1 files changed, 21 insertions, 4 deletions

diff --git a/js/dist/modal.js b/js/dist/modal.js
index 68880ad58..d9797567c 100644
--- a/js/dist/modal.js
+++ b/js/dist/modal.js
@@ -89,6 +89,7 @@ var Modal = function ($) {
       this._isShown = false;
       this._isBodyOverflowing = false;
       this._ignoreBackdropClick = false;
+      this._isTransitioning = false;
       this._originalBodyPadding = 0;
       this._scrollbarWidth = 0;
     }
@@ -104,6 +105,13 @@ var Modal = function ($) {
     Modal.prototype.show = function show(relatedTarget) {
       var _this = this;
 
+      if (this._isTransitioning) {
+        throw new Error('Modal is transitioning');
+      }
+
+      if (Util.supportsTransitionEnd() && $(this._element).hasClass(ClassName.FADE)) {
+        this._isTransitioning = true;
+      }
       var showEvent = $.Event(Event.SHOW, {
         relatedTarget: relatedTarget
       });
@@ -148,8 +156,16 @@ var Modal = function ($) {
         event.preventDefault();
       }
 
-      var hideEvent = $.Event(Event.HIDE);
+      if (this._isTransitioning) {
+        throw new Error('Modal is transitioning');
+      }
+
+      var transition = Util.supportsTransitionEnd() && $(this._element).hasClass(ClassName.FADE);
+      if (transition) {
+        this._isTransitioning = true;
+      }
 
+      var hideEvent = $.Event(Event.HIDE);
       $(this._element).trigger(hideEvent);
 
       if (!this._isShown || hideEvent.isDefaultPrevented()) {
@@ -168,8 +184,7 @@ var Modal = function ($) {
       $(this._element).off(Event.CLICK_DISMISS);
       $(this._dialog).off(Event.MOUSEDOWN_DISMISS);
 
-      if (Util.supportsTransitionEnd() && $(this._element).hasClass(ClassName.FADE)) {
-
+      if (transition) {
         $(this._element).one(Util.TRANSITION_END, function (event) {
           return _this2._hideModal(event);
         }).emulateTransitionEnd(TRANSITION_DURATION);
@@ -234,6 +249,7 @@ var Modal = function ($) {
         if (_this3._config.focus) {
           _this3._element.focus();
         }
+        _this3._isTransitioning = false;
         $(_this3._element).trigger(shownEvent);
       };
 
@@ -285,7 +301,8 @@ var Modal = function ($) {
       var _this7 = this;
 
       this._element.style.display = 'none';
-      this._element.setAttribute('aria-hidden', true);
+      this._element.setAttribute('aria-hidden', 'true');
+      this._isTransitioning = false;
       this._showBackdrop(function () {
         $(document.body).removeClass(ClassName.OPEN);
         _this7._resetAdjustments();