1 files changed, 23 insertions, 5 deletions
diff --git a/js/src/modal.js b/js/src/modal.js
index 61a28dbf5..70bb68e42 100644
--- a/js/src/modal.js
+++ b/js/src/modal.js
@@ -87,6 +87,7 @@ const Modal = (($) => {
       this._isShown             = false
       this._isBodyOverflowing   = false
       this._ignoreBackdropClick = false
+      this._isTransitioning     = false
       this._originalBodyPadding = 0
       this._scrollbarWidth      = 0
     }
@@ -110,6 +111,14 @@ const Modal = (($) => {
     }
 
     show(relatedTarget) {
+      if (this._isTransitioning) {
+        throw new Error('Modal is transitioning')
+      }
+
+      if (Util.supportsTransitionEnd() &&
+        $(this._element).hasClass(ClassName.FADE)) {
+        this._isTransitioning = true
+      }
       const showEvent = $.Event(Event.SHOW, {
         relatedTarget
       })
@@ -152,8 +161,17 @@ const Modal = (($) => {
         event.preventDefault()
       }
 
-      const hideEvent = $.Event(Event.HIDE)
+      if (this._isTransitioning) {
+        throw new Error('Modal is transitioning')
+      }
 
+      const transition = Util.supportsTransitionEnd() &&
+        $(this._element).hasClass(ClassName.FADE)
+      if (transition) {
+        this._isTransitioning = true
+      }
+
+      const hideEvent = $.Event(Event.HIDE)
       $(this._element).trigger(hideEvent)
 
       if (!this._isShown || hideEvent.isDefaultPrevented()) {
@@ -172,9 +190,7 @@ const Modal = (($) => {
       $(this._element).off(Event.CLICK_DISMISS)
       $(this._dialog).off(Event.MOUSEDOWN_DISMISS)
 
-      if (Util.supportsTransitionEnd() &&
-         $(this._element).hasClass(ClassName.FADE)) {
-
+      if (transition) {
         $(this._element)
           .one(Util.TRANSITION_END, (event) => this._hideModal(event))
           .emulateTransitionEnd(TRANSITION_DURATION)
@@ -240,6 +256,7 @@ const Modal = (($) => {
         if (this._config.focus) {
           this._element.focus()
         }
+        this._isTransitioning = false
         $(this._element).trigger(shownEvent)
       }
 
@@ -287,7 +304,8 @@ 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)
         this._resetAdjustments()