Check for data-interval on the first slide of carousel (#31818)

* check for data-interval on the first slide of carousel

* add updateInterval method for elements of a carousel

* add test for carousel interval being set during cycle

* update activeElement as soon as slide has finished (before transition end)

* only updateInterval before using it

Co-authored-by: XhmikosR <xhmikosr@gmail.com>

js/src/carousel.js

@@ -181,6 +181,8 @@ class Carousel {
     }
 
     if (this._config && this._config.interval && !this._isPaused) {
+      this._updateInterval()
+
       this._interval = setInterval(
         (document.visibilityState ? this.nextWhenVisible : this.next).bind(this),
         this._config.interval
@@ -409,6 +411,23 @@ class Carousel {
     }
   }
 
+  _updateInterval() {
+    const element = this._activeElement || SelectorEngine.findOne(SELECTOR_ACTIVE_ITEM, this._element)
+
+    if (!element) {
+      return
+    }
+
+    const elementInterval = parseInt(element.getAttribute('data-interval'), 10)
+
+    if (elementInterval) {
+      this._config.defaultInterval = this._config.defaultInterval || this._config.interval
+      this._config.interval = elementInterval
+    } else {
+      this._config.interval = this._config.defaultInterval || this._config.interval
+    }
+  }
+
   _slide(direction, element) {
     const activeElement = SelectorEngine.findOne(SELECTOR_ACTIVE_ITEM, this._element)
     const activeElementIndex = this._getItemIndex(activeElement)
@@ -454,6 +473,7 @@ class Carousel {
     }
 
     this._setActiveIndicatorElement(nextElement)
+    this._activeElement = nextElement
 
     if (this._element.classList.contains(CLASS_NAME_SLIDE)) {
       nextElement.classList.add(orderClassName)
@@ -463,14 +483,6 @@ class Carousel {
       activeElement.classList.add(directionalClassName)
       nextElement.classList.add(directionalClassName)
 
-      const nextElementInterval = parseInt(nextElement.getAttribute('data-interval'), 10)
-      if (nextElementInterval) {
-        this._config.defaultInterval = this._config.defaultInterval || this._config.interval
-        this._config.interval = nextElementInterval
-      } else {
-        this._config.interval = this._config.defaultInterval || this._config.interval
-      }
-
       const transitionDuration = getTransitionDurationFromElement(activeElement)
 
       EventHandler.one(activeElement, TRANSITION_END, () => {

js/tests/unit/carousel.spec.js

@@ -636,27 +636,24 @@ describe('Carousel', () => {
       carousel.next()
     })
 
-    it('should get interval from data attribute in individual item', () => {
+    it('should update the active element to the next item before sliding', () => {
       fixtureEl.innerHTML = [
         '<div id="myCarousel" class="carousel slide">',
         '  <div class="carousel-inner">',
         '    <div class="carousel-item active">item 1</div>',
-        '    <div class="carousel-item" data-interval="7">item 2</div>',
+        '    <div id="secondItem" class="carousel-item">item 2</div>',
         '    <div class="carousel-item">item 3</div>',
         '  </div>',
         '</div>'
       ].join('')
 
       const carouselEl = fixtureEl.querySelector('#myCarousel')
-      const carousel = new Carousel(carouselEl, {
+      const secondItemEl = fixtureEl.querySelector('#secondItem')
-        interval: 1814
+      const carousel = new Carousel(carouselEl)
-      })
-
-      expect(carousel._config.interval).toEqual(1814)
 
       carousel.next()
 
-      expect(carousel._config.interval).toEqual(7)
+      expect(carousel._activeElement).toEqual(secondItemEl)
     })
 
     it('should update indicators if present', done => {
@@ -876,6 +873,35 @@ describe('Carousel', () => {
       expect(window.setInterval).toHaveBeenCalled()
       expect(window.clearInterval).toHaveBeenCalled()
     })
+
+    it('should get interval from data attribute on the active item element', () => {
+      fixtureEl.innerHTML = [
+        '<div id="myCarousel" class="carousel slide">',
+        '  <div class="carousel-inner">',
+        '    <div class="carousel-item active" data-interval="7">item 1</div>',
+        '    <div id="secondItem" class="carousel-item" data-interval="9385">item 2</div>',
+        '    <div class="carousel-item">item 3</div>',
+        '  </div>',
+        '</div>'
+      ].join('')
+
+      const carouselEl = fixtureEl.querySelector('#myCarousel')
+      const secondItemEl = fixtureEl.querySelector('#secondItem')
+      const carousel = new Carousel(carouselEl, {
+        interval: 1814
+      })
+
+      expect(carousel._config.interval).toEqual(1814)
+
+      carousel.cycle()
+
+      expect(carousel._config.interval).toEqual(7)
+
+      carousel._activeElement = secondItemEl
+      carousel.cycle()
+
+      expect(carousel._config.interval).toEqual(9385)
+    })
   })
 
   describe('to', () => {