Fix carousel transition duration

js/src/carousel.js

@@ -18,16 +18,16 @@ const Carousel = (($) => {
    * ------------------------------------------------------------------------
    */
 
-  const NAME                   = 'carousel'
-  const VERSION                = '4.0.0-beta.3'
-  const DATA_KEY               = 'bs.carousel'
-  const EVENT_KEY              = `.${DATA_KEY}`
-  const DATA_API_KEY           = '.data-api'
-  const JQUERY_NO_CONFLICT     = $.fn[NAME]
-  const TRANSITION_DURATION    = 600
-  const ARROW_LEFT_KEYCODE     = 37 // KeyboardEvent.which value for left arrow key
-  const ARROW_RIGHT_KEYCODE    = 39 // KeyboardEvent.which value for right arrow key
-  const TOUCHEVENT_COMPAT_WAIT = 500 // Time for mouse compat events to fire after touch
+  const NAME                    = 'carousel'
+  const VERSION                 = '4.0.0-beta.3'
+  const DATA_KEY                = 'bs.carousel'
+  const EVENT_KEY               = `.${DATA_KEY}`
+  const DATA_API_KEY            = '.data-api'
+  const JQUERY_NO_CONFLICT      = $.fn[NAME]
+  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 MILLISECONDS_MULTIPLIER = 1000
 
   const Default = {
     interval : 5000,
@@ -94,18 +94,20 @@ const Carousel = (($) => {
   class Carousel {
 
     constructor(element, config) {
-      this._items             = null
-      this._interval          = null
-      this._activeElement     = null
+      this._items              = null
+      this._interval           = null
+      this._activeElement      = null
 
-      this._isPaused          = false
-      this._isSliding         = false
+      this._isPaused           = false
+      this._isSliding          = false
 
-      this.touchTimeout       = null
+      this.touchTimeout        = null
 
-      this._config            = this._getConfig(config)
-      this._element           = $(element)[0]
-      this._indicatorsElement = $(this._element).find(Selector.INDICATORS)[0]
+      this._config             = this._getConfig(config)
+      this._element            = $(element)[0]
+      this._indicatorsElement  = $(this._element).find(Selector.INDICATORS)[0]
+
+      this._transitionDuration = this._getTransitionDuration()
 
       this._addEventListeners()
     }
@@ -231,6 +233,23 @@ const Carousel = (($) => {
       return config
     }
 
+    _getTransitionDuration() {
+      // Get transition-duration of first element in the carousel
+      let transitionDuration = $(this._element).find(Selector.ITEM).css('transition-duration')
+
+      // Return 0 carousel item is not found
+      if (!transitionDuration) {
+        return 0
+      }
+
+      // If multiple durations are defined, take the first
+      transitionDuration = transitionDuration.split(',')[0]
+
+      // Multiply by 1000 if transition-duration is defined in seconds
+      return transitionDuration.indexOf('ms') > -1 ?
+        parseFloat(transitionDuration) : parseFloat(transitionDuration) * MILLISECONDS_MULTIPLIER
+    }
+
     _addEventListeners() {
       if (this._config.keyboard) {
         $(this._element)
@@ -410,7 +429,7 @@ const Carousel = (($) => {
             setTimeout(() => $(this._element).trigger(slidEvent), 0)
 
           })
-          .emulateTransitionEnd(TRANSITION_DURATION)
+          .emulateTransitionEnd(this._transitionDuration)
 
       } else {
         $(activeElement).removeClass(ClassName.ACTIVE)

scss/_variables.scss

@@ -858,7 +858,8 @@ $carousel-control-icon-width:       20px !default;
 
 $carousel-control-prev-icon-bg:     str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='#{$carousel-control-color}' viewBox='0 0 8 8'%3E%3Cpath d='M5.25 0l-4 4 4 4 1.5-1.5-2.5-2.5 2.5-2.5-1.5-1.5z'/%3E%3C/svg%3E"), "#", "%23") !default;
 $carousel-control-next-icon-bg:     str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='#{$carousel-control-color}' viewBox='0 0 8 8'%3E%3Cpath d='M2.75 0l-1.5 1.5 2.5 2.5-2.5 2.5 1.5 1.5 4-4-4-4z'/%3E%3C/svg%3E"), "#", "%23") !default;
-
+// If multiple transitions are applied, make sure the transform transition is defined first
+// eg. transform 2s ease, opacity .5s ease-out
 $carousel-transition:               transform .6s ease !default;