
-EventHandler.on(window, Event.LOAD_DATA_API, () => {
-  const carousels = makeArray(SelectorEngine.find(Selector.DATA_RIDE))
+EventHandler.on(window, EVENT_LOAD_DATA_API, () => {
+  const carousels = makeArray(SelectorEngine.find(SELECTOR_DATA_RIDE))
   for (let i = 0, len = carousels.length; i < len; i++) {
     Carousel.carouselInterface(carousels[i], Data.getData(carousels[i], DATA_KEY))
   }
diff --git a/js/src/collapse.js b/js/src/collapse.js
index 27eef4ef72..3b78c5cdb3 100644
--- a/js/src/collapse.js
+++ b/js/src/collapse.js
@@ -44,30 +44,22 @@ const DefaultType = {
   parent: '(string|element)'
 }
 
-const Event = {
-  SHOW: `show${EVENT_KEY}`,
-  SHOWN: `shown${EVENT_KEY}`,
-  HIDE: `hide${EVENT_KEY}`,
-  HIDDEN: `hidden${EVENT_KEY}`,
-  CLICK_DATA_API: `click${EVENT_KEY}${DATA_API_KEY}`
-}
+const EVENT_SHOW = `show${EVENT_KEY}`
+const EVENT_SHOWN = `shown${EVENT_KEY}`
+const EVENT_HIDE = `hide${EVENT_KEY}`
+const EVENT_HIDDEN = `hidden${EVENT_KEY}`
+const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
 
-const ClassName = {
-  SHOW: 'show',
-  COLLAPSE: 'collapse',
-  COLLAPSING: 'collapsing',
-  COLLAPSED: 'collapsed'
-}
+const CLASS_NAME_SHOW = 'show'
+const CLASS_NAME_COLLAPSE = 'collapse'
+const CLASS_NAME_COLLAPSING = 'collapsing'
+const CLASS_NAME_COLLAPSED = 'collapsed'
 
-const Dimension = {
-  WIDTH: 'width',
-  HEIGHT: 'height'
-}
+const WIDTH = 'width'
+const HEIGHT = 'height'
 
-const Selector = {
-  ACTIVES: '.show, .collapsing',
-  DATA_TOGGLE: '[data-toggle="collapse"]'
-}
+const SELECTOR_ACTIVES = '.show, .collapsing'
+const SELECTOR_DATA_TOGGLE = '[data-toggle="collapse"]'
 
 /**
  * ------------------------------------------------------------------------
@@ -81,11 +73,11 @@ class Collapse {
     this._element = element
     this._config = this._getConfig(config)
     this._triggerArray = makeArray(SelectorEngine.find(
-      `${Selector.DATA_TOGGLE}[href="#${element.id}"],` +
-      `${Selector.DATA_TOGGLE}[data-target="#${element.id}"]`
+      `${SELECTOR_DATA_TOGGLE}[href="#${element.id}"],` +
+      `${SELECTOR_DATA_TOGGLE}[data-target="#${element.id}"]`
     ))
 
-    const toggleList = makeArray(SelectorEngine.find(Selector.DATA_TOGGLE))
+    const toggleList = makeArray(SelectorEngine.find(SELECTOR_DATA_TOGGLE))
     for (let i = 0, len = toggleList.length; i < len; i++) {
       const elem = toggleList[i]
       const selector = getSelectorFromElement(elem)
@@ -124,7 +116,7 @@ class Collapse {
   // Public
 
   toggle() {
-    if (this._element.classList.contains(ClassName.SHOW)) {
+    if (this._element.classList.contains(CLASS_NAME_SHOW)) {
       this.hide()
     } else {
       this.show()
@@ -133,7 +125,7 @@ class Collapse {
 
   show() {
     if (this._isTransitioning ||
-      this._element.classList.contains(ClassName.SHOW)) {
+      this._element.classList.contains(CLASS_NAME_SHOW)) {
       return
     }
 
@@ -141,13 +133,13 @@ class Collapse {
     let activesData
 
     if (this._parent) {
-      actives = makeArray(SelectorEngine.find(Selector.ACTIVES, this._parent))
+      actives = makeArray(SelectorEngine.find(SELECTOR_ACTIVES, this._parent))
         .filter(elem => {
           if (typeof this._config.parent === 'string') {
             return elem.getAttribute('data-parent') === this._config.parent
           }
 
-          return elem.classList.contains(ClassName.COLLAPSE)
+          return elem.classList.contains(CLASS_NAME_COLLAPSE)
         })
 
       if (actives.length === 0) {
@@ -165,7 +157,7 @@ class Collapse {
       }
     }
 
-    const startEvent = EventHandler.trigger(this._element, Event.SHOW)
+    const startEvent = EventHandler.trigger(this._element, EVENT_SHOW)
     if (startEvent.defaultPrevented) {
       return
     }
@@ -184,14 +176,14 @@ class Collapse {
 
     const dimension = this._getDimension()
 
-    this._element.classList.remove(ClassName.COLLAPSE)
-    this._element.classList.add(ClassName.COLLAPSING)
+    this._element.classList.remove(CLASS_NAME_COLLAPSE)
+    this._element.classList.add(CLASS_NAME_COLLAPSING)
 
     this._element.style[dimension] = 0
 
     if (this._triggerArray.length) {
       this._triggerArray.forEach(element => {
-        element.classList.remove(ClassName.COLLAPSED)
+        element.classList.remove(CLASS_NAME_COLLAPSED)
         element.setAttribute('aria-expanded', true)
       })
     }
@@ -199,15 +191,15 @@ class Collapse {
     this.setTransitioning(true)
 
     const complete = () => {
-      this._element.classList.remove(ClassName.COLLAPSING)
-      this._element.classList.add(ClassName.COLLAPSE)
-      this._element.classList.add(ClassName.SHOW)
+      this._element.classList.remove(CLASS_NAME_COLLAPSING)
+      this._element.classList.add(CLASS_NAME_COLLAPSE)
+      this._element.classList.add(CLASS_NAME_SHOW)
 
       this._element.style[dimension] = ''
 
       this.setTransitioning(false)
 
-      EventHandler.trigger(this._element, Event.SHOWN)
+      EventHandler.trigger(this._element, EVENT_SHOWN)
     }
 
     const capitalizedDimension = dimension[0].toUpperCase() + dimension.slice(1)
@@ -222,11 +214,11 @@ class Collapse {
 
   hide() {
     if (this._isTransitioning ||
-      !this._element.classList.contains(ClassName.SHOW)) {
+      !this._element.classList.contains(CLASS_NAME_SHOW)) {
       return
     }
 
-    const startEvent = EventHandler.trigger(this._element, Event.HIDE)
+    const startEvent = EventHandler.trigger(this._element, EVENT_HIDE)
     if (startEvent.defaultPrevented) {
       return
     }
@@ -237,9 +229,9 @@ class Collapse {
 
     reflow(this._element)
 
-    this._element.classList.add(ClassName.COLLAPSING)
-    this._element.classList.remove(ClassName.COLLAPSE)
-    this._element.classList.remove(ClassName.SHOW)
+    this._element.classList.add(CLASS_NAME_COLLAPSING)
+    this._element.classList.remove(CLASS_NAME_COLLAPSE)
+    this._element.classList.remove(CLASS_NAME_SHOW)
 
     const triggerArrayLength = this._triggerArray.length
     if (triggerArrayLength > 0) {
@@ -247,8 +239,8 @@ class Collapse {
         const trigger = this._triggerArray[i]
         const elem = getElementFromSelector(trigger)
 
-        if (elem && !elem.classList.contains(ClassName.SHOW)) {
-          trigger.classList.add(ClassName.COLLAPSED)
+        if (elem && !elem.classList.contains(CLASS_NAME_SHOW)) {
+          trigger.classList.add(CLASS_NAME_COLLAPSED)
           trigger.setAttribute('aria-expanded', false)
         }
       }
@@ -258,9 +250,9 @@ class Collapse {
 
     const complete = () => {
       this.setTransitioning(false)
-      this._element.classList.remove(ClassName.COLLAPSING)
-      this._element.classList.add(ClassName.COLLAPSE)
-      EventHandler.trigger(this._element, Event.HIDDEN)
+      this._element.classList.remove(CLASS_NAME_COLLAPSING)
+      this._element.classList.add(CLASS_NAME_COLLAPSE)
+      EventHandler.trigger(this._element, EVENT_HIDDEN)
     }
 
     this._element.style[dimension] = ''
@@ -297,8 +289,8 @@ class Collapse {
   }
 
   _getDimension() {
-    const hasWidth = this._element.classList.contains(Dimension.WIDTH)
-    return hasWidth ? Dimension.WIDTH : Dimension.HEIGHT
+    const hasWidth = this._element.classList.contains(WIDTH)
+    return hasWidth ? WIDTH : HEIGHT
   }
 
   _getParent() {
@@ -313,7 +305,7 @@ class Collapse {
       parent = SelectorEngine.findOne(parent)
     }
 
-    const selector = `${Selector.DATA_TOGGLE}[data-parent="${parent}"]`
+    const selector = `${SELECTOR_DATA_TOGGLE}[data-parent="${parent}"]`
 
     makeArray(SelectorEngine.find(selector, parent))
       .forEach(element => {
@@ -330,14 +322,14 @@ class Collapse {
 
   _addAriaAndCollapsedClass(element, triggerArray) {
     if (element) {
-      const isOpen = element.classList.contains(ClassName.SHOW)
+      const isOpen = element.classList.contains(CLASS_NAME_SHOW)
 
       if (triggerArray.length) {
         triggerArray.forEach(elem => {
           if (isOpen) {
-            elem.classList.remove(ClassName.COLLAPSED)
+            elem.classList.remove(CLASS_NAME_COLLAPSED)
           } else {
-            elem.classList.add(ClassName.COLLAPSED)
+            elem.classList.add(CLASS_NAME_COLLAPSED)
           }
 
           elem.setAttribute('aria-expanded', isOpen)
@@ -390,7 +382,7 @@ class Collapse {
  * ------------------------------------------------------------------------
  */
 
-EventHandler.on(document, Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
+EventHandler.on(document, EVENT_CLICK_DATA_API, SELECTOR_DATA_TOGGLE, function (event) {
   // preventDefault only for <a> elements (which change the URL) not inside the collapsible element
   if (event.target.tagName === 'A') {
     event.preventDefault()
diff --git a/js/src/dropdown.js b/js/src/dropdown.js
index 82a24405aa..9d6f8a3296 100644
--- a/js/src/dropdown.js
+++ b/js/src/dropdown.js
@@ -31,54 +31,46 @@ const VERSION = '4.3.1'
 const DATA_KEY = 'bs.dropdown'
 const EVENT_KEY = `.${DATA_KEY}`
 const DATA_API_KEY = '.data-api'
+
 const ESCAPE_KEYCODE = 27 // KeyboardEvent.which value for Escape (Esc) key
 const SPACE_KEYCODE = 32 // KeyboardEvent.which value for space key
 const TAB_KEYCODE = 9 // KeyboardEvent.which value for tab key
 const ARROW_UP_KEYCODE = 38 // KeyboardEvent.which value for up arrow key
 const ARROW_DOWN_KEYCODE = 40 // KeyboardEvent.which value for down arrow key
 const RIGHT_MOUSE_BUTTON_WHICH = 3 // MouseEvent.which value for the right button (assuming a right-handed mouse)
-const REGEXP_KEYDOWN = new RegExp(`${ARROW_UP_KEYCODE}|${ARROW_DOWN_KEYCODE}|${ESCAPE_KEYCODE}`)
 
-const Event = {
-  HIDE: `hide${EVENT_KEY}`,
-  HIDDEN: `hidden${EVENT_KEY}`,
-  SHOW: `show${EVENT_KEY}`,
-  SHOWN: `shown${EVENT_KEY}`,
-  CLICK: `click${EVENT_KEY}`,
-  CLICK_DATA_API: `click${EVENT_KEY}${DATA_API_KEY}`,
-  KEYDOWN_DATA_API: `keydown${EVENT_KEY}${DATA_API_KEY}`,
-  KEYUP_DATA_API: `keyup${EVENT_KEY}${DATA_API_KEY}`
-}
-
-const ClassName = {
-  DISABLED: 'disabled',
-  SHOW: 'show',
-  DROPUP: 'dropup',
-  DROPRIGHT: 'dropright',
-  DROPLEFT: 'dropleft',
-  MENURIGHT: 'dropdown-menu-right',
-  NAVBAR: 'navbar',
-  POSITION_STATIC: 'position-static'
-}
-
-const Selector = {
-  DATA_TOGGLE: '[data-toggle="dropdown"]',
-  FORM_CHILD: '.dropdown form',
-  MENU: '.dropdown-menu',
-  NAVBAR_NAV: '.navbar-nav',
-  VISIBLE_ITEMS: '.dropdown-menu .dropdown-item:not(.disabled):not(:disabled)'
-}
+const REGEXP_KEYDOWN = new RegExp(`${ARROW_UP_KEYCODE}|${ARROW_DOWN_KEYCODE}|${ESCAPE_KEYCODE}`)
 
-const AttachmentMap = {
-  TOP: 'top-start',
-  TOPEND: 'top-end',
-  BOTTOM: 'bottom-start',
-  BOTTOMEND: 'bottom-end',
-  RIGHT: 'right-start',
-  RIGHTEND: 'right-end',
-  LEFT: 'left-start',
-  LEFTEND: 'left-end'
-}
+const EVENT_HIDE = `hide${EVENT_KEY}`
+const EVENT_HIDDEN = `hidden${EVENT_KEY}`
+const EVENT_SHOW = `show${EVENT_KEY}`
+const EVENT_SHOWN = `shown${EVENT_KEY}`
+const EVENT_CLICK = `click${EVENT_KEY}`
+const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
+const EVENT_KEYDOWN_DATA_API = `keydown${EVENT_KEY}${DATA_API_KEY}`
+const EVENT_KEYUP_DATA_API = `keyup${EVENT_KEY}${DATA_API_KEY}`
+
+const CLASS_NAME_DISABLED = 'disabled'
+const CLASS_NAME_SHOW = 'show'
+const CLASS_NAME_DROPUP = 'dropup'
+const CLASS_NAME_DROPRIGHT = 'dropright'
+const CLASS_NAME_DROPLEFT = 'dropleft'
+const CLASS_NAME_MENURIGHT = 'dropdown-menu-right'
+const CLASS_NAME_NAVBAR = 'navbar'
+const CLASS_NAME_POSITION_STATIC = 'position-static'
+
+const SELECTOR_DATA_TOGGLE = '[data-toggle="dropdown"]'
+const SELECTOR_FORM_CHILD = '.dropdown form'
+const SELECTOR_MENU = '.dropdown-menu'
+const SELECTOR_NAVBAR_NAV = '.navbar-nav'
+const SELECTOR_VISIBLE_ITEMS = '.dropdown-menu .dropdown-item:not(.disabled):not(:disabled)'
+
+const PLACEMENT_TOP = 'top-start'
+const PLACEMENT_TOPEND = 'top-end'
+const PLACEMENT_BOTTOM = 'bottom-start'
+const PLACEMENT_BOTTOMEND = 'bottom-end'
+const PLACEMENT_RIGHT = 'right-start'
+const PLACEMENT_LEFT = 'left-start'
 
 const Default = {
   offset: 0,
@@ -133,11 +125,11 @@ class Dropdown {
   // Public
 
   toggle() {
-    if (this._element.disabled || this._element.classList.contains(ClassName.DISABLED)) {
+    if (this._element.disabled || this._element.classList.contains(CLASS_NAME_DISABLED)) {
       return
     }
 
-    const isActive = this._menu.classList.contains(ClassName.SHOW)
+    const isActive = this._menu.classList.contains(CLASS_NAME_SHOW)
 
     Dropdown.clearMenus()
 
@@ -149,7 +141,7 @@ class Dropdown {
   }
 
   show() {
-    if (this._element.disabled || this._element.classList.contains(ClassName.DISABLED) || this._menu.classList.contains(ClassName.SHOW)) {
+    if (this._element.disabled || this._element.classList.contains(CLASS_NAME_DISABLED) || this._menu.classList.contains(CLASS_NAME_SHOW)) {
       return
     }
 
@@ -158,7 +150,7 @@ class Dropdown {
       relatedTarget: this._element
     }
 
-    const showEvent = EventHandler.trigger(parent, Event.SHOW, relatedTarget)
+    const showEvent = EventHandler.trigger(parent, EVENT_SHOW, relatedTarget)
 
     if (showEvent.defaultPrevented) {
       return
@@ -187,7 +179,7 @@ class Dropdown {
       // to allow the menu to "escape" the scroll parent's boundaries
       // https://github.com/twbs/bootstrap/issues/24251
       if (this._config.boundary !== 'scrollParent') {
-        parent.classList.add(ClassName.POSITION_STATIC)
+        parent.classList.add(CLASS_NAME_POSITION_STATIC)
       }
 
       this._popper = new Popper(referenceElement, this._menu, this._getPopperConfig())
@@ -198,7 +190,7 @@ class Dropdown {
     // 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 &&
-      !makeArray(SelectorEngine.closest(parent, Selector.NAVBAR_NAV)).length) {
+      !makeArray(SelectorEngine.closest(parent, SELECTOR_NAVBAR_NAV)).length) {
       makeArray(document.body.children)
         .forEach(elem => EventHandler.on(elem, 'mouseover', null, noop()))
     }
@@ -206,13 +198,13 @@ class Dropdown {
     this._element.focus()
     this._element.setAttribute('aria-expanded', true)
 
-    Manipulator.toggleClass(this._menu, ClassName.SHOW)
-    Manipulator.toggleClass(parent, ClassName.SHOW)
-    EventHandler.trigger(parent, Event.SHOWN, relatedTarget)
+    Manipulator.toggleClass(this._menu, CLASS_NAME_SHOW)
+    Manipulator.toggleClass(parent, CLASS_NAME_SHOW)
+    EventHandler.trigger(parent, EVENT_SHOWN, relatedTarget)
   }
 
   hide() {
-    if (this._element.disabled || this._element.classList.contains(ClassName.DISABLED) || !this._menu.classList.contains(ClassName.SHOW)) {
+    if (this._element.disabled || this._element.classList.contains(CLASS_NAME_DISABLED) || !this._menu.classList.contains(CLASS_NAME_SHOW)) {
       return
     }
 
@@ -221,7 +213,7 @@ class Dropdown {
       relatedTarget: this._element
     }
 
-    const hideEvent = EventHandler.trigger(parent, Event.HIDE, relatedTarget)
+    const hideEvent = EventHandler.trigger(parent, EVENT_HIDE, relatedTarget)
 
     if (hideEvent.defaultPrevented) {
       return
@@ -231,9 +223,9 @@ class Dropdown {
       this._popper.destroy()
     }
 
-    Manipulator.toggleClass(this._menu, ClassName.SHOW)
-    Manipulator.toggleClass(parent, ClassName.SHOW)
-    EventHandler.trigger(parent, Event.HIDDEN, relatedTarget)
+    Manipulator.toggleClass(this._menu, CLASS_NAME_SHOW)
+    Manipulator.toggleClass(parent, CLASS_NAME_SHOW)
+    EventHandler.trigger(parent, EVENT_HIDDEN, relatedTarget)
   }
 
   dispose() {
@@ -257,7 +249,7 @@ class Dropdown {
   // Private
 
   _addEventListeners() {
-    EventHandler.on(this._element, Event.CLICK, event => {
+    EventHandler.on(this._element, EVENT_CLICK, event => {
       event.preventDefault()
       event.stopPropagation()
       this.toggle()
@@ -283,32 +275,32 @@ class Dropdown {
   _getMenuElement() {
     const parent = Dropdown.getParentFromElement(this._element)
 
-    return SelectorEngine.findOne(Selector.MENU, parent)
+    return SelectorEngine.findOne(SELECTOR_MENU, parent)
   }
 
   _getPlacement() {
     const parentDropdown = this._element.parentNode
-    let placement = AttachmentMap.BOTTOM
+    let placement = PLACEMENT_BOTTOM
 
     // Handle dropup
-    if (parentDropdown.classList.contains(ClassName.DROPUP)) {
-      placement = AttachmentMap.TOP
-      if (this._menu.classList.contains(ClassName.MENURIGHT)) {
-        placement = AttachmentMap.TOPEND
+    if (parentDropdown.classList.contains(CLASS_NAME_DROPUP)) {
+      placement = PLACEMENT_TOP
+      if (this._menu.classList.contains(CLASS_NAME_MENURIGHT)) {
+        placement = PLACEMENT_TOPEND
       }
-    } else if (parentDropdown.classList.contains(ClassName.DROPRIGHT)) {
-      placement = AttachmentMap.RIGHT
-    } else if (parentDropdown.classList.contains(ClassName.DROPLEFT)) {
-      placement = AttachmentMap.LEFT
-    } else if (this._menu.classList.contains(ClassName.MENURIGHT)) {
-      placement = AttachmentMap.BOTTOMEND
+    } else if (parentDropdown.classList.contains(CLASS_NAME_DROPRIGHT)) {
+      placement = PLACEMENT_RIGHT
+    } else if (parentDropdown.classList.contains(CLASS_NAME_DROPLEFT)) {
+      placement = PLACEMENT_LEFT
+    } else if (this._menu.classList.contains(CLASS_NAME_MENURIGHT)) {
+      placement = PLACEMENT_BOTTOMEND
     }
 
     return placement
   }
 
   _detectNavbar() {
-    return Boolean(SelectorEngine.closest(this._element, `.${ClassName.NAVBAR}`))
+    return Boolean(SelectorEngine.closest(this._element, `.${CLASS_NAME_NAVBAR}`))
   }
 
   _getOffset() {
@@ -388,7 +380,7 @@ class Dropdown {
       return
     }
 
-    const toggles = makeArray(SelectorEngine.find(Selector.DATA_TOGGLE))
+    const toggles = makeArray(SelectorEngine.find(SELECTOR_DATA_TOGGLE))
     for (let i = 0, len = toggles.length; i < len; i++) {
       const parent = Dropdown.getParentFromElement(toggles[i])
       const context = Data.getData(toggles[i], DATA_KEY)
@@ -405,7 +397,7 @@ class Dropdown {
       }
 
       const dropdownMenu = context._menu
-      if (!parent.classList.contains(ClassName.SHOW)) {
+      if (!parent.classList.contains(CLASS_NAME_SHOW)) {
         continue
       }
 
@@ -416,7 +408,7 @@ class Dropdown {
         continue
       }
 
-      const hideEvent = EventHandler.trigger(parent, Event.HIDE, relatedTarget)
+      const hideEvent = EventHandler.trigger(parent, EVENT_HIDE, relatedTarget)
       if (hideEvent.defaultPrevented) {
         continue
       }
@@ -434,9 +426,9 @@ class Dropdown {
         context._popper.destroy()
       }
 
-      dropdownMenu.classList.remove(ClassName.SHOW)
-      parent.classList.remove(ClassName.SHOW)
-      EventHandler.trigger(parent, Event.HIDDEN, relatedTarget)
+      dropdownMenu.classList.remove(CLASS_NAME_SHOW)
+      parent.classList.remove(CLASS_NAME_SHOW)
+      EventHandler.trigger(parent, EVENT_HIDDEN, relatedTarget)
     }
   }
 
@@ -455,7 +447,7 @@ class Dropdown {
     if (/input|textarea/i.test(event.target.tagName) ?
       event.which === SPACE_KEYCODE || (event.which !== ESCAPE_KEYCODE &&
       ((event.which !== ARROW_DOWN_KEYCODE && event.which !== ARROW_UP_KEYCODE) ||
-        SelectorEngine.closest(event.target, Selector.MENU))) :
+        SelectorEngine.closest(event.target, SELECTOR_MENU))) :
       !REGEXP_KEYDOWN.test(event.which)) {
       return
     }
@@ -463,23 +455,23 @@ class Dropdown {
     event.preventDefault()
     event.stopPropagation()
 
-    if (this.disabled || this.classList.contains(ClassName.DISABLED)) {
+    if (this.disabled || this.classList.contains(CLASS_NAME_DISABLED)) {
       return
     }
 
     const parent = Dropdown.getParentFromElement(this)
-    const isActive = parent.classList.contains(ClassName.SHOW)
+    const isActive = parent.classList.contains(CLASS_NAME_SHOW)
 
     if (!isActive || (isActive && (event.which === ESCAPE_KEYCODE || event.which === SPACE_KEYCODE))) {
       if (event.which === ESCAPE_KEYCODE) {
-        SelectorEngine.findOne(Selector.DATA_TOGGLE, parent).focus()
+        SelectorEngine.findOne(SELECTOR_DATA_TOGGLE, parent).focus()
       }
 
       Dropdown.clearMenus()
       return
     }
 
-    const items = makeArray(SelectorEngine.find(Selector.VISIBLE_ITEMS, parent))
+    const items = makeArray(SelectorEngine.find(SELECTOR_VISIBLE_ITEMS, parent))
       .filter(isVisible)
 
     if (!items.length) {
@@ -514,17 +506,17 @@ class Dropdown {
  * ------------------------------------------------------------------------
  */
 
-EventHandler.on(document, Event.KEYDOWN_DATA_API, Selector.DATA_TOGGLE, Dropdown.dataApiKeydownHandler)
-EventHandler.on(document, Event.KEYDOWN_DATA_API, Selector.MENU, Dropdown.dataApiKeydownHandler)
-EventHandler.on(document, Event.CLICK_DATA_API, Dropdown.clearMenus)
-EventHandler.on(document, Event.KEYUP_DATA_API, Dropdown.clearMenus)
-EventHandler.on(document, Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
+EventHandler.on(document, EVENT_KEYDOWN_DATA_API, SELECTOR_DATA_TOGGLE, Dropdown.dataApiKeydownHandler)
+EventHandler.on(document, EVENT_KEYDOWN_DATA_API, SELECTOR_MENU, Dropdown.dataApiKeydownHandler)
+EventHandler.on(document, EVENT_CLICK_DATA_API, Dropdown.clearMenus)
+EventHandler.on(document, EVENT_KEYUP_DATA_API, Dropdown.clearMenus)
+EventHandler.on(document, EVENT_CLICK_DATA_API, SELECTOR_DATA_TOGGLE, function (event) {
   event.preventDefault()
   event.stopPropagation()
   Dropdown.dropdownInterface(this, 'toggle')
 })
 EventHandler
-  .on(document, Event.CLICK_DATA_API, Selector.FORM_CHILD, e => e.stopPropagation())
+  .on(document, EVENT_CLICK_DATA_API, SELECTOR_FORM_CHILD, e => e.stopPropagation())
 
 const $ = getjQuery()
 
diff --git a/js/src/modal.js b/js/src/modal.js
index 48ff5b8540..bcf13454fe 100644
--- a/js/src/modal.js
+++ b/js/src/modal.js
@@ -48,39 +48,33 @@ const DefaultType = {
   show: 'boolean'
 }
 
-const Event = {
-  HIDE: `hide${EVENT_KEY}`,
-  HIDE_PREVENTED: `hidePrevented${EVENT_KEY}`,
-  HIDDEN: `hidden${EVENT_KEY}`,
-  SHOW: `show${EVENT_KEY}`,
-  SHOWN: `shown${EVENT_KEY}`,
-  FOCUSIN: `focusin${EVENT_KEY}`,
-  RESIZE: `resize${EVENT_KEY}`,
-  CLICK_DISMISS: `click.dismiss${EVENT_KEY}`,
-  KEYDOWN_DISMISS: `keydown.dismiss${EVENT_KEY}`,
-  MOUSEUP_DISMISS: `mouseup.dismiss${EVENT_KEY}`,
-  MOUSEDOWN_DISMISS: `mousedown.dismiss${EVENT_KEY}`,
-  CLICK_DATA_API: `click${EVENT_KEY}${DATA_API_KEY}`
-}
-
-const ClassName = {
-  SCROLLABLE: 'modal-dialog-scrollable',
-  SCROLLBAR_MEASURER: 'modal-scrollbar-measure',
-  BACKDROP: 'modal-backdrop',
-  OPEN: 'modal-open',
-  FADE: 'fade',
-  SHOW: 'show',
-  STATIC: 'modal-static'
-}
-
-const Selector = {
-  DIALOG: '.modal-dialog',
-  MODAL_BODY: '.modal-body',
-  DATA_TOGGLE: '[data-toggle="modal"]',
-  DATA_DISMISS: '[data-dismiss="modal"]',
-  FIXED_CONTENT: '.fixed-top, .fixed-bottom, .is-fixed, .sticky-top',
-  STICKY_CONTENT: '.sticky-top'
-}
+const EVENT_HIDE = `hide${EVENT_KEY}`
+const EVENT_HIDE_PREVENTED = `hidePrevented${EVENT_KEY}`
+const EVENT_HIDDEN = `hidden${EVENT_KEY}`
+const EVENT_SHOW = `show${EVENT_KEY}`
+const EVENT_SHOWN = `shown${EVENT_KEY}`
+const EVENT_FOCUSIN = `focusin${EVENT_KEY}`
+const EVENT_RESIZE = `resize${EVENT_KEY}`
+const EVENT_CLICK_DISMISS = `click.dismiss${EVENT_KEY}`
+const EVENT_KEYDOWN_DISMISS = `keydown.dismiss${EVENT_KEY}`
+const EVENT_MOUSEUP_DISMISS = `mouseup.dismiss${EVENT_KEY}`
+const EVENT_MOUSEDOWN_DISMISS = `mousedown.dismiss${EVENT_KEY}`
+const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
+
+const CLASS_NAME_SCROLLABLE = 'modal-dialog-scrollable'
+const CLASS_NAME_SCROLLBAR_MEASURER = 'modal-scrollbar-measure'
+const CLASS_NAME_BACKDROP = 'modal-backdrop'
+const CLASS_NAME_OPEN = 'modal-open'
+const CLASS_NAME_FADE = 'fade'
+const CLASS_NAME_SHOW = 'show'
+const CLASS_NAME_STATIC = 'modal-static'
+
+const SELECTOR_DIALOG = '.modal-dialog'
+const SELECTOR_MODAL_BODY = '.modal-body'
+const SELECTOR_DATA_TOGGLE = '[data-toggle="modal"]'
+const SELECTOR_DATA_DISMISS = '[data-dismiss="modal"]'
+const SELECTOR_FIXED_CONTENT = '.fixed-top, .fixed-bottom, .is-fixed, .sticky-top'
+const SELECTOR_STICKY_CONTENT = '.sticky-top'
 
 /**
  * ------------------------------------------------------------------------
@@ -92,7 +86,7 @@ class Modal {
   constructor(element, config) {
     this._config = this._getConfig(config)
     this._element = element
-    this._dialog = SelectorEngine.findOne(Selector.DIALOG, element)
+    this._dialog = SelectorEngine.findOne(SELECTOR_DIALOG, element)
     this._backdrop = null
     this._isShown = false
     this._isBodyOverflowing = false
@@ -123,11 +117,11 @@ class Modal {
       return
     }
 
-    if (this._element.classList.contains(ClassName.FADE)) {
+    if (this._element.classList.contains(CLASS_NAME_FADE)) {
       this._isTransitioning = true
     }
 
-    const showEvent = EventHandler.trigger(this._element, Event.SHOW, {
+    const showEvent = EventHandler.trigger(this._element, EVENT_SHOW, {
       relatedTarget
     })
 
@@ -146,13 +140,13 @@ class Modal {
     this._setResizeEvent()
 
     EventHandler.on(this._element,
-      Event.CLICK_DISMISS,
-      Selector.DATA_DISMISS,
+      EVENT_CLICK_DISMISS,
+      SELECTOR_DATA_DISMISS,
       event => this.hide(event)
     )
 
-    EventHandler.on(this._dialog, Event.MOUSEDOWN_DISMISS, () => {
-      EventHandler.one(this._element, Event.MOUSEUP_DISMISS, event => {
+    EventHandler.on(this._dialog, EVENT_MOUSEDOWN_DISMISS, () => {
+      EventHandler.one(this._element, EVENT_MOUSEUP_DISMISS, event => {
         if (event.target === this._element) {
           this._ignoreBackdropClick = true
         }
@@ -171,14 +165,14 @@ class Modal {
       return
     }
 
-    const hideEvent = EventHandler.trigger(this._element, Event.HIDE)
+    const hideEvent = EventHandler.trigger(this._element, EVENT_HIDE)
 
     if (hideEvent.defaultPrevented) {
       return
     }
 
     this._isShown = false
-    const transition = this._element.classList.contains(ClassName.FADE)
+    const transition = this._element.classList.contains(CLASS_NAME_FADE)
 
     if (transition) {
       this._isTransitioning = true
@@ -187,12 +181,12 @@ class Modal {
     this._setEscapeEvent()
     this._setResizeEvent()
 
-    EventHandler.off(document, Event.FOCUSIN)
+    EventHandler.off(document, EVENT_FOCUSIN)
 
-    this._element.classList.remove(ClassName.SHOW)
+    this._element.classList.remove(CLASS_NAME_SHOW)
 
-    EventHandler.off(this._element, Event.CLICK_DISMISS)
-    EventHandler.off(this._dialog, Event.MOUSEDOWN_DISMISS)
+    EventHandler.off(this._element, EVENT_CLICK_DISMISS)
+    EventHandler.off(this._dialog, EVENT_MOUSEDOWN_DISMISS)
 
     if (transition) {
       const transitionDuration = getTransitionDurationFromElement(this._element)
@@ -209,11 +203,11 @@ class Modal {
       .forEach(htmlElement => EventHandler.off(htmlElement, EVENT_KEY))
 
     /**
-     * `document` has 2 events `Event.FOCUSIN` and `Event.CLICK_DATA_API`
+     * `document` has 2 events `EVENT_FOCUSIN` and `EVENT_CLICK_DATA_API`
      * Do not move `document` in `htmlElements` array
-     * It will remove `Event.CLICK_DATA_API` event that should remain
+     * It will remove `EVENT_CLICK_DATA_API` event that should remain
      */
-    EventHandler.off(document, Event.FOCUSIN)
+    EventHandler.off(document, EVENT_FOCUSIN)
 
     Data.removeData(this._element, DATA_KEY)
 
@@ -244,8 +238,8 @@ class Modal {
   }
 
   _showElement(relatedTarget) {
-    const transition = this._element.classList.contains(ClassName.FADE)
-    const modalBody = SelectorEngine.findOne(Selector.MODAL_BODY, this._dialog)
+    const transition = this._element.classList.contains(CLASS_NAME_FADE)
+    const modalBody = SelectorEngine.findOne(SELECTOR_MODAL_BODY, this._dialog)
 
     if (!this._element.parentNode ||
         this._element.parentNode.nodeType !== Node.ELEMENT_NODE) {
@@ -257,7 +251,7 @@ class Modal {
     this._element.removeAttribute('aria-hidden')
     this._element.setAttribute('aria-modal', true)
 
-    if (this._dialog.classList.contains(ClassName.SCROLLABLE) && modalBody) {
+    if (this._dialog.classList.contains(CLASS_NAME_SCROLLABLE) && modalBody) {
       modalBody.scrollTop = 0
     } else {
       this._element.scrollTop = 0
@@ -267,7 +261,7 @@ class Modal {
       reflow(this._element)
     }
 
-    this._element.classList.add(ClassName.SHOW)
+    this._element.classList.add(CLASS_NAME_SHOW)
 
     if (this._config.focus) {
       this._enforceFocus()
@@ -279,7 +273,7 @@ class Modal {
       }
 
       this._isTransitioning = false
-      EventHandler.trigger(this._element, Event.SHOWN, {
+      EventHandler.trigger(this._element, EVENT_SHOWN, {
         relatedTarget
       })
     }
@@ -295,8 +289,8 @@ class Modal {
   }
 
   _enforceFocus() {
-    EventHandler.off(document, Event.FOCUSIN) // guard against infinite focus loop
-    EventHandler.on(document, Event.FOCUSIN, event => {
+    EventHandler.off(document, EVENT_FOCUSIN) // guard against infinite focus loop
+    EventHandler.on(document, EVENT_FOCUSIN, event => {
       if (document !== event.target &&
           this._element !== event.target &&
           !this._element.contains(event.target)) {
@@ -307,7 +301,7 @@ class Modal {
 
   _setEscapeEvent() {
     if (this._isShown) {
-      EventHandler.on(this._element, Event.KEYDOWN_DISMISS, event => {
+      EventHandler.on(this._element, EVENT_KEYDOWN_DISMISS, event => {
         if (this._config.keyboard && event.which === ESCAPE_KEYCODE) {
           event.preventDefault()
           this.hide()
@@ -316,15 +310,15 @@ class Modal {
         }
       })
     } else {
-      EventHandler.off(this._element, Event.KEYDOWN_DISMISS)
+      EventHandler.off(this._element, EVENT_KEYDOWN_DISMISS)
     }
   }
 
   _setResizeEvent() {
     if (this._isShown) {
-      EventHandler.on(window, Event.RESIZE, () => this._adjustDialog())
+      EventHandler.on(window, EVENT_RESIZE, () => this._adjustDialog())
     } else {
-      EventHandler.off(window, Event.RESIZE)
+      EventHandler.off(window, EVENT_RESIZE)
     }
   }
 
@@ -334,10 +328,10 @@ class Modal {
     this._element.removeAttribute('aria-modal')
     this._isTransitioning = false
     this._showBackdrop(() => {
-      document.body.classList.remove(ClassName.OPEN)
+      document.body.classList.remove(CLASS_NAME_OPEN)
       this._resetAdjustments()
       this._resetScrollbar()
-      EventHandler.trigger(this._element, Event.HIDDEN)
+      EventHandler.trigger(this._element, EVENT_HIDDEN)
     })
   }
 
@@ -347,13 +341,13 @@ class Modal {
   }
 
   _showBackdrop(callback) {
-    const animate = this._element.classList.contains(ClassName.FADE) ?
-      ClassName.FADE :
+    const animate = this._element.classList.contains(CLASS_NAME_FADE) ?
+      CLASS_NAME_FADE :
       ''
 
     if (this._isShown && this._config.backdrop) {
       this._backdrop = document.createElement('div')
-      this._backdrop.className = ClassName.BACKDROP
+      this._backdrop.className = CLASS_NAME_BACKDROP
 
       if (animate) {
         this._backdrop.classList.add(animate)
@@ -361,7 +355,7 @@ class Modal {
 
       document.body.appendChild(this._backdrop)
 
-      EventHandler.on(this._element, Event.CLICK_DISMISS, event => {
+      EventHandler.on(this._element, EVENT_CLICK_DISMISS, event => {
         if (this._ignoreBackdropClick) {
           this._ignoreBackdropClick = false
           return
@@ -378,7 +372,7 @@ class Modal {
         reflow(this._backdrop)
       }
 
-      this._backdrop.classList.add(ClassName.SHOW)
+      this._backdrop.classList.add(CLASS_NAME_SHOW)
 
       if (!animate) {
         callback()
@@ -390,14 +384,14 @@ class Modal {
       EventHandler.one(this._backdrop, TRANSITION_END, callback)
       emulateTransitionEnd(this._backdrop, backdropTransitionDuration)
     } else if (!this._isShown && this._backdrop) {
-      this._backdrop.classList.remove(ClassName.SHOW)
+      this._backdrop.classList.remove(CLASS_NAME_SHOW)
 
       const callbackRemove = () => {
         this._removeBackdrop()
         callback()
       }
 
-      if (this._element.classList.contains(ClassName.FADE)) {
+      if (this._element.classList.contains(CLASS_NAME_FADE)) {
         const backdropTransitionDuration = getTransitionDurationFromElement(this._backdrop)
         EventHandler.one(this._backdrop, TRANSITION_END, callbackRemove)
         emulateTransitionEnd(this._backdrop, backdropTransitionDuration)
@@ -411,15 +405,15 @@ class Modal {
 
   _triggerBackdropTransition() {
     if (this._config.backdrop === 'static') {
-      const hideEvent = EventHandler.trigger(this._element, Event.HIDE_PREVENTED)
+      const hideEvent = EventHandler.trigger(this._element, EVENT_HIDE_PREVENTED)
       if (hideEvent.defaultPrevented) {
         return
       }
 
-      this._element.classList.add(ClassName.STATIC)
+      this._element.classList.add(CLASS_NAME_STATIC)
       const modalTransitionDuration = getTransitionDurationFromElement(this._element)
       EventHandler.one(this._element, TRANSITION_END, () => {
-        this._element.classList.remove(ClassName.STATIC)
+        this._element.classList.remove(CLASS_NAME_STATIC)
       })
       emulateTransitionEnd(this._element, modalTransitionDuration)
       this._element.focus()
@@ -462,7 +456,7 @@ class Modal {
       //   while $(DOMNode).css('padding-right') returns the calculated value or 0 if not set
 
       // Adjust fixed content padding
-      makeArray(SelectorEngine.find(Selector.FIXED_CONTENT))
+      makeArray(SelectorEngine.find(SELECTOR_FIXED_CONTENT))
         .forEach(element => {
           const actualPadding = element.style.paddingRight
           const calculatedPadding = window.getComputedStyle(element)['padding-right']
@@ -471,7 +465,7 @@ class Modal {
         })
 
       // Adjust sticky content margin
-      makeArray(SelectorEngine.find(Selector.STICKY_CONTENT))
+      makeArray(SelectorEngine.find(SELECTOR_STICKY_CONTENT))
         .forEach(element => {
           const actualMargin = element.style.marginRight
           const calculatedMargin = window.getComputedStyle(element)['margin-right']
@@ -487,12 +481,12 @@ class Modal {
       document.body.style.paddingRight = `${parseFloat(calculatedPadding) + this._scrollbarWidth}px`
     }
 
-    document.body.classList.add(ClassName.OPEN)
+    document.body.classList.add(CLASS_NAME_OPEN)
   }
 
   _resetScrollbar() {
     // Restore fixed content padding
-    makeArray(SelectorEngine.find(Selector.FIXED_CONTENT))
+    makeArray(SelectorEngine.find(SELECTOR_FIXED_CONTENT))
       .forEach(element => {
         const padding = Manipulator.getDataAttribute(element, 'padding-right')
         if (typeof padding !== 'undefined') {
@@ -502,7 +496,7 @@ class Modal {
       })
 
     // Restore sticky content and navbar-toggler margin
-    makeArray(SelectorEngine.find(`${Selector.STICKY_CONTENT}`))
+    makeArray(SelectorEngine.find(`${SELECTOR_STICKY_CONTENT}`))
       .forEach(element => {
         const margin = Manipulator.getDataAttribute(element, 'margin-right')
         if (typeof margin !== 'undefined') {
@@ -523,7 +517,7 @@ class Modal {
 
   _getScrollbarWidth() { // thx d.walsh
     const scrollDiv = document.createElement('div')
-    scrollDiv.className = ClassName.SCROLLBAR_MEASURER
+    scrollDiv.className = CLASS_NAME_SCROLLBAR_MEASURER
     document.body.appendChild(scrollDiv)
     const scrollbarWidth = scrollDiv.getBoundingClientRect().width - scrollDiv.clientWidth
     document.body.removeChild(scrollDiv)
@@ -568,20 +562,20 @@ class Modal {
  * ------------------------------------------------------------------------
  */
 
-EventHandler.on(document, Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
+EventHandler.on(document, EVENT_CLICK_DATA_API, SELECTOR_DATA_TOGGLE, function (event) {
   const target = getElementFromSelector(this)
 
   if (this.tagName === 'A' || this.tagName === 'AREA') {
     event.preventDefault()
   }
 
-  EventHandler.one(target, Event.SHOW, showEvent => {
+  EventHandler.one(target, EVENT_SHOW, showEvent => {
     if (showEvent.defaultPrevented) {
       // only register focus restorer if modal will actually get shown
       return
     }
 
-    EventHandler.one(target, Event.HIDDEN, () => {
+    EventHandler.one(target, EVENT_HIDDEN, () => {
       if (isVisible(this)) {
         this.focus()
       }
diff --git a/js/src/popover.js b/js/src/popover.js
index d71a78236c..2d423f0dd5 100644
--- a/js/src/popover.js
+++ b/js/src/popover.js
@@ -39,16 +39,6 @@ const DefaultType = {
   content: '(string|element|function)'
 }
 
-const ClassName = {
-  FADE: 'fade',
-  SHOW: 'show'
-}
-
-const Selector = {
-  TITLE: '.popover-header',
-  CONTENT: '.popover-body'
-}
-
 const Event = {
   HIDE: `hide${EVENT_KEY}`,
   HIDDEN: `hidden${EVENT_KEY}`,
@@ -62,6 +52,12 @@ const Event = {
   MOUSELEAVE: `mouseleave${EVENT_KEY}`
 }
 
+const CLASS_NAME_FADE = 'fade'
+const CLASS_NAME_SHOW = 'show'
+
+const SELECTOR_TITLE = '.popover-header'
+const SELECTOR_CONTENT = '.popover-body'
+
 /**
  * ------------------------------------------------------------------------
  * Class Definition
@@ -109,16 +105,16 @@ class Popover extends Tooltip {
     const tip = this.getTipElement()
 
     // we use append for html objects to maintain js events
-    this.setElementContent(SelectorEngine.findOne(Selector.TITLE, tip), this.getTitle())
+    this.setElementContent(SelectorEngine.findOne(SELECTOR_TITLE, tip), this.getTitle())
     let content = this._getContent()
     if (typeof content === 'function') {
       content = content.call(this.element)
     }
 
-    this.setElementContent(SelectorEngine.findOne(Selector.CONTENT, tip), content)
+    this.setElementContent(SelectorEngine.findOne(SELECTOR_CONTENT, tip), content)
 
-    tip.classList.remove(ClassName.FADE)
-    tip.classList.remove(ClassName.SHOW)
+    tip.classList.remove(CLASS_NAME_FADE)
+    tip.classList.remove(CLASS_NAME_SHOW)
   }
 
   _addAttachmentClass(attachment) {
diff --git a/js/src/scrollspy.js b/js/src/scrollspy.js
index c379c62235..dd68ed386e 100644
--- a/js/src/scrollspy.js
+++ b/js/src/scrollspy.js
@@ -41,31 +41,23 @@ const DefaultType = {
   target: '(string|element)'
 }
 
-const Event = {
-  ACTIVATE: `activate${EVENT_KEY}`,
-  SCROLL: `scroll${EVENT_KEY}`,
-  LOAD_DATA_API: `load${EVENT_KEY}${DATA_API_KEY}`
-}
+const EVENT_ACTIVATE = `activate${EVENT_KEY}`
+const EVENT_SCROLL = `scroll${EVENT_KEY}`
+const EVENT_LOAD_DATA_API = `load${EVENT_KEY}${DATA_API_KEY}`
 
-const ClassName = {
-  DROPDOWN_ITEM: 'dropdown-item',
-  ACTIVE: 'active'
-}
+const CLASS_NAME_DROPDOWN_ITEM = 'dropdown-item'
+const CLASS_NAME_ACTIVE = 'active'
 
-const Selector = {
-  DATA_SPY: '[data-spy="scroll"]',
-  NAV_LIST_GROUP: '.nav, .list-group',
-  NAV_LINKS: '.nav-link',
-  NAV_ITEMS: '.nav-item',
-  LIST_ITEMS: '.list-group-item',
-  DROPDOWN: '.dropdown',
-  DROPDOWN_TOGGLE: '.dropdown-toggle'
-}
+const SELECTOR_DATA_SPY = '[data-spy="scroll"]'
+const SELECTOR_NAV_LIST_GROUP = '.nav, .list-group'
+const SELECTOR_NAV_LINKS = '.nav-link'
+const SELECTOR_NAV_ITEMS = '.nav-item'
+const SELECTOR_LIST_ITEMS = '.list-group-item'
+const SELECTOR_DROPDOWN = '.dropdown'
+const SELECTOR_DROPDOWN_TOGGLE = '.dropdown-toggle'
 
-const OffsetMethod = {
-  OFFSET: 'offset',
-  POSITION: 'position'
-}
+const METHOD_OFFSET = 'offset'
+const METHOD_POSITION = 'position'
 
 /**
  * ------------------------------------------------------------------------
@@ -78,15 +70,15 @@ class ScrollSpy {
     this._element = element
     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} .${ClassName.DROPDOWN_ITEM}`
+    this._selector = `${this._config.target} ${SELECTOR_NAV_LINKS},` +
+                          `${this._config.target} ${SELECTOR_LIST_ITEMS},` +
+                          `${this._config.target} .${CLASS_NAME_DROPDOWN_ITEM}`
     this._offsets = []
     this._targets = []
     this._activeTarget = null
     this._scrollHeight = 0
 
-    EventHandler.on(this._scrollElement, Event.SCROLL, event => this._process(event))
+    EventHandler.on(this._scrollElement, EVENT_SCROLL, event => this._process(event))
 
     this.refresh()
     this._process()
@@ -108,14 +100,14 @@ class ScrollSpy {
 
   refresh() {
     const autoMethod = this._scrollElement === this._scrollElement.window ?
-      OffsetMethod.OFFSET :
-      OffsetMethod.POSITION
+      METHOD_OFFSET :
+      METHOD_POSITION
 
     const offsetMethod = this._config.method === 'auto' ?
       autoMethod :
       this._config.method
 
-    const offsetBase = offsetMethod === OffsetMethod.POSITION ?
+    const offsetBase = offsetMethod === METHOD_POSITION ?
       this._getScrollTop() :
       0
 
@@ -261,42 +253,42 @@ class ScrollSpy {
 
     const link = SelectorEngine.findOne(queries.join(','))
 
-    if (link.classList.contains(ClassName.DROPDOWN_ITEM)) {
+    if (link.classList.contains(CLASS_NAME_DROPDOWN_ITEM)) {
       SelectorEngine
-        .findOne(Selector.DROPDOWN_TOGGLE, SelectorEngine.closest(link, Selector.DROPDOWN))
-        .classList.add(ClassName.ACTIVE)
+        .findOne(SELECTOR_DROPDOWN_TOGGLE, SelectorEngine.closest(link, SELECTOR_DROPDOWN))
+        .classList.add(CLASS_NAME_ACTIVE)
 
-      link.classList.add(ClassName.ACTIVE)
+      link.classList.add(CLASS_NAME_ACTIVE)
     } else {
       // Set triggered link as active
-      link.classList.add(ClassName.ACTIVE)
+      link.classList.add(CLASS_NAME_ACTIVE)
 
       SelectorEngine
-        .parents(link, Selector.NAV_LIST_GROUP)
+        .parents(link, SELECTOR_NAV_LIST_GROUP)
         .forEach(listGroup => {
           // Set triggered links parents as active
           // With both <ul> and <nav> markup a parent is the previous sibling of any nav ancestor
-          SelectorEngine.prev(listGroup, `${Selector.NAV_LINKS}, ${Selector.LIST_ITEMS}`)
-            .forEach(item => item.classList.add(ClassName.ACTIVE))
+          SelectorEngine.prev(listGroup, `${SELECTOR_NAV_LINKS}, ${SELECTOR_LIST_ITEMS}`)
+            .forEach(item => item.classList.add(CLASS_NAME_ACTIVE))
 
           // Handle special case when .nav-link is inside .nav-item
-          SelectorEngine.prev(listGroup, Selector.NAV_ITEMS)
+          SelectorEngine.prev(listGroup, SELECTOR_NAV_ITEMS)
             .forEach(navItem => {
-              SelectorEngine.children(navItem, Selector.NAV_LINKS)
-                .forEach(item => item.classList.add(ClassName.ACTIVE))
+              SelectorEngine.children(navItem, SELECTOR_NAV_LINKS)
+                .forEach(item => item.classList.add(CLASS_NAME_ACTIVE))
             })
         })
     }
 
-    EventHandler.trigger(this._scrollElement, Event.ACTIVATE, {
+    EventHandler.trigger(this._scrollElement, EVENT_ACTIVATE, {
       relatedTarget: target
     })
   }
 
   _clear() {
     makeArray(SelectorEngine.find(this._selector))
-      .filter(node => node.classList.contains(ClassName.ACTIVE))
-      .forEach(node => node.classList.remove(ClassName.ACTIVE))
+      .filter(node => node.classList.contains(CLASS_NAME_ACTIVE))
+      .forEach(node => node.classList.remove(CLASS_NAME_ACTIVE))
   }
 
   // Static
@@ -331,8 +323,8 @@ class ScrollSpy {
  * ------------------------------------------------------------------------
  */
 
-EventHandler.on(window, Event.LOAD_DATA_API, () => {
-  makeArray(SelectorEngine.find(Selector.DATA_SPY))
+EventHandler.on(window, EVENT_LOAD_DATA_API, () => {
+  makeArray(SelectorEngine.find(SELECTOR_DATA_SPY))
     .forEach(spy => new ScrollSpy(spy, Manipulator.getDataAttributes(spy)))
 })
 
diff --git a/js/src/tab.js b/js/src/tab.js
index d9bd1fc050..f7ec299466 100644
--- a/js/src/tab.js
+++ b/js/src/tab.js
@@ -30,31 +30,25 @@ const DATA_KEY = 'bs.tab'
 const EVENT_KEY = `.${DATA_KEY}`
 const DATA_API_KEY = '.data-api'
 
-const Event = {
-  HIDE: `hide${EVENT_KEY}`,
-  HIDDEN: `hidden${EVENT_KEY}`,
-  SHOW: `show${EVENT_KEY}`,
-  SHOWN: `shown${EVENT_KEY}`,
-  CLICK_DATA_API: `click${EVENT_KEY}${DATA_API_KEY}`
-}
-
-const ClassName = {
-  DROPDOWN_MENU: 'dropdown-menu',
-  ACTIVE: 'active',
-  DISABLED: 'disabled',
-  FADE: 'fade',
-  SHOW: 'show'
-}
-
-const Selector = {
-  DROPDOWN: '.dropdown',
-  NAV_LIST_GROUP: '.nav, .list-group',
-  ACTIVE: '.active',
-  ACTIVE_UL: ':scope > li > .active',
-  DATA_TOGGLE: '[data-toggle="tab"], [data-toggle="pill"], [data-toggle="list"]',
-  DROPDOWN_TOGGLE: '.dropdown-toggle',
-  DROPDOWN_ACTIVE_CHILD: ':scope > .dropdown-menu .active'
-}
+const EVENT_HIDE = `hide${EVENT_KEY}`
+const EVENT_HIDDEN = `hidden${EVENT_KEY}`
+const EVENT_SHOW = `show${EVENT_KEY}`
+const EVENT_SHOWN = `shown${EVENT_KEY}`
+const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
+
+const CLASS_NAME_DROPDOWN_MENU = 'dropdown-menu'
+const CLASS_NAME_ACTIVE = 'active'
+const CLASS_NAME_DISABLED = 'disabled'
+const CLASS_NAME_FADE = 'fade'
+const CLASS_NAME_SHOW = 'show'
+
+const SELECTOR_DROPDOWN = '.dropdown'
+const SELECTOR_NAV_LIST_GROUP = '.nav, .list-group'
+const SELECTOR_ACTIVE = '.active'
+const SELECTOR_ACTIVE_UL = ':scope > li > .active'
+const SELECTOR_DATA_TOGGLE = '[data-toggle="tab"], [data-toggle="pill"], [data-toggle="list"]'
+const SELECTOR_DROPDOWN_TOGGLE = '.dropdown-toggle'
+const SELECTOR_DROPDOWN_ACTIVE_CHILD = ':scope > .dropdown-menu .active'
 
 /**
  * ------------------------------------------------------------------------
@@ -80,17 +74,17 @@ class Tab {
   show() {
     if ((this._element.parentNode &&
       this._element.parentNode.nodeType === Node.ELEMENT_NODE &&
-      this._element.classList.contains(ClassName.ACTIVE)) ||
-      this._element.classList.contains(ClassName.DISABLED)) {
+      this._element.classList.contains(CLASS_NAME_ACTIVE)) ||
+      this._element.classList.contains(CLASS_NAME_DISABLED)) {
       return
     }
 
     let previous
     const target = getElementFromSelector(this._element)
-    const listElement = SelectorEngine.closest(this._element, Selector.NAV_LIST_GROUP)
+    const listElement = SelectorEngine.closest(this._element, SELECTOR_NAV_LIST_GROUP)
 
     if (listElement) {
-      const itemSelector = listElement.nodeName === 'UL' || listElement.nodeName === 'OL' ? Selector.ACTIVE_UL : Selector.ACTIVE
+      const itemSelector = listElement.nodeName === 'UL' || listElement.nodeName === 'OL' ? SELECTOR_ACTIVE_UL : SELECTOR_ACTIVE
       previous = makeArray(SelectorEngine.find(itemSelector, listElement))
       previous = previous[previous.length - 1]
     }
@@ -98,12 +92,12 @@ class Tab {
     let hideEvent = null
 
     if (previous) {
-      hideEvent = EventHandler.trigger(previous, Event.HIDE, {
+      hideEvent = EventHandler.trigger(previous, EVENT_HIDE, {
         relatedTarget: this._element
       })
     }
 
-    const showEvent = EventHandler.trigger(this._element, Event.SHOW, {
+    const showEvent = EventHandler.trigger(this._element, EVENT_SHOW, {
       relatedTarget: previous
     })
 
@@ -118,10 +112,10 @@ class Tab {
     )
 
     const complete = () => {
-      EventHandler.trigger(previous, Event.HIDDEN, {
+      EventHandler.trigger(previous, EVENT_HIDDEN, {
         relatedTarget: this._element
       })
-      EventHandler.trigger(this._element, Event.SHOWN, {
+      EventHandler.trigger(this._element, EVENT_SHOWN, {
         relatedTarget: previous
       })
     }
@@ -142,12 +136,12 @@ class Tab {
 
   _activate(element, container, callback) {
     const activeElements = container && (container.nodeName === 'UL' || container.nodeName === 'OL') ?
-      SelectorEngine.find(Selector.ACTIVE_UL, container) :
-      SelectorEngine.children(container, Selector.ACTIVE)
+      SelectorEngine.find(SELECTOR_ACTIVE_UL, container) :
+      SelectorEngine.children(container, SELECTOR_ACTIVE)
 
     const active = activeElements[0]
     const isTransitioning = callback &&
-      (active && active.classList.contains(ClassName.FADE))
+      (active && active.classList.contains(CLASS_NAME_FADE))
 
     const complete = () => this._transitionComplete(
       element,
@@ -157,7 +151,7 @@ class Tab {
 
     if (active && isTransitioning) {
       const transitionDuration = getTransitionDurationFromElement(active)
-      active.classList.remove(ClassName.SHOW)
+      active.classList.remove(CLASS_NAME_SHOW)
 
       EventHandler.one(active, TRANSITION_END, complete)
       emulateTransitionEnd(active, transitionDuration)
@@ -168,12 +162,12 @@ class Tab {
 
   _transitionComplete(element, active, callback) {
     if (active) {
-      active.classList.remove(ClassName.ACTIVE)
+      active.classList.remove(CLASS_NAME_ACTIVE)
 
-      const dropdownChild = SelectorEngine.findOne(Selector.DROPDOWN_ACTIVE_CHILD, active.parentNode)
+      const dropdownChild = SelectorEngine.findOne(SELECTOR_DROPDOWN_ACTIVE_CHILD, active.parentNode)
 
       if (dropdownChild) {
-        dropdownChild.classList.remove(ClassName.ACTIVE)
+        dropdownChild.classList.remove(CLASS_NAME_ACTIVE)
       }
 
       if (active.getAttribute('role') === 'tab') {
@@ -181,23 +175,23 @@ class Tab {
       }
     }
 
-    element.classList.add(ClassName.ACTIVE)
+    element.classList.add(CLASS_NAME_ACTIVE)
     if (element.getAttribute('role') === 'tab') {
       element.setAttribute('aria-selected', true)
     }
 
     reflow(element)
 
-    if (element.classList.contains(ClassName.FADE)) {
-      element.classList.add(ClassName.SHOW)
+    if (element.classList.contains(CLASS_NAME_FADE)) {
+      element.classList.add(CLASS_NAME_SHOW)
     }
 
-    if (element.parentNode && element.parentNode.classList.contains(ClassName.DROPDOWN_MENU)) {
-      const dropdownElement = SelectorEngine.closest(element, Selector.DROPDOWN)
+    if (element.parentNode && element.parentNode.classList.contains(CLASS_NAME_DROPDOWN_MENU)) {
+      const dropdownElement = SelectorEngine.closest(element, SELECTOR_DROPDOWN)
 
       if (dropdownElement) {
-        makeArray(SelectorEngine.find(Selector.DROPDOWN_TOGGLE))
-          .forEach(dropdown => dropdown.classList.add(ClassName.ACTIVE))
+        makeArray(SelectorEngine.find(SELECTOR_DROPDOWN_TOGGLE))
+          .forEach(dropdown => dropdown.classList.add(CLASS_NAME_ACTIVE))
       }
 
       element.setAttribute('aria-expanded', true)
@@ -235,7 +229,7 @@ class Tab {
  * ------------------------------------------------------------------------
  */
 
-EventHandler.on(document, Event.CLICK_DATA_API, Selector.DATA_TOGGLE, function (event) {
+EventHandler.on(document, EVENT_CLICK_DATA_API, SELECTOR_DATA_TOGGLE, function (event) {
   event.preventDefault()
 
   const data = Data.getData(this, DATA_KEY) || new Tab(this)
diff --git a/js/src/toast.js b/js/src/toast.js
index e0d2a8b3f2..abb0ffd341 100644
--- a/js/src/toast.js
+++ b/js/src/toast.js
@@ -28,20 +28,16 @@ const VERSION = '4.3.1'
 const DATA_KEY = 'bs.toast'
 const EVENT_KEY = `.${DATA_KEY}`
 
-const Event = {
-  CLICK_DISMISS: `click.dismiss${EVENT_KEY}`,
-  HIDE: `hide${EVENT_KEY}`,
-  HIDDEN: `hidden${EVENT_KEY}`,
-  SHOW: `show${EVENT_KEY}`,
-  SHOWN: `shown${EVENT_KEY}`
-}
+const EVENT_CLICK_DISMISS = `click.dismiss${EVENT_KEY}`
+const EVENT_HIDE = `hide${EVENT_KEY}`
+const EVENT_HIDDEN = `hidden${EVENT_KEY}`
+const EVENT_SHOW = `show${EVENT_KEY}`
+const EVENT_SHOWN = `shown${EVENT_KEY}`
 
-const ClassName = {
-  FADE: 'fade',
-  HIDE: 'hide',
-  SHOW: 'show',
-  SHOWING: 'showing'
-}
+const CLASS_NAME_FADE = 'fade'
+const CLASS_NAME_HIDE = 'hide'
+const CLASS_NAME_SHOW = 'show'
+const CLASS_NAME_SHOWING = 'showing'
 
 const DefaultType = {
   animation: 'boolean',
@@ -55,9 +51,7 @@ const Default = {
   delay: 500
 }
 
-const Selector = {
-  DATA_DISMISS: '[data-dismiss="toast"]'
-}
+const SELECTOR_DATA_DISMISS = '[data-dismiss="toast"]'
 
 /**
  * ------------------------------------------------------------------------
@@ -91,21 +85,21 @@ class Toast {
   // Public
 
   show() {
-    const showEvent = EventHandler.trigger(this._element, Event.SHOW)
+    const showEvent = EventHandler.trigger(this._element, EVENT_SHOW)
 
     if (showEvent.defaultPrevented) {
       return
     }
 
     if (this._config.animation) {
-      this._element.classList.add(ClassName.FADE)
+      this._element.classList.add(CLASS_NAME_FADE)
     }
 
     const complete = () => {
-      this._element.classList.remove(ClassName.SHOWING)
-      this._element.classList.add(ClassName.SHOW)
+      this._element.classList.remove(CLASS_NAME_SHOWING)
+      this._element.classList.add(CLASS_NAME_SHOW)
 
-      EventHandler.trigger(this._element, Event.SHOWN)
+      EventHandler.trigger(this._element, EVENT_SHOWN)
 
       if (this._config.autohide) {
         this._timeout = setTimeout(() => {
@@ -114,9 +108,9 @@ class Toast {
       }
     }
 
-    this._element.classList.remove(ClassName.HIDE)
+    this._element.classList.remove(CLASS_NAME_HIDE)
     reflow(this._element)
-    this._element.classList.add(ClassName.SHOWING)
+    this._element.classList.add(CLASS_NAME_SHOWING)
     if (this._config.animation) {
       const transitionDuration = getTransitionDurationFromElement(this._element)
 
@@ -128,22 +122,22 @@ class Toast {
   }
 
   hide() {
-    if (!this._element.classList.contains(ClassName.SHOW)) {
+    if (!this._element.classList.contains(CLASS_NAME_SHOW)) {
       return
     }
 
-    const hideEvent = EventHandler.trigger(this._element, Event.HIDE)
+    const hideEvent = EventHandler.trigger(this._element, EVENT_HIDE)
 
     if (hideEvent.defaultPrevented) {
       return
     }
 
     const complete = () => {
-      this._element.classList.add(ClassName.HIDE)
-      EventHandler.trigger(this._element, Event.HIDDEN)
+      this._element.classList.add(CLASS_NAME_HIDE)
+      EventHandler.trigger(this._element, EVENT_HIDDEN)
     }
 
-    this._element.classList.remove(ClassName.SHOW)
+    this._element.classList.remove(CLASS_NAME_SHOW)
     if (this._config.animation) {
       const transitionDuration = getTransitionDurationFromElement(this._element)
 
@@ -158,11 +152,11 @@ class Toast {
     clearTimeout(this._timeout)
     this._timeout = null
 
-    if (this._element.classList.contains(ClassName.SHOW)) {
-      this._element.classList.remove(ClassName.SHOW)
+    if (this._element.classList.contains(CLASS_NAME_SHOW)) {
+      this._element.classList.remove(CLASS_NAME_SHOW)
     }
 
-    EventHandler.off(this._element, Event.CLICK_DISMISS)
+    EventHandler.off(this._element, EVENT_CLICK_DISMISS)
     Data.removeData(this._element, DATA_KEY)
 
     this._element = null
@@ -190,8 +184,8 @@ class Toast {
   _setListeners() {
     EventHandler.on(
       this._element,
-      Event.CLICK_DISMISS,
-      Selector.DATA_DISMISS,
+      EVENT_CLICK_DISMISS,
+      SELECTOR_DATA_DISMISS,
       () => this.hide()
     )
   }
diff --git a/js/src/tooltip.js b/js/src/tooltip.js
index 9b2ae6f61e..b723b1ba83 100644
--- a/js/src/tooltip.js
+++ b/js/src/tooltip.js
@@ -89,11 +89,6 @@ const Default = {
   popperConfig: null
 }
 
-const HoverState = {
-  SHOW: 'show',
-  OUT: 'out'
-}
-
 const Event = {
   HIDE: `hide${EVENT_KEY}`,
   HIDDEN: `hidden${EVENT_KEY}`,
@@ -107,22 +102,19 @@ const Event = {
   MOUSELEAVE: `mouseleave${EVENT_KEY}`
 }
 
-const ClassName = {
-  FADE: 'fade',
-  MODAL: 'modal',
-  SHOW: 'show'
-}
+const CLASS_NAME_FADE = 'fade'
+const CLASS_NAME_MODAL = 'modal'
+const CLASS_NAME_SHOW = 'show'
 
-const Selector = {
-  TOOLTIP_INNER: '.tooltip-inner'
-}
+const HOVER_STATE_SHOW = 'show'
+const HOVER_STATE_OUT = 'out'
 
-const Trigger = {
-  HOVER: 'hover',
-  FOCUS: 'focus',
-  CLICK: 'click',
-  MANUAL: 'manual'
-}
+const SELECTOR_TOOLTIP_INNER = '.tooltip-inner'
+
+const TRIGGER_HOVER = 'hover'
+const TRIGGER_FOCUS = 'focus'
+const TRIGGER_CLICK = 'click'
+const TRIGGER_MANUAL = 'manual'
 
 /**
  * ------------------------------------------------------------------------
@@ -221,7 +213,7 @@ class Tooltip {
         context._leave(null, context)
       }
     } else {
-      if (this.getTipElement().classList.contains(ClassName.SHOW)) {
+      if (this.getTipElement().classList.contains(CLASS_NAME_SHOW)) {
         this._leave(null, this)
         return
       }
@@ -236,7 +228,7 @@ class Tooltip {
     Data.removeData(this.element, this.constructor.DATA_KEY)
 
     EventHandler.off(this.element, this.constructor.EVENT_KEY)
-    EventHandler.off(SelectorEngine.closest(this.element, `.${ClassName.MODAL}`), 'hide.bs.modal', this._hideModalHandler)
+    EventHandler.off(SelectorEngine.closest(this.element, `.${CLASS_NAME_MODAL}`), 'hide.bs.modal', this._hideModalHandler)
 
     if (this.tip) {
       this.tip.parentNode.removeChild(this.tip)
@@ -281,7 +273,7 @@ class Tooltip {
       this.setContent()
 
       if (this.config.animation) {
-        tip.classList.add(ClassName.FADE)
+        tip.classList.add(CLASS_NAME_FADE)
       }
 
       const placement = typeof this.config.placement === 'function' ?
@@ -302,7 +294,7 @@ class Tooltip {
 
       this._popper = new Popper(this.element, tip, this._getPopperConfig(attachment))
 
-      tip.classList.add(ClassName.SHOW)
+      tip.classList.add(CLASS_NAME_SHOW)
 
       // If this is a touch-enabled device we add extra
       // empty mouseover listeners to the body's immediate children;
@@ -324,12 +316,12 @@ class Tooltip {
 
         EventHandler.trigger(this.element, this.constructor.Event.SHOWN)
 
-        if (prevHoverState === HoverState.OUT) {
+        if (prevHoverState === HOVER_STATE_OUT) {
           this._leave(null, this)
         }
       }
 
-      if (this.tip.classList.contains(ClassName.FADE)) {
+      if (this.tip.classList.contains(CLASS_NAME_FADE)) {
         const transitionDuration = getTransitionDurationFromElement(this.tip)
         EventHandler.one(this.tip, TRANSITION_END, complete)
         emulateTransitionEnd(this.tip, transitionDuration)
@@ -342,7 +334,7 @@ class Tooltip {
   hide() {
     const tip = this.getTipElement()
     const complete = () => {
-      if (this._hoverState !== HoverState.SHOW && tip.parentNode) {
+      if (this._hoverState !== HOVER_STATE_SHOW && tip.parentNode) {
         tip.parentNode.removeChild(tip)
       }
 
@@ -357,7 +349,7 @@ class Tooltip {
       return
     }
 
-    tip.classList.remove(ClassName.SHOW)
+    tip.classList.remove(CLASS_NAME_SHOW)
 
     // If this is a touch-enabled device we remove the extra
     // empty mouseover listeners we added for iOS support
@@ -366,11 +358,11 @@ class Tooltip {
         .forEach(element => EventHandler.off(element, 'mouseover', noop))
     }
 
-    this._activeTrigger[Trigger.CLICK] = false
-    this._activeTrigger[Trigger.FOCUS] = false
-    this._activeTrigger[Trigger.HOVER] = false
+    this._activeTrigger[TRIGGER_CLICK] = false
+    this._activeTrigger[TRIGGER_FOCUS] = false
+    this._activeTrigger[TRIGGER_HOVER] = false
 
-    if (this.tip.classList.contains(ClassName.FADE)) {
+    if (this.tip.classList.contains(CLASS_NAME_FADE)) {
       const transitionDuration = getTransitionDurationFromElement(tip)
 
       EventHandler.one(tip, TRANSITION_END, complete)
@@ -408,9 +400,9 @@ class Tooltip {
 
   setContent() {
     const tip = this.getTipElement()
-    this.setElementContent(SelectorEngine.findOne(Selector.TOOLTIP_INNER, tip), this.getTitle())
-    tip.classList.remove(ClassName.FADE)
-    tip.classList.remove(ClassName.SHOW)
+    this.setElementContent(SelectorEngine.findOne(SELECTOR_TOOLTIP_INNER, tip), this.getTitle())
+    tip.classList.remove(CLASS_NAME_FADE)
+    tip.classList.remove(CLASS_NAME_SHOW)
   }
 
   setElementContent(element, content) {
@@ -539,11 +531,11 @@ class Tooltip {
           this.config.selector,
           event => this.toggle(event)
         )
-      } else if (trigger !== Trigger.MANUAL) {
-        const eventIn = trigger === Trigger.HOVER ?
+      } else if (trigger !== TRIGGER_MANUAL) {
+        const eventIn = trigger === TRIGGER_HOVER ?
           this.constructor.Event.MOUSEENTER :
           this.constructor.Event.FOCUSIN
-        const eventOut = trigger === Trigger.HOVER ?
+        const eventOut = trigger === TRIGGER_HOVER ?
           this.constructor.Event.MOUSELEAVE :
           this.constructor.Event.FOCUSOUT
 
@@ -566,7 +558,7 @@ class Tooltip {
       }
     }
 
-    EventHandler.on(SelectorEngine.closest(this.element, `.${ClassName.MODAL}`),
+    EventHandler.on(SelectorEngine.closest(this.element, `.${CLASS_NAME_MODAL}`),
       'hide.bs.modal',
       this._hideModalHandler
     )
@@ -609,19 +601,19 @@ class Tooltip {
 
     if (event) {
       context._activeTrigger[
-        event.type === 'focusin' ? Trigger.FOCUS : Trigger.HOVER
+        event.type === 'focusin' ? TRIGGER_FOCUS : TRIGGER_HOVER
       ] = true
     }
 
-    if (context.getTipElement().classList.contains(ClassName.SHOW) ||
-        context._hoverState === HoverState.SHOW) {
-      context._hoverState = HoverState.SHOW
+    if (context.getTipElement().classList.contains(CLASS_NAME_SHOW) ||
+        context._hoverState === HOVER_STATE_SHOW) {
+      context._hoverState = HOVER_STATE_SHOW
       return
     }
 
     clearTimeout(context._timeout)
 
-    context._hoverState = HoverState.SHOW
+    context._hoverState = HOVER_STATE_SHOW
 
     if (!context.config.delay || !context.config.delay.show) {
       context.show()
@@ -629,7 +621,7 @@ class Tooltip {
     }
 
     context._timeout = setTimeout(() => {
-      if (context._hoverState === HoverState.SHOW) {
+      if (context._hoverState === HOVER_STATE_SHOW) {
         context.show()
       }
     }, context.config.delay.show)
@@ -649,7 +641,7 @@ class Tooltip {
 
     if (event) {
       context._activeTrigger[
-        event.type === 'focusout' ? Trigger.FOCUS : Trigger.HOVER
+        event.type === 'focusout' ? TRIGGER_FOCUS : TRIGGER_HOVER
       ] = false
     }
 
@@ -659,7 +651,7 @@ class Tooltip {
 
     clearTimeout(context._timeout)
 
-    context._hoverState = HoverState.OUT
+    context._hoverState = HOVER_STATE_OUT
 
     if (!context.config.delay || !context.config.delay.hide) {
       context.hide()
@@ -667,7 +659,7 @@ class Tooltip {
     }
 
     context._timeout = setTimeout(() => {
-      if (context._hoverState === HoverState.OUT) {
+      if (context._hoverState === HOVER_STATE_OUT) {
         context.hide()
       }
     }, context.config.delay.hide)
@@ -768,7 +760,7 @@ class Tooltip {
       return
     }
 
-    tip.classList.remove(ClassName.FADE)
+    tip.classList.remove(CLASS_NAME_FADE)
     this.config.animation = false
     this.hide()
     this.show()